The splitting of an ancestral species into daughter species that coexist in time (King, Dictionary of Genetics, 6th ed). Causal factors may include geographic isolation, HABITAT geometry, migration, REPRODUCTIVE ISOLATION, random GENETIC DRIFT and MUTATION.
Mechanisms that prevent different populations from exchanging genes (GENE FLOW), resulting in or maintaining GENETIC SPECIATION. It can either prevent mating to take place or ensure that any offspring produced is either inviable or sterile, thereby preventing further REPRODUCTION.
The change in gene frequency in a population due to migration of gametes or individuals (ANIMAL MIGRATION) across population barriers. In contrast, in GENETIC DRIFT the cause of gene frequency changes are not a result of population or gamete movement.
The genetic process of crossbreeding between genetically dissimilar parents to produce a hybrid.
The relationships of groups of organisms as reflected by their genetic makeup.
The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.
The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.
The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.
In evolutionary theory, overlapping geographic distribution of diverging species. In sympatric GENETIC SPECIATION, genetic diversion occurs without geographic separation.
The science dealing with the earth and its life, especially the description of land, sea, and air and the distribution of plant and animal life, including humanity and human industries with reference to the mutual relations of these elements. (From Webster, 3d ed)
Common name for perch-like fish of the family Cichlidae, belonging to the suborder Labroidei, order PERCIFORMES.
Genotypic differences observed among individuals in a population.
Changes in biological features that help an organism cope with its ENVIRONMENT. These changes include physiological (ADAPTATION, PHYSIOLOGICAL), phenotypic and genetic changes.
The total process by which organisms produce offspring. (Stedman, 25th ed)
Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.
The discipline studying genetic composition of populations and effects of factors such as GENETIC SELECTION, population size, MUTATION, migration, and GENETIC DRIFT on the frequencies of various GENOTYPES and PHENOTYPES using a variety of GENETIC TECHNIQUES.
Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.
A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)
Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.
A field of study concerned with the principles and processes governing the geographic distributions of genealogical lineages, especially those within and among closely related species. (Avise, J.C., Phylogeography: The History and Formation of Species. Harvard University Press, 2000)
Slender-bodies diurnal insects having large, broad wings often strikingly colored and patterned.
Sexual activities of animals.
The variety of all native living organisms and their various forms and interrelationships.
Analysis of the energy absorbed across a spectrum of x-ray energies/wavelengths to determine the chemical structure and electronic states of the absorbing medium.
The branch of science concerned with the interrelationship of organisms and their ENVIRONMENT, especially as manifested by natural cycles and rhythms, community development and structure, interactions between different kinds of organisms, geographic distributions, and population alterations. (Webster's, 3d ed)
A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.
The detection of RESTRICTION FRAGMENT LENGTH POLYMORPHISMS by selective PCR amplification of restriction fragments derived from genomic DNA followed by electrophoretic analysis of the amplified restriction fragments.
The selection or choice of sexual partner in animals. Often this reproductive preference is based on traits in the potential mate, such as coloration, size, or behavioral boldness. If the chosen ones are genetically different from the rejected ones, then NATURAL SELECTION is occurring.
The ceasing of existence of a species or taxonomic groups of organisms.
Members of the group of vascular plants which bear flowers. They are differentiated from GYMNOSPERMS by their production of seeds within a closed chamber (OVARY, PLANT). The Angiosperms division is composed of two classes, the monocotyledons (Liliopsida) and dicotyledons (Magnoliopsida). Angiosperms represent approximately 80% of all known living plants.
A theorem in probability theory named for Thomas Bayes (1702-1761). In epidemiology, it is used to obtain the probability of disease in a group of people with some characteristic on the basis of the overall rate of that disease and of the likelihood of that characteristic in healthy and diseased individuals. The most familiar application is in clinical decision analysis where it is used for estimating the probability of a particular diagnosis given the appearance of some symptoms or test result.
An arsenical that has been used as a dermatologic agent and as an herbicide.
The chromosomal constitution of a cell containing multiples of the normal number of CHROMOSOMES; includes triploidy (symbol: 3N), tetraploidy (symbol: 4N), etc.
A widely distributed order of perching BIRDS, including more than half of all bird species.
The inanimate matter of Earth, the structures and properties of this matter, and the processes that affect it.
The fluctuation of the ALLELE FREQUENCY from one generation to the next.
A shiny gray element with atomic symbol As, atomic number 33, and atomic weight 75. It occurs throughout the universe, mostly in the form of metallic arsenides. Most forms are toxic. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), arsenic and certain arsenic compounds have been listed as known carcinogens. (From Merck Index, 11th ed)
Functions constructed from a statistical model and a set of observed data which give the probability of that data for various values of the unknown model parameters. Those parameter values that maximize the probability are the maximum likelihood estimates of the parameters.
Water containing no significant amounts of salts, such as water from RIVERS and LAKES.
Coloration or discoloration of a part by a pigment.
A large family of fruit flies in the order DIPTERA, comprising over 4,500 species in about 100 genera. They have patterned wings and brightly colored bodies and are found predominantly in the tropical latitudes.
The longterm manifestations of WEATHER. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
The family Gryllidae consists of the common house cricket, Acheta domesticus, which is used in neurological and physiological studies. Other genera include Gryllotalpa (mole cricket); Gryllus (field cricket); and Oecanthus (tree cricket).
Remains, impressions, or traces of animals or plants of past geological times which have been preserved in the earth's crust.
Cytochromes of the b group that have alpha-band absorption of 563-564 nm. They occur as subunits in MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX III.
Inorganic or organic compounds that contain arsenic.
The science of the earth and other celestial bodies and their history as recorded in the rocks. It includes the study of geologic processes of an area such as rock formations, weathering and erosion, and sedimentation. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A variety of simple repeat sequences that are distributed throughout the GENOME. They are characterized by a short repeat unit of 2-8 basepairs that is repeated up to 100 times. They are also known as short tandem repeats (STRs).
The custard-apple plant family of the order Magnoliales, subclass Magnoliidae, class Magnoliopsida. Some members provide large pulpy fruits and commercial timber. Leaves and wood are often fragrant. Leaves are simple, with smooth margins, and alternately arranged in two rows along the stems.
The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population.
In some animals, the jaws together with their horny covering. The beak usually refers to the bill of birds in which the whole varies greatly in form according of the food and habits of the bird. While the beak refers most commonly to birds, the anatomical counterpart is found also in the turtle, squid, and octopus. (From Webster, 3d ed & Storer, et al., General Zoology, 6th ed, p491, 755)
A species of toxic plants of the Compositae. The poisonous compounds are alkaloids which cause cattle diseases, neoplasms, and liver damage and are used to produce cancers in experimental animals.
Periodic movements of animals in response to seasonal changes or reproductive instinct. Hormonal changes are the trigger in at least some animals. Most migrations are made for reasons of climatic change, feeding, or breeding.
Deoxyribonucleic acid that makes up the genetic material of CHLOROPLASTS.
The external elements and conditions which surround, influence, and affect the life and development of an organism or population.
Inland bodies of still or slowly moving FRESH WATER or salt water, larger than a pond, and supplied by RIVERS and streams.
A great expanse of continuous bodies of salt water which together cover more than 70 percent of the earth's surface. Seas may be partially or entirely enclosed by land, and are smaller than the five oceans (Atlantic, Pacific, Indian, Arctic, and Antarctic).
A class in the phylum MOLLUSCA comprised of SNAILS and slugs. The former have coiled external shells and the latter usually lack shells.
This single species of Gorilla, which is a member of the HOMINIDAE family, is the largest and most powerful of the PRIMATES. It is distributed in isolated scattered populations throughout forests of equatorial Africa.
Deoxyribonucleic acid that makes up the genetic material of plants.
Spectrophotometric techniques by which the absorption or emmision spectra of radiation from atoms are produced and analyzed.
The geographical area of Africa comprising BURUNDI; DJIBOUTI; ETHIOPIA; KENYA; RWANDA; SOMALIA; SUDAN; TANZANIA; and UGANDA.
Organic matter in a state of advanced decay, after passing through the stages of COMPOST and PEAT and before becoming lignite (COAL). It is composed of a heterogenous mixture of compounds including phenolic radicals and acids that polymerize and are not easily separated nor analyzed. (E.A. Ghabbour & G. Davies, eds. Humic Substances, 2001).
A plant genus of the family CRUCIFERAE.
A plant genus of the family ACERACEAE, best known for trees with palmately lobed leaves.
A genus of orangutans in the family HOMINIDAE, comprising two species. Among the PRIMATES, the orangutan is second in size only to the gorilla (GORILLA GORILLA).
Processes occurring in various organisms by which new genes are copied. Gene duplication may result in a MULTIGENE FAMILY; supergenes or PSEUDOGENES.
Geographic variety, population, or race, within a species, that is genetically adapted to a particular habitat. An ecotype typically exhibits phenotypic differences but is capable of interbreeding with other ecotypes.
The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.
Structures within the CELL NUCLEUS of insect cells containing DNA.
Group of fish under the superorder Acanthopterygii, separate from the PERCIFORMES, which includes swamp eels, mullets, sticklebacks, seahorses, spiny eels, rainbowfishes, and KILLIFISHES. The name is derived from the six taxa which comprise the group. (From, 8/4/2000)
Warm-blooded VERTEBRATES possessing FEATHERS and belonging to the class Aves.
The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)

Reconstructing the origin of Helianthus deserticola: survival and selection on the desert floor. (1/1185)

The diploid hybrid species Helianthus deserticola inhabits the desert floor, an extreme environment relative to its parental species Helianthus annuus and Helianthus petiolaris. Adaptation to the desert floor may have occurred via selection acting on transgressive, or extreme, traits in early hybrids between the parental species. We explored this possibility through a field experiment in the hybrid species' native habitat using H. deserticola, H. annuus, H. petiolaris, and two populations of early-generation (BC(2)) hybrids between the parental species, which served as proxies for the ancestral genotype of the ancient hybrid species. Character expression was evaluated for each genotypic class. Helianthus deserticola was negatively transgressive for stem diameter, leaf area, and flowering date, and the latter two traits are likely to be advantageous in a desert environment. The BC(2) hybrids contained a range of variation that overlapped these transgressive trait means, and an analysis of phenotypic selection revealed that some of the selective pressures on leaf size and flowering date, but not stem diameter, would move the BC(2) population toward the H. deserticola phenotype. Thus, H. deserticola may have originated from habitat-mediated directional selection acting on hybrids between H. annuus and H. petiolaris in a desert environment.  (+info)

On the dependence of speciation rates on species abundance and characteristic population size. (2/1185)

The question of the potential importance for speciation of large/small population sizes remains open. We compare speciation rates in twelve major taxonomic groups that differ by twenty orders of magnitude in characteristic species abundance (global population number). It is observed that the twenty orders of magnitude's difference in species abundances scales to less than two orders of magnitude's difference in speciation rates. As far as species abundance largely determines the rate of generation of intraspecific endogenous genetic variation, the result obtained suggests that the latter rate is not a limiting factor for speciation. Furthermore, the observed approximate constancy of speciation rates in different taxa cannot be accounted for by assuming a neutral or nearly neutral molecular clock in subdivided populations. Neutral fixation is only relevant in sufficiently small populations with 4N(e)v < 1, which appears an unrealistic condition for many taxa of the smaller organisms. Further research is clearly needed to reveal the mechanisms that could equate the evolutionary pace in taxa with dramatically different population sizes  (+info)

The ecological genetics of homoploid hybrid speciation. (3/1185)

Our understanding of homoploid hybrid speciation has advanced substantially since this mechanism of species formation was codified 50 years ago. Early theory and research focused almost exclusively on the importance of chromosomal rearrangements, but it later became evident that natural selection, specifically ecological selection, might play a major role as well. In light of this recent shift, we present an evaluation of ecology's role in homoploid hybrid speciation, with an emphasis on the genetics underlying ecological components of the speciation process. We briefly review new theoretical developments related to the ecology of homoploid hybrid speciation; propose a set of explicit, testable questions that must be answered to verify the role of ecological selection in homoploid hybrid speciation; discuss published work with reference to these questions; and also report new data supporting the importance of ecological selection in the origin of the homoploid hybrid sunflower species Helianthus deserticola. Overall, theory and empirical evidence gathered to date suggest that ecological selection is a major factor promoting homoploid hybrid speciation, with the strongest evidence coming from genetic studies.  (+info)

Assessing the origin of species in the genomic era. (4/1185)

Advances in genomics have rapidly accelerated research into the genetics of species differences, reproductive isolating barriers, and hybrid incompatibility. Recent genomic analyses in Drosophila species suggest that modified olfactory cues are involved in discrimination that is reinforced by natural selection.  (+info)

Contrasting patterns of polymorphism and divergence on the Z chromosome and autosomes in two Ficedula flycatcher species. (5/1185)

In geographic areas where pied and collared flycatchers (Ficedula hypoleuca and F. albicollis) breed in sympatry, hybridization occurs, leading to gene flow (introgression) between the two recently diverged species. Notably, while such introgression is observable at autosomal loci it is apparently absent at the Z chromosome, suggesting an important role for genes on the Z chromosome in creating reproductive isolation during speciation. To further understand the role of Z-linked loci in the formation of new species, we studied genetic variation of the two species from regions where they live in allopatry. We analyzed patterns of polymorphism and divergence in introns from 9 Z-linked and 23 autosomal genes in pied and collared flycatcher males. Average variation on the Z chromosome is greatly reduced compared to neutral expectations based on autosomal diversity in both species. We also observe significant heterogeneity between patterns of polymorphism and divergence at Z-linked loci and a relative absence of polymorphisms that are shared by the two species on the Z chromosome compared to the autosomes. We suggest that these observations may indicate the action of recurrent selective sweeps on the Z chromosome during the evolution of the two species, which may be caused by sexual selection acting on Z-linked genes. Alternatively, reduced variation on the Z chromosome could result from substantially higher levels of introgression at autosomal than at Z-linked loci or from a complex demographic history, such as a population bottleneck.  (+info)

Genetic mapping of species boundaries in Louisiana irises using IRRE retrotransposon display markers. (6/1185)

Genetic mapping studies provide insight into the pattern and extent of genetic incompatibilities affecting hybridization between closely related species. Genetic maps of two species of Louisiana Irises, Iris fulva and I. brevicaulis, were constructed from transposon-based molecular markers segregating in reciprocal backcross (BC1) interspecific hybrids and used to investigate genomic patterns of species barriers inhibiting introgression. Linkage mapping analyses indicated very little genetic incompatibility between I. fulva and I. brevicaulis in the form of map regions exhibiting transmission ratio distortion, and this was confirmed using a Bayesian multipoint mapping analysis. These results demonstrate the utility of transposon-based marker systems for genetic mapping studies of wild plant species and indicate that the genomes of I. fulva and I. brevicaulis are highly permeable to gene flow and introgression from one another via backcrossing.  (+info)

Signatures of reproductive isolation in patterns of single nucleotide diversity across inbred strains of mice. (7/1185)

Reproductive isolation is often caused by the disruption of genic interactions that evolve in geographically separate populations. Identifying the genomic regions and genes involved in these interactions, known as "Dobzhansky-Muller incompatibilities," can be challenging but is facilitated by the wealth of genetic markers now available in model systems. In recent years, the complete genome sequence and thousands of single nucleotide polymorphisms (SNPs) from laboratory mice, which are largely genetic hybrids between Mus musculus and M. domesticus, have become available. Here, we use these resources to locate genomic regions that may underlie reproductive isolation between these two species. Using genotypes from 332 SNPs that differ between wild-derived strains of M. musculus and M. domesticus, we identified several physically unlinked SNP pairs that show exceptional gametic disequilibrium across the lab strains. Conspecific alleles were associated in a disproportionate number of these cases, consistent with the action of natural selection against hybrid gene combinations. As predicted by the Dobzhansky-Muller model, this bias was differentially attributable to locus pairs for which one hybrid genotype was missing. We assembled a list of potential Dobzhansky-Muller incompatibilities from locus pairs that showed extreme associations (only three gametic types) among conspecific alleles. Two SNPs in this list map near known hybrid sterility loci on chromosome 17 and the X chromosome, allowing us to nominate partners for disrupted interactions involving these genomic regions for the first time. Together, these results indicate that patterns produced by speciation between M. musculus and M. domesticus are visible in the genomes of lab strains of mice, underscoring the potential of these genetic model organisms for addressing general questions in evolutionary biology.  (+info)

A test of founder effect speciation using multiple loci in the auklets (Aethia spp.). (8/1185)

Whether speciation results more frequently from the genetic consequences of founder events or from gradual genetic divergence of large populations is a matter of debate. In this study, multiple analyses were applied to data from three loci (cytochrome b, alpha-enolase intron VIII, and MHC class II B) to test for founder effects associated with speciation in Aethia (Aves: Alcidae), a genus of seabirds thought to have undergone a rapid founder-induced radiation. Effective population sizes (N(e)) were derived from estimators of based on allelic diversity and the coalescent and from data on trans-species polymorphism. Results indicated that N(e) has been on the order of 10(5)-10(6) individuals throughout the evolutionary histories of least and crested auklets (A. pusilla and A. cristatella, respectively) and that N(e) of the ancestral species was at least 16,000 individuals. Computer simulations of MHC evolution indicated that a single-generation bottleneck at speciation could not have involved <85 individuals for each species. More moderate simulation scenarios indicated that population size could not have dropped below 2000 individuals at the time of species founding. Demographic history appears to have been stable for the auklets throughout the past several million years, and a founder effect associated with their speciation is unlikely.  (+info)

It is not yet clear under what conditions empirical studies can reliably detect progress toward ecological speciation through the analysis of allelic variation at neutral loci. We use a simulation approach to investigate the range of parameter space under which such detection is, and is not, likely. We specifically test for the conditions under which divergent natural selection can cause a generalized barrier to gene flow that is present across the genome. Our individual-based numerical simulations focus on how population divergence at neutral loci varies in relation to recombination rate with a selected locus, divergent selection on that locus, migration rate and population size. We specifically test whether genetic differences at neutral markers are greater between populations in different environments than between populations in similar environments. We find that this expected signature of ecological speciation can be detected under part of the parameter space, most consistently when ...
Evidence for ecological speciation has accumulated from top-down studies of adaptation and reproductive isolation [reviewed in (2, 8, 9)]. We now know of many real species that have, at least in part, evolved by divergent natural selection between environments. The connections between selection on ordinary phenotypic traits and reproductive isolation are often strong and straightforward. It follows that much of the genetic basis of reproductive isolation should involve ordinary genes that underlie differences in phenotypic traits. But we still know little about the genetics of ecological speciation.. One line of evidence comes from tests of parallel speciation, whereby greater reproductive isolation repeatedly evolves between independent populations adapting to contrasting environments than between independent populations adapting to similar environments (20, 23). A major challenge in applying the test to natural populations is to eliminate the possibility that each ecotype has originated just ...
Ecological speciation can sometimes rapidly generate reproductively isolated populations coexisting in sympatry, but the origin of genetic variation permitting this is rarely known. We previously explored the genomics of very recent ecological speciation into lake and stream ecotypes in stickleback from Lake Constance. Here, we reconstruct the origin of alleles underlying ecological speciation by combining demographic modelling on genome-wide single nucleotide polymorphisms, phenotypic data and mitochondrial sequence data in the wider European biogeographical context. We find that parallel differentiation between lake and stream ecotypes across replicate lake-stream ecotones resulted from recent secondary contact and admixture between old East and West European lineages. Unexpectedly, West European alleles that introgressed across the hybrid zone at the western end of the lake, were recruited to genomic islands of differentiation between ecotypes at the eastern end of the lake. Our results highlight an
We are meeting this semester in the Biopharm 3rd Floor Fishbowl Mondays and Tuesdays 2-3pm. Please sign up for two dates on the schedule below. A list of topic ideas follows but you can choose anything related to speciation and hybridization. Subtopic Ideas: SPECIATION 1) What did Darwin say about speciation and hybridization? (First week) 2) When does a species become a species? How can the earliest stages of speciation be recognized? 3) How much genetic divergence should we expect within species? Are large genetic divergences within species due to polymorphisms/large population sizes, or artifacts, or are they simply due to our failure to recognize cryptic species? 4) Are there speciation genes? What are some examples? Are speciation genes restricted to a certain type of mutation or class of genes? HYBRIDIZATION: It has been estimated that at least 25% of plant species and 10% animal species hybridize* 1) How much gene flow occurs across species boundaries and what are the consequences for ...
We are meeting this semester in the Biopharm 3rd Floor Fishbowl Mondays and Tuesdays 2-3pm. Please sign up for two dates on the schedule below. A list of topic ideas follows but you can choose anything related to speciation and hybridization. Subtopic Ideas: SPECIATION 1) What did Darwin say about speciation and hybridization? (First week) 2) When does a species become a species? How can the earliest stages of speciation be recognized? 3) How much genetic divergence should we expect within species? Are large genetic divergences within species due to polymorphisms/large population sizes, or artifacts, or are they simply due to our failure to recognize cryptic species? 4) Are there speciation genes? What are some examples? Are speciation genes restricted to a certain type of mutation or class of genes? HYBRIDIZATION: It has been estimated that at least 25% of plant species and 10% animal species hybridize* 1) How much gene flow occurs across species boundaries and what are the consequences for ...
Explain the difference between the morphological species concept and the biological species concept.. With the morphological species concept, individuals are grouped into species by appearance and professional judgment. Those individuals that appear similar to one another are considered one species. This concept was the origin of taxonomy. Criticisms of this method are that it is arbitrary and that it may not be able to discriminate, for example, when one species mimics another. The biological species concept defines a species as a group of actually or potentially interbreeding individuals who are reproductively isolated from other groups. Individuals must be able to produce successful fertile offspring. Shortcomings of this concept are that it cannot be used with fossils or spatially disconnected populations.. Potential Question ...
Sympatric speciation, i.e. the evolutionary split of one species into two in the same environment, has been a highly troublesome concept. It has been a questioned if it is actually possible. Even though there have been a number of reported results both in the wild and from controlled experiments in laboratories, those findings are both hard to get and hard to analyze, or even repeat. In the current study we propose a mathematical model which addresses the question of sympatric speciation and the evolution of reinforcement. Our aim has been to capture some of the essential features such as: phenotype, resources, competition, heritage, mutation, and reinforcement, in as simple a way as possible. Still, the resulting model is not too easy to grasp with purely analytical tools, so we have also complemented those studies with stochastic simulations. We present a few results that both illustrates the usefulness of such a model, but also rises new biological questions about sympatric speciation
A recent study of a pair of sympatric species of palms on the Lord Howe Island is viewed as providing probably one of the most convincing examples of sympatric speciation to date. Here we describe and study a stochastic, individual-based, explicit genetic model tailored for this palms system. Overall, our results show that relatively rapid (, 50 000 generations) colonization of a new ecological niche, and sympatric or parapatric speciation via local adaptation and divergence in flowering periods are theoretically plausible if (i) the number of loci controlling the ecological and flowering period traits is small; (ii) the strength of selection for local adaptation is intermediate; and (iii) an acceleration of flowering by a direct environmental effect associated with the new ecological niche is present. We discuss patterns and time-scales of ecological speciation identified by our model, and we highlight important parameters and features that need to be studied empirically in order to provide ...
Thus the notion of an ecological niche is quite simple. It must be noted that succession can be managed. Community stability denotes the capacity of communities to stay unchanged as time passes.. There are two sorts of succession based on the kind of disturbance, primary and secondary succession. In mutualism, the connection between both organisms is interdependent. There are three major kinds of interdependence.. Mutualism and parasitism are two symbiotic relationships that sometimes happens in a particular ecosystem. Two organisms with the exact same ecological niche cant survive in the precise habitat in the exact long term. Sympatric speciation can happen for a multitude of explanations.. Inside this relationship the egret benefits greatly, but there isnt any apparent influence on the herbivore. There are over 20 other diverse species concepts, however. This classical definition is known as the biological species concept.. By way of example, in the Sonoran Desert, some yearly plants are ...
Darwin proposed that natural selection had a fundamental role in speciation, but did not elaborate much on the mechanism. It is now believed that much speciation is due not to natural selection, but to geographical isolation and genetic drift (allopatric speciation). However, natural selection is still seen to play a role in other speciation, such as speciation due to specialization on different hosts (Filchak et al. 2000), and natural selection drives incipient species to greater diversity (Presgraves et al. 2003 ...
Because of the very low frequency of recombination in bacteria (usually around the rate of mutation), the process of speciation appears simpler and faster in bacteria than in the highly sexual animals. There appears to be no need for either evolution of sexual isolation or geographic isolation in bacterial speciation. Indeed, microbial ecologists are finding evidence of sympatric speciation (among populations that are within easy dispersal range of one another) in nature and in laboratory evolution experiments.. We recently sought to test a novel hypothesis about the propensity for speciation in bacteria-that a lineage might split into two ecotypes that can coexist indefinitely (cladogenesis or speciation) faster than the lineage improves its adaptations without splitting (anagenesis). Our model system was a set of ten replicate communities of Bacillus subtilis growing in an extremely rich liquid medium. These communities were founded with two genetically marked strains derived from lab ...
Leiopotherapon unicolor is the most widespread freshwater fish species in Australia. A comprehensive allozyme and mitochondrial DNA 16S rRNA data set was assembled from 141 specimens of L. unicolor collected Australia-wide in order to test for cryptic speciation in this far-ranging species. Surprisingly, little genetic diversity was observed within L. unicolor and provided no evidence for the existence of cryptic species within this lineage. In contrast, a small sample set of L. aheneus used as the outgroup showed two highly divergent haplotypes strongly suggestive of cryptic speciation. L. unicolor has a number of ecological and life history attributes that may explain the lack of significant genetic divergence over substantial geographical distances. The occurrence of other widespread fish and crustacean species that also display only limited genetic diversity indicate that climate conditions more favourable to dispersal across central and northern Australia than is suggested by the extent of ...
Speciation generates discrete populations, which in turn is essential for maintaining novel adaptations during evolution. Hybrids between different species are usually inviable or sterile. Dobzhansky-Muller incompatibilities represent reciprocal-sign epistasis between inter-specific alleles and are widely accepted as a major driver of postzygotic reproductive isolation. They refer to deleterious genetic interactions between functionally diverged loci during the evolution of new species. They are widely accepted to cause hybrid sterility or inviability, the features associated with postzygotic reproductive isolation. The evolution of speciation genes is generally thought to be driven by adaptive evolution. Identifying these genes will provide more information about how speciation occurs. One of the main challenges in speciation genetics is that speciation events can normally not be observed and therefore data from present-day species are confronted statistically with competing hypotheses about ...
The name Phoberus capensis (Scholtz) is applied to a small flightless, keratinophagous beetle endemic to the Cape Floristic Region of South Africa. Its gross distribution stretches from roughly 1000 km from the Cederberg (S32°2422 E19°0450) to Grahamstown (S33°2007 E26°3250). The populations are spatially discrete, restricted to relict forests of the southern Cape and disjunct high montane refugia of the Cape Fold Mountains. We test the hypothesis that there is more than one distinct species nested within the name P. capensis. Phylogenetic relationships among populations were inferred using molecular sequence data. The results support three distinct evolutionary lineages, which were also supported by morphological characters. Divergence time estimates suggest Pliocene-Pleistocene diversification. Based on these results, it is suggested that the P. capensis lineage experienced climatically-driven allopatric speciation with sheltered Afrotemperate forests and high mountain peaks ...
Insects represent the worlds largest group of organisms, comprising over 900 000 described species, which is about 70% of all animal species [1]. Their species richness and biological diversity make insects key players in almost every terrestrial ecosystem. Many explanations for this hyperdiversity focus on the ecological niche and on ecological speciation [2]. Central to the concept of ecological speciation is that populations of the same species become genetically isolated because they specialize in different ecological niches [3-5]. This is assumed to result in the evolution of new species owing to restricted gene flow between populations, in allopatry as well as in sympatry [6]. One problem with the concept of ecological speciation is that it must be initiated by the switch of particular individuals of a population to a new ecological niche (e.g. a new host in herbivorous or parasitoid insects) to which they are not yet adapted. It is unclear why the offspring of these pioneers should ...
Rapporteur: Chris B. Cameron. Tricia Abe began her lecture by asking How do genetic drift and selection interact to produce new species? That is, is speciation a by-product of adaptation or do adaptive differences accumulate after genetic reorganization has occurred in a founder event? Viewing speciation in a historical context we see that Darwin (1859) was the first to recognize lineage splitting in The Evolution of Species, but he didnt address the underlying mechanism of speciation. Fisher (1918) documented the accumulation of new and favorable mutations in a population, and that adaptation produces genetic differences as a side effect. In 1931 Wright noticed that the non adaptive drift in small stable populations is sufficient to favor gene combinations that are unlikely to occur in larger populations, and that eventually this drift would become hard wired by natural selection. In 1940 Mayr formulated the biological species concept and by 1954 recognized that random genetic drift and ...
Author Summary Speciation, the process by which one species splits into two, involves reproductive barriers between previously interbreeding populations. The question of how speciation occurs has rightly occupied the attention of biologists since before Darwins
Many biodiversity hotspots are located in montane regions, especially in the tropics. A possible explanation for this pattern is that the narrow thermal tolerances of tropical species and greater climatic stratification of tropical mountains create more opportunities for climate-associated parapatric or allopatric speciation in the tropics relative to the temperate zone. However, it is unclear whether a general relationship exists among latitude, climatic zonation and the ecology of speciation. Recent taxon-specific studies obtained different results regarding the role of climate in speciation in tropical versus temperate areas. Here, we quantify overlap in the climatic distributions of 93 pairs of sister species of mammals, birds, amphibians and reptiles restricted to either the New World tropics or to the Northern temperate zone. We show that elevational ranges of tropical- and temperate-zone species do not differ from one another, yet the temperature range experienced by species in the ...
From Campbell, (p. 446): 4 different ways of putting it... ...a species [is] a population or group of populations whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring, but who cannot produce viable, fertile offspring with members of another species.. ...a species is the largest unit of population in which genetic exchange is possible, and that is genetically isolated from other such populations. Members of a biological species are united by being reproductively compatible, at least potentially. ...the biological species concept hinges on reproductive isolation, with each species isolated by factors (barriers) that prevent interbreeding, thereby blocking genetic mixing with other species.. From Freeman & Herron (1998) Evolutionary Analysis, Prentice Hall, Upper Saddle River. p. 314. 1. Species consist of groups of interbreeding populations. 2. Species are fundamental unit of evolution. 3. Species share a distinguishing ...
Simulations have shown that the spatial location of initial phage invasion may lead to different evolutionary scenarios. Phage infection decreases the speciation rate by more than one order as far as intensified selection blocks the origin of novel viable populations/species, which could carve out potential ecological niches. The dependence of speciation rate on the invasion node location varied on the time of invasion. Speciation rate was found to be lower when the phage invaded fully formed community of sedentary cells (at middle and late times) at the species-rich regions. This is especially noticeable in the case of late-time invasion.. Our simulation study has shown that phage infection affects evolution of microbial community slowing down speciation and stabilizing the system as a whole. This influencing varied in its efficiency depending on spatially-ecological factors as well as community state at the moment of phage invasion.. Keywords: Microbial community, Bacteria, Archaea, ...
Sexual reproduction with meiosis exists in all fungal phyla, except the Deuteromycota. It differs in many aspects from sexual reproduction in animals or plants. Many differences also exist between fungal groups and have been used to discriminate fungal clades and species based on morphological differences in sexual structures and reproductive strategies. Experimental crosses between fungal isolates can also be used to identify species based on biological species concepts. The major fungal clades have initially been delineated based on the morphology of their sexual structures and spores; for example, the spore-containing structures, asci and basidia, can be used in the identification of ascomycetes and basidiomycetes, respectively. Many fungal species have elaborate vegetative incompatibility systems that allow mating only between individuals of opposite mating type, while others can mate and sexually reproduce with any other individual or itself. Species of the former mating system are called ...
Sherry, Jessica Lynne, Ecological Divergence Among Extremely Close Relatives in Bacillus (2013). Honors Theses - All. 1103 ...
Fads happen in science, with a caveat that they arent always irrational exuberance: there are research topics that genuinely have value, but which nevertheless have a limited lifespan. Ill give an example: When I was a beginning graduate student, Dolph Schluter [for whom I have immense respect] had recently started publishing a series of papers on ecological speciation, along with his Ecology of Adaptive Radiations book which I heartily recommend. The core innovation here was that ecology plays a role in (1) driving trait divergence between populations that leads incidentally to mating isolation, and (2) eliminating poorly-adapted hybrids. Both ideas can be found in the literature of course, few ideas are truly 100% new. But what Dolph did was to crystallize the idea in a simple term, clearly explained, and solidly justified with data, making it compelling. And suddenly everyone wanted to study ecological speciation, it seemed to me. There was a rapid rise in publications (and reviews) on the ...
The simulations use an agent-based population model that consists of haploid and hermaphroditic individuals characterized by a binary string of B loci. Reproduction is restricted by a mating area determined by a spatial distance, S, and a genetic distance, G, beyond which other individuals are not considered potential mates. Reproductive isolation caused by this mechanism can be considered a multilocus generalization of the Bateson-Dobzhansky-Muller model whereby individuals accumulate genetic incompatibilities without the population passing through an adaptive valley (22). Reproductive success depends on the number of genetic differences between the individuals attempting mating, without affecting the fitness of the individuals themselves (21). The genetic distance between two individuals is the number of differing loci along their strings. The geographical space is represented by a 128 × 142 lattice with barriers defined by sites that cannot be occupied by individuals (Fig. S1). The remaining ...
In my book Speciation, written with Allen Orr, we give some estimates about how long it takes to make a new species. These estimates vary, of course. In the case of speciation that involves instantaneous genome doubling, as in auto- or allopolyploidy, a new hybrid species can arise in as few as three generations. But…
Slide set: Biological Evolution - Modes of Speciation. Learn about speciation (the formation of new species) and how populations evolve genetic distinctiveness and become reproductively separate.
Slide set: Biological Evolution - Modes of Speciation. Learn about speciation (the formation of new species) and how populations evolve genetic distinctiveness and become reproductively separate.
There is a large body of work evidencing the necessity to evaluate chemical speciation dynamics of trace metals in solution for an accurate definition of their bioavailability to microorganisms. In contrast, the integration of intracellular metal speciation dynamics in biouptake formalisms is still in its ea
Background: Biology employs different species concepts - the classical morphological concept, introduced by Carl v. Linné, is based on similarity in shape and originally was conceived without any evolutionary model: Linné believed, as most scientists of his time, into species constancy, because God has created the species as they are. As a logical consequence of evolution theory, species were later defined as genetic entities - according to Mayr and Dobzhansky, a species is just a group of individuals that exchange genes and are separated from other groups by propagation barreers. As pointed out in the lecture, both concepts are not really representing the situation in plants very appropriately. The search for a third, unifying, species concept applicable to plants, is still ongoing. The challenge for each species concept are the transitions between species, the cases, where a new species is just in the process to be born (incipient speciation). The Lamiaceae are something like a test tube to ...
Lu Han, Hiroyuki Koike, Praneet Chaturvedi, Keishi Kishimoto, Kentaro Iwasawa, Kirsten Giesbrecht, Phillip C Witcher, Alexandra Eicher, Talia Nasr, Lauren Haines, John M Shannon, Mitsuru Morimoto, James M Wells, Takanori Takebe, Aaron M Zorn
RPM points out that the most recent issue of Heredity tackles the issue of the genetics of speciation. Heres an interesting thing Ive noted, there are two ways to look at species questions. First, there are the taxonomists, who have been strongly influenced by the cladist revolution. They take a big picture philosophical view, and are obviously greatly concerned with process in terms of classification and demarcation. In contrast, there are the evolutionary geneticists who tend to be less interested in species qua species, as opposed to the process of genetic differentiation. In other words, for the latter camp species discussions are simply an ends toward elucidating the evolutionary dynamics of populations. The taxonomists in contrast are focused on species as the ends for generating their systems of evolutionary relationships. The Neandertal introgression story should make it clear Im interested in the dynamics of evolutionary processes, not any rigorous species classification ...
Testing the chromosomal speciation hypothesis for humans and chimpanzees.: Fixed differences of chromosomal rearrangements between isolated populations may prom
Speciation. Gradualism is one of two theories about the pace of evolutionary change. It was the prevailing the idea that species slowly change through a series of intermediate forms. However, there were gaps in the fossil record that did not support the theory. Punctuated equilibrium holds that long periods of relative stability in a species are punctuated by periods of rapid evolution. According to this theory, gaps in the fossil record are not gaps at all, as there was no long sequence of intermediate forms. Events such as geographic isolation and the opening of new niches within a shared geographic range can lead to rapid speciation ...
Mimicry has had a significant historical influence as a tractable system for studying adaptation and is known to play a role in speciation. Here, we discuss recent theoretical treatment of adaptive walks to local adaptive peaks and contrast this with the adaptive landscape of mimicry. Evolution of n …
Find speciation sampling articles on Environmental XPRT, the worlds largest environmental industry marketplace and information resource.
Get the latest speciation sampling news on Environmental XPRT, the worlds largest environmental industry marketplace and information resource.
New regulatory mandates require elemental analysis of many toxic metals and nutritional elements. Learn how combining the power of IC and ICP-MS to deliver speciation analysis has made it feasible to uncover complete chemical species information.
Hitrik M, Pisman Y, Wittstock G, Mandler D. Speciation of nanoscale objects by nanoparticle imprinted matrices. NanoscaleNanoscale. 2016;8 (29) :13934 - 13943.
My apologies if someone here has mentioned this article already: Basically, this was...
Many species today exist right on this cusp of a speciation event, and are called ring species. To put it very briefly, population A can interbreed with population B, which can interbreed with population C, but A and C cant interbreed. If B didnt exist, A and C would thus be classified as different species. What they actually represent is a species that is beginning to diverge into two new species, but the intermediate form (in this case, population B) hasnt died out yet. This is a very brief desciption but you can read here for more details ...
This covers rapid speciation, punctuated equilibrium and evolution by means other than natural selection. It covers how scientists use molecular techniques.
Gilead Sciences has been dealing with a slowdown for its hep C superstars Sovaldi and combo drug Harvoni, with prescriptions for the drugs petering off during the second quarter and analysts expecting things to continue in the same vein. As predicted the companys lagging momentum continued into Q3, with sales growth for its hep C treatments staying flat despite beats on earnings.
When God created the kinds, He frontloaded them with genetic differences-with the potential to form all sorts of new species and varieties.
The boom in analytical methods for determining the distribution of an element between its different chemical forms is charted by Andy Extance
DI-fusion, le Dépôt institutionnel numérique de lULB, est loutil de référencementde la production scientifique de lULB.Linterface de recherche DI-fusion permet de consulter les publications des chercheurs de lULB et les thèses qui y ont été défendues.
Greetings, Thanks for taking the time to look at my post. Ive run into an issue with my computer to which I cant remedy. A few things have begun...
Martínez-Garrido J, Serrão EA, Engelen AH, Cox CJ, García-Murillo P, Gonzalez-Wangüemert M. Multilocus genetic analyses provide insight into speciation and hybridization in aquatic grasses, genus Ruppia. Biological Journal of the Linnean Society. 2016;117(2):177 - 191. doi:10.1111/bij.12666 ...
Since Darwin, researchers have made tremendous progress towards understanding how ecological, genetic and evolutionary factors acting within species lead to the evolution of reproductive isolation and ultimately the origin of new species (Coyne & Orr 2004). One problem that remains largely unresolved concerns the evolution of intrinsic postzygotic isolation. Investigating early stages in the evolution of postzygotic isolation in species, where alleles underlying postzygotic isolation are still polymorphic, is one promising approach.. Previous studies of postzygotic isolation between M. guttatus and M. nasutus have found reduced seed germination and male infertility in hybrids (Vickery 1956, 1973, 1978; Fishman & Willis 2001, 2006; Martin & Willis 2007). Vickery (1956, 1973, 1978) and Sweigart et al. (2007) provided evidence that postzygotic isolation within and among populations of both species varied geographically, though biometrical line crosses were not used to determine the genetic basis. ...
Coyne and Orr found that mating discrimination (premating isolation) evolves much faster between sympatric than allopatric Drosophila species pairs. Their meta-analyses established that this pattern, expected under reinforcement, is common and that Haldanes rule is ubiquitous in Drosophila species divergence. We examine three possible contributors to the reinforcement pattern: intrinsic postzygotic isolation, dichotomized as to whether hybrid males show complete inviability/sterility; host-plant divergence, as a surrogate for extrinsic postzygotic isolation; and X chromosome size, whether roughly 20% or 40% of the genome is X-linked. We focus on young species pairs with overlapping ranges, contrasted with allopatric pairs. Using alternative criteria for sympatry and tests that compare either level of prezygotic isolation in sympatry or frequency of sympatry, we find no statistically significant effects associated with X chromosome size or our coarse quantifications of intrinsic postzygotic ...
Sympatric speciation is today generally viewed as plausible, and some well-supported examples exist, but its relative contribution to biodiversity remains to be established. We here quantify geographic overlap of sister species of heliconiine butterflies, and use age-range correlations and spatial simulations of the geography of speciation to infer the frequency of sympatric speciation. We also test whether shifts in mimetic wing colour pattern, host plant use and climate niche play a role in speciation, and whether such shifts are associated with sympatry. Approximately a third of all heliconiine sister species pairs exhibit near complete range overlap, and analyses of the observed patterns of range overlap suggest that sympatric speciation contributes 32 %-95 % of speciation events. Müllerian mimicry colour patterns and host plant choice are highly labile traits that seem to be associated with speciation, but we find no association between shifts in these traits and range overlap. In contrast,
The biologist Ernst Mayr championed the concept of ring species, claiming that it unequivocally demonstrated the process of speciation.[10] A ring species is an alternative model to allopatric speciation, illustrating how new species can arise through circular overlap, without interruption of gene flow through intervening populations…[11] However, Jerry Coyne and H. Allen Orr point out that rings species more closely model parapatric speciation.[8]. Ring species often attract the interests of evolutionary biologists, systematists, and researchers of speciation leading to both thought provoking ideas and confusion concerning their definition.[12] Contemporary scholars recognize that examples in nature have proved rare due to various factors such as limitations in taxonomic delineation[13] or, taxonomic zeal[10]-explained by the fact that taxonomists classify organisms into species, while ring species often cannot fit this definition.[12] Other reasons such as gene flow interruption from ...
Abstract Two of the remaining coregonine species in Lake Ontario, cisco (Coregonus artedi) and lake whitefish (C. clupeaformis), spawn in Chaumont Bay, NY. Larvae co-occur in the spring but are difficult to distinguish morphologically. We applied genetic species identification using microsatellite DNA loci of 268 larvae from known locations in nearshore and offshore habitats in Chaumont Bay to determine the extent of mixing of these species in each habitat. Cisco dominated (95% of larvae) the larvae in offshore habitats and lake whitefish dominated (84%) in nearshore habitats, where seven of eight putative hybrids occurred. Habitat segregation between these two species at the larval stage has implications for productivity estimates. Discrimination between cisco and lake whitefish larvae helps to characterize habitat and basic life history needs and to focus research collections. Genetic species identification should be applied to larger samples of larvae to evaluate changes in larval distributions and
TY - JOUR. T1 - Gene flow between sexual and asexual strains of parasitic wasps. T2 - A possible case of sympatric speciation caused by a parthenogenesis-inducing bacterium. AU - Adachi-Hagimori, Tetsuya. AU - Miura, Kazuki. AU - Abe, Yoshihisa. PY - 2011/6. Y1 - 2011/6. N2 - Sympatric speciation is strictly defined as the emergence of two species from a population in which mating has been random with respect to the place of birth of the mating partners. Mathematical models have shown that sympatric speciation is possible, but very few examples have been documented in nature. In this article, we demonstrate that arrhenotokous and thelytokous strains of a parasitic wasp, Neochrysocharis formosa, speciated sympatrically through infection by a symbiotic bacterium Rickettsia for the following reasons: First, Rickettsia infection was detected in all of the thelytokous strains collected throughout Japan. Second, the arrhenotokous and thelytokous strains have been collected sympatrically. Third, ...
Hybrid speciation is an example of sympatric speciation that can occur in plants.. Interspecies hybrids are usually sterile because the chromosome pairs, which consist of one chromosome from one species and another from the second species, do not segregate regularly at meiosis. When a hybrid species evolves, sterility may be overcome by polyploidy: the chromosome numbers are doubled. Each chromosome pair at meiosis contains two chromosomes from one species, and regular segregation is restored. Polyploidization is encouraged by applying the chemical colchicine in the commercial production of new species, but it can also occur naturally at a low rate. In this case, a new hybrid species may evolve. The polyploidy hybrids are interfertile among themselves, but reproductively isolated (by the mismatch in chromosome numbers) from the parental species; they are therefore well defined new species.. Many popular species of flower such as tulips (opposite) and orchids are created through artificial ...
Once the basis is ready, we can run the model. Below I am going to focus on some of the results and at the end I am going to attach the complete output file as TXT. you can download an play with the txt if you like:. Part 1 Result: This part gives you the some of the important parameters. First of all, the model has predicted a pH of 8.34 for the sea water. In reality the pH varies between 7.8 to 8.5 depending on the place of sea water collection. Secondly, the CBE is 0.04%. This again tells you that the chemical analysis of the sea water was great. It gives you the carbonate alkalinity 122.22 mg/kg soln as CaCO3 and also tells you that you have a Na-Cl water.. ...
Aquilegia formosa and Aquilegia pubescens are two closely-related species belonging to the columbine genus. Despite their morphological and ecological differences, previous studies have revealed a large degree of intercompatibility as well as little sequence divergence between these two taxa, and the genetic mechanisms underpinning reproductive isolation remain unknown. In order to assess the feasibility of a full genome scan for speciation genes, inter- and intraspecific patterns of variation were compared for 9 nuclear loci; it was concluded that the two species were practically indistinguishable at the level of DNA sequence polymorphism, indicating either very recent speciation or continued gene flow. As a comparison, the variation at two loci was analyzed across 30 other Aquilegia species, revealing slightly more differentiation among taxa and evidence for isolation by geographic distance (which was not the case on a more local geographic scale).; The extremely low levels of genetic ...
Population boundaries are largely determined by local environment, the strength of barriers to migration, and the organisms inherent dispersal abilities. The interaction among these and genetic factors determines the potential for evolutionary divergence, and is at the heart of our understanding of ecological adaptation and ongoing speciation processes. When individuals can easily cross barriers between suitable habitat patches, gene flow acts to homogenize most neutral genetic diversity and may swamp the effects of any local phenotypic selection whereas low levels of migration may facilitate ecological divergence, even when selection is modest. Evolutionary divergence through fine-scale geographic isolation is believed to be one of the main mechanisms promoting speciation in the cichlid radiations of the African Great Lakes [1-3]. Many lake species are extreme local endemics, with distributions limited to small patches of ecologically distinct habitat. Many narrowly endemic cichlid species are ...
I will argue that Drosophila geneticists are not so much interested in finding speciation genes, but rather interested in understanding the genetics of speciation. To do so requires finding mutations that allow the species boundary to be surmounted. As I have mentioned previously, good species are reproductively isolated, preventing any genetical analysis of the factors that lead to this isolation. Mutations in the speciation genes (especially the extremely useful Hybrid Male Rescue mutation), however, allow researchers to cross individuals from different species and study the genetics of speciation.. Geneticists like to find generalities. That is why we study model organisms; they are easy to work with in a laboratory setting and allow us to extend our discoveries regarding molecular biology, cellular function, development, physiology, etc to other related taxa (both closely related and more distant relatives). Wilkins makes a valid point that it is difficult to generalize discoveries ...
Cant speak for others but here at Uncommon Descent, we have been thinking that for quite some time. Were not shocked but we are annoyed when discredited textbook Darwinism is treated as the norm and the true state of affairs is treated as a big surprise.. See also: Bale monkeys more closely related to sister species than same species in different locationsThe biological species concept is yet another textbook dead zone.. Girl got mostly a double set of her dads genes, is almost a twin. She has some problems but she is 11 years old. Yes, that was the sound of another lectern splintering in the near distance.. Almost one in five genes coding status is unresolved Researchers: We believe that the three reference databases currently overestimate the number of human coding genes by at least 2000, complicating and adding noise to large-scale biomedical experiments.. Do all genes affect every complex trait? Veronique Greenwood: The roots of many traits, from how tall you are to your susceptibility ...
Darren has published a review of sex chromosomes evolution and speciation in birds and other ZW systems. This is an invited submission for a special issue of Molecular Ecology, on Sex Chromosomes and Speciation.. Heres the citation and link:. Irwin, D.E. 2018. Sex chromosomes and speciation in birds and other ZW systems. Molecular Ecology, online Early View: ...
Sympatric and parapatric speciation refer to theorigin of biological species in the absence of complete geographic isolation between the diverging taxa
TY - JOUR. T1 - Strikingly variable divergence times inferred across an Amazonian butterfly suture zone. AU - Whinnett, Alaine. AU - Zimmermann, Marie. AU - Willmott, Keith R.. AU - Herrera, Nimiadina. AU - Mallarino, Ricardo. AU - Simpson, Fraser. AU - Joron, Mathieu. AU - Lamas, Gerardo. AU - Mallet, James. PY - 2005/12/7. Y1 - 2005/12/7. N2 - Suture zones are areas where hybrid and contact zones of multiple taxa are clustered. Such zones have been regarded as strong evidence for allopatric divergence by proponents of the Pleistocene forest refugia theory, a vicariance hypothesis frequently used to explain diversification in the Amazon basin. A central prediction of the refugia and other vicariance theories is that the taxa should have a common history so that divergence times should be coincident among taxa. A suture zone for Ithomiinae butterflies near Tarapoto, NE Peru, was therefore studied to examine divergence times of taxa in contact across the zone. We sequenced 1619 bp of the ...
In this project we will use the comimetic, sympatric and phylogenetically close species H. melpomene malleti and H. timareta florencia to determine if chemical signals act as reproductive isolation barriers between them. If this is the case, the causal loci of the production and perception of these chemical signals will be determined either by mapping in controlled crosses or by evaluation of genotype-genotype association in natural populations. The results derived from this project will be of great impact in the field of speciation, helping to understand the genetic mechanisms of reproductive isolation in early stages of speciation, particularly in cases where differentiation occurs in the presence of gene flow ...
Levels of genetic differentiation between populations can be highly variable across the genome, with divergent selection contributing to such heterogeneous genomic divergence. For example, loci under divergent selection and those tightly physically linked to them may exhibit stronger differentiation than neutral regions with weak or no linkage to such loci. Divergent selection can also increase genome-wide neutral differentiation by reducing gene flow (e.g. by causing ecological speciation), thus promoting divergence via the stochastic effects of genetic drift. These consequences of divergent selection are being reported in recently accumulating studies that identify: (i) outlier loci with higher levels of divergence than expected under neutrality, and (ii) a positive association between the degree of adaptive phenotypic divergence and levels of molecular genetic differentiation across population pairs [isolation by adaptation (IBA)]. The latter pattern arises because as adaptive divergence ...
In Speciation in Birds, Trevor Price, a University of Chicago professor and leading expert in the field, has written the most authoritative and modern synthesis on the subject to date. In clear and engaging prose and through beautiful illustrations, Price shows us why the field is as exciting and vibrant as ever. He evaluates the roles of natural selection and sexual selection. He asks how speciation contributes to some of the great patterns in species diversity such as the large number of species in the tropics, and the many endemic species on isolated islands. Throughout the book, Price emphasizes the integration of behavior, ecology, and genetics.
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
Recent developments are providing exciting new insights into the evolutionary dynamics of species diversification and the importance of evolutionary radiations, or rapid episodes of lineage diversification. The aim of this meeting is to explore questions about where, when and why plant evolutionary radiations happen, and how they proceed. The meeting will bring together contributions spanning: (i) new models of species diversification, including paleodiversity and trait evolution, and the increasingly sophisticated and powerful tools available for testing hypotheses about diversification trajectories and their causes; (ii) the proliferation of new molecular phylogenetic data, for more and larger plant clades spanning broader taxonomic, geographical and temporal levels, as well as opportunities for unprecedented phylogenetic resolution of rapidly evolving clades coming from genome-scale DNA sequence data; (iii) assembly of more comprehensive species geographic distribution, functional and life ...
Polyploidy, the doubling of genomic content, is a widespread feature, especially among plants, yet its macroevolutionary impacts are contentious. Traditionally, polyploidy has been considered an evolutionary dead end, whereas recent genomic studies suggest that polyploidy has been a key driver of macroevolutionary success. We examined the consequences of polyploidy on the time scale of genera across a diverse set of vascular plants, encompassing hundreds of inferred polyploidization events. Likelihood-based analyses indicate that polyploids generally exhibit lower speciation rates and higher extinction rates than diploids, providing the first quantitative corroboration of the dead-end hypothesis. The increased speciation rates of diploids can, in part, be ascribed to their capacity to speciate via polyploidy. Only particularly fit lineages of polyploids may persist to enjoy longer-term evolutionary success. ...
Citation: Hafner, S.D., Meisinger, J.J., Mulbry III, W.W., Ingram, S.K. 2012. A pH-based method for measuring gaseous ammonia. Nutrient Cycling in Agroecosystems. 92(2):195-205. Interpretive Summary: Ammonia emissions from agricultural systems contribute to poor air quality and pollution of terrestrial and aquatic ecosystems. Various approaches are used to measure and better understand ammonia emission from agricultural systems. A common method for measuring emission or gaseous concentration is to trap ammonia in an acid solution, and later measure the total ammonia content of the solution. In this paper, we present a modification of this method, where the ammonia content of the acid solution is determined indirectly by measuring the solution pH. Ammonia content is calculated from pH by application of a chemical speciation model. The method is rapid and non-destructive, and so can be applied repeatedly to the same acidic solution at a high frequency. Testing of the method through laboratory ...
inbreeding, if not totally selfing, and thus does not ex- perience sexual recombination. The equivalence of the number of genotypes with the number of hybrid origins, therefore, appears to be a valid assumption in this species.) Alternatively, the existing populations could be remnants of a once more continuous, southern Rocky Mountain metapopulation, most of which has gone extinct. Even under the latter scenario, however, one must invoke dis- persal from a single original point of hybridization with subsequent reduction in population size.. The genetic identities among the continental U.S. pop- ulations may be particularly significant in unraveling the biogeographic history of this species in light of its tetra- ploid nature. Werth and Windham (1991) proposed a model of speciation of allopatric populations of polyploid pteridophytes involving reciprocal silencing of alternate alleles at homoeologous loci, and several empirical studies have documented such reciprocal silencing in disjunct, ...
When mismatch-binding activity is enhanced and SOS induction is blocked (Fig. 3, lexA3 pmutSL) the genetic isolation is extremely sensitive to sequence divergence, creating an efficient genetic barrier between closely related strains such as E. coli K-12 and E. coli C, or E. coli K-12 and Sh. flexneri. This corresponds formally to a speciation event. On the other hand, inactivation of MMR and overproduction of RecA (Fig. 3, mutS recAo98) relaxes the genetic barrier in the range of divergence examined in these experiments, allowing efficient recombination between bacteria as diverged as E. coli and S. typhimurium. For example, the same frequency of recombination, ≈3 × 10−3 (Fig. 3), can be found between E. coli K-12, Sh. flexneri, and S. typhimurium donors and E. coli K-12 recipient, depending solely on the genetic background of the recipient.. This shows that the effectiveness of a genetic barrier is not a constant of a given species, raising the question of its regulation.. The MMR and SOS ...
Aim We test whether populations of the Mesoamerican azure-crowned hum- mingbird, Amazilia cyanocephala (Trochilidae), located east and west of the Isthmus of Tehuantepec are genetically, morphologically and environmentally differentiated and examine the relative role of drift and selection in driving diversification. Location Mexico. Methods We sequenced the mitochondrial ATPase-6 and ATPase-8 genes and the control region of 130 individuals collected throughout the range of the spe- cies in Mexico. Population genetic methods and coalescent tests were used to reconstruct the phylogeography of the species. Morphological and niche varia- tion between genetic groups of A. cyanocephala were assessed. Results The data revealed two genetic groups separated by the Isthmus of Tehuantepec in the late Pleistocene (49,300-75,800 years ago), with the split occurring in the presence of gene flow. Deviations from demographic equilibrium were detected for the two genetic groups, indicating more recent ...
View Notes - ExampleExam1 from EEB 390 at University of Michigan. 2. Cladogenesis Essays [expect to have to respond to four essay questions - 16 pts each] Instructions : Respond to the following
We investigated the conditions for within-host adaptive diversification by expanding the theory of competitive speciation to macro-parasite species, and by confronting our theory to a comparative analysis of speciation rates in monogenean parasites.. Although the invasion fitness depends on parameters describing key features of the macro-parasite life history, we showed that it is typologically equivalent to those previously derived for non-parasite species as long as the mutants tend to colonize the same hosts as the residents. In contrast, when mutants randomly colonize host individuals, or when they tend to colonize less infected hosts, the fitness functions of parasites and non-parasites are no longer similar. As expected, differences between the distribution of mutants and residents promote mutant invasion. This is consistent with the well-known effect of spatial heterogeneity to promote coexistence between competitive species of mammals [52], birds [53], plants [54], fungi [55] as well as ...
The phylogenetic species concept defines a species as a group of organisms that shares a common ancestor and can be distinguished from other organisms that do not share that ancestor. As an analogy,...
Streamline Your Speciation Workflow Flyer Many modern laboratories, like yours, are expanding their analytical portfolio to include HPLC-ICP-MS for metal speciation to gain better insight about ion mobility, bioavailability, metabolism and toxicity. Our NexSAR™ HPLC-ICP-MS Speciation Solution brings together our inert NexSAR Speciation Analysis Ready HPLC system and the revolutionary NexION® ICP-MS in a seamless platform. Integrated using Clarity™ software, all levels of expertise are catered to through an intuitive solution with multi-user and multi-permission functionality.. ...
Streamline Your Speciation Workflow Flyer Many modern laboratories, like yours, are expanding their analytical portfolio to include HPLC-ICP-MS for metal speciation to gain better insight about ion mobility, bioavailability, metabolism and toxicity. Our NexSAR™ HPLC-ICP-MS Speciation Solution brings together our inert NexSAR Speciation Analysis Ready HPLC system and the revolutionary NexION® ICP-MS in a seamless platform. Integrated using Clarity™ software, all levels of expertise are catered to through an intuitive solution with multi-user and multi-permission functionality.. ...
Streamline Your Speciation Workflow Flyer Many modern laboratories, like yours, are expanding their analytical portfolio to include HPLC-ICP-MS for metal speciation to gain better insight about ion mobility, bioavailability, metabolism and toxicity. Our NexSAR™ HPLC-ICP-MS Speciation Solution brings together our inert NexSAR Speciation Analysis Ready HPLC system and the revolutionary NexION® ICP-MS in a seamless platform. Integrated using Clarity™ software, all levels of expertise are catered to through an intuitive solution with multi-user and multi-permission functionality.. ...
The knowledge of metal ion speciation is essential for predicting the exact toxicities of metal ion species in the environment. Metal ions can exist in various
McWilliams, A., Flanagan, J., Gutknecht, W., & Jayanty, R. K. (2003, April). Assuring Comparibility between Multiple X-ray Fluorescence Instruments used in the PM2.5 Chemical Speciation Program. Presented at , .. ...
Watch this video to learn how the Pulsar™ benchtop NMR can be used to determine meat speciation in food products. The fatty acid component of triglycerides found in animal tissue is known to differ between species and can be used to detect contamination and adulteration.
Elasticity of substitution and the slowdown of the Italian productivity . . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
SSD performance -- is a slowdown inevitable? ( Storage ) The recent revelation that Intel Corp.s consumer-class solid-state disk (SSD) drives suffer from fragmentation that can cause a significant performance degradation raises the question: Do all SSDs slow down with use over time?
The intimate associations between plants and the insects that eat them have helped define and shape both groups for millions of years. This pioneering volume is a comprehensive, up-to-date treatment of the evolutionary biology of herbivorous insects, including their relationships with host plants and natural enemies.
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I remember reading a while ago about an animal with a fairly large range. Animals in areas adjacent to each other were genetically similar enough to interbreeed with no problems, but animals from opposite ends of their range could not. I think they existed in semi-isolated populations but am not sure. Does anyone know what it is that Im thinking of ...
Daily News How Gaining and Losing Weight Affects the Body Millions of measurements from 23 people who consumed extra calories every day for a month reveal changes in proteins, metabolites, and gut microbiota that accompany shifts in body mass.. ...
The lability and mobility of Zn(II)-, Cd(II)-, Pb(II)-, and Cu(II)-humic acid complexes were studied using diffusive gradients in thin films (DGT). A unique feature of this research was (1) the use of
This is one of six different example models (all developed by Ted Eary of Enchemica) that illustrate how GoldSim can be used to carry out...
In chapter 3, The Sense of Sensibility, author Wendy Jones uses scenes from one of Jane Austens most celebrated novels to illustrate the functioning of the bodys stress response system.. 0 Comments. ...
Improving accuracy in the quantitation of overlapping, asymmetric, chromatographic peaks by deconvolution: theory and application to coupled gas chromatography atomic absorption spectromery ...
Ken Brown, Columnist at The Wall Street Journal, discusses the Chinese economy following better-than-expected GDP for the second quarter.
ISBN 3-443-26005-5 (3-443-26005-5) White M.J.D. (ed). Genetic mechanisms of speciation in insects. Symposia at the XIVth ... Check date values in: ,date= (help) White, M.J.D. (1978). Modes of speciation. Freeman. White M.J.D. and Webb G.C. Blattodea, ... His work was influential in the study of speciation in biology.[citation needed] White, M.J.D. (1937; 6th ed 1973). The ...
ISBN 0-387-52054-6 Hillig, Karl W. (2005). "Genetic evidence for speciation in Cannabis (Cannabaceae)". Genetic Resources and ... resulting in speciation. It remains controversial whether sufficient morphological and genetic divergence occurs within the ... In 2005, a genetic analysis of the same set of accessions led to a three-species classification, recognizing C. sativa, C. ... The patterns of genetic, morphological, and chemotaxonomic variation support recognition of C. sativa and C. indica as separate ...
Karl W. Hillig (2005). "Genetic evidence for speciation in Cannabis (Cannabaceae)". Genetic Resources and Crop Evolution. 52 (2 ... A recent genetic analysis included both the narrow-leaflet and wide-leaflet drug "biotypes" under C. indica, as well as ...
Johnson, Ned K.; Zink, Robert M. (1983). "Speciation in sapsuckers (Sphyrapicus): I. Genetic differentiation". The Auk. 100 (4 ... It has low genetic diversity; about half of that of most birds. In the United States, yellow-bellied sapsuckers are listed and ...
Johnson, Ned K.; Zink, Robert M. (October 1983). "Speciation in Sapsuckers (Sphyrapicus): Genetic Differentiation" (PDF). The ... Genetic analysis has shown that the red-naped sapsucker is a sister species with (and very closely related to) the red-breasted ... However, there are significant genetic differences between this species and the yellow-bellied sapsucker, and the American ...
Palumbi, Stephen R. (1994). "Genetic Divergence, Reproductive Isolation, and Marine Speciation". Annual Review of Ecology and ... multilevel selection and indirect genetic effects on response to genetic selection". Journal of Evolutionary Biology. 21 (5): ... The role of genetic drift is equivocal; though strongly supported initially by Dobzhansky, it was downgraded later as results ... Organisms inherit genetic material from their parents in the form of homologous chromosomes, containing a unique combination of ...
Baker, R.J.; Bradley, R.D. (2006). "Speciation in mammals and the Genetic Species Concept". Journal of Mammalogy. 87 (4): 643- ...
Phalolepis in Southern Italy: ongoing speciation or species overestimation? Genetic evidence based on SSRs analyses". ...
Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (2006). "Genetic evidence for complex speciation of humans and ... Lay summary - New York Times (2007-10-19). Stein, Richard A. (October 2015). "Copy Number Analysis Starts to Add Up". Genetic ... Callaway, Ewen (26 July 2012). "Hunter-gatherer genomes a trove of genetic diversity". Nature. doi:10.1038/nature.2012.11076. ... "Greenlandic Inuit show genetic signatures of diet and climate adaptation". Science. 349 (6254): 1343-1347. Bibcode:2015Sci... ...
May 2006). "Genetic evidence for complex speciation of humans and chimpanzees". Nature. 441 (7097): 1103-1108. Bibcode: ... fusing to form a genetic singular clonal colony that can cover hectares called a genet or just microscopical areas. For fungi, ...
Patterson, N; Richter, DJ; Gnerre, S; Lander, ES; Reich, D (2006). "Genetic evidence for complex speciation of humans and ... A broad study of African genetic diversity, headed by Sarah Tishkoff, found the San people had the greatest genetic diversity ... Genetic evidence has also been employed to resolve the question of whether there was any gene flow between early modern humans ... The genetic and archaeological evidence for this remains in question however. Homo habilis lived from about 2.8 to 1.4 Ma. The ...
Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (June 2006). "Genetic evidence for complex speciation of humans and ... do not statistically test their own null model of simple speciation before concluding that speciation was complex, and-even if ... There is evidence for a complex speciation process for the Pan-Homo split. This concerns times pre-dating the emergence of Homo ... All great apes have similar genetic structure. Chromosomes 6, 13, 19, 21, 22, and X are structurally the same in all great apes ...
Complex speciation and incomplete lineage sorting of genetic sequences seem to also have happened in the split between the ... Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (June 2006). "Genetic evidence for complex speciation of humans and ... do not statistically test their own null model of simple speciation before concluding that speciation was complex, and-even if ... 2006). Speciation between Pan and Homo occurred over the last 9 million years. Ardipithecus probably branched off of the Pan ...
Yamamichi, M; Gojobori J; Innan H. (January 2012). "An autosomal analysis gives no genetic evidence for complex speciation of ... "Genetic evidence for complex speciation of humans and chimpanzees". Nature. 441 (7097): 1103-1108. Bibcode:2006Natur.441.1103P ... Genetic tests frequently show that some of the offspring raised by a monogamous pair come from the female mating with an extra- ... Finally, the term genetic monogamy is used when DNA analyses can confirm that a female-male pair reproduce exclusively with ...
Wain, R. P. (1983). Genetic differentiation during speciation in the Helianthus debilis complex. Evolution 37(6) 1119-27. ...
An intermediate genetic distance may thus be most conducive to hybrid speciation. Experimental lab crosses support this ... April 2010). Walsh B (ed.). "Genetic evidence for hybrid trait speciation in heliconius butterflies". PLOS Genetics. 6 (4): ... Homoploid hybrid speciation Homoploid hybrid speciation is defined as the evolution of a new hybrid species with reproductive ... Wu C (2001). "The genic view of the process of speciation: Genic view of the process of speciation". Journal of Evolutionary ...
Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (June 2006). "Genetic evidence for complex speciation of humans and ... do not statistically test their own null model of simple speciation before concluding that speciation was complex, and-even if ... Wakeley J (March 2008). "Complex speciation of humans and chimpanzees". Nature. 452 (7184): E3-4, discussion E4. Bibcode: ... Wong, Kate (1 September 2014). "Tiny Genetic Differences between Humans and Other Primates Pervade the Genome". Scientific ...
A genetic dissection of the X chromosome for speciation gene". Hereditas. 114 (2): 189-95. doi:10.1111/j.1601-5223.1991.tb00323 ... It was shown that genetic changes in D. subobscura at these sites can be used as a possible tool to track global climate ... Dolgova, O.; Rego, C.; Calabria, G.; Balanyà, J.; Pascual, M.; Rezende, E. L.; Santos, M. (2010). "Genetic constraints for ... "Global Genetic Change Tracks Global Climate Warming in Drosophila subobscura". Science. 313 (5794): 1773-1775. Bibcode:2006Sci ...
This rapid speciation is both observed in plants and vertebrates. Rapid speciation is explained by the ecology and social ... Carson, H. L. (1987). The genetic system, the deme, and the origin of species. Annual review of genetics, 21(1), 405-423. Bush ... This is called allopatric speciation and is generally a slow process. On the contrary, sympatric speciation can be more rapid ... Primates, for example, have the second highest speciation rate among mammals, with one speciation event per lineage every 3 ...
These processes have been difficult to test until recently with advances in genetic modelling.[54] Speciation by sexual ... Genetic compatibility[edit]. Genetic compatibility refers to how well the genes of two parents function together in their ... However, the genetic compatibility model is limited to specific traits due to complex genetic interactions (e.g. major ... Speciation[edit]. For many years it has been suggested that sexual isolation caused by differences in mating behaviours is a ...
Genetic pollution Hybrid swarm Hybrid speciation Introgression Hybrizyme Endler, J. (1977). Geographic Variation, Speciation ... or speciation). Hybrid zones are useful in studying the genetics of speciation as they can provide natural examples of ... These are alleles that are normally rare in both species but, probably due to genetic hitchhiking on genes for hybrid fitness, ... Based on the fossil record and genetic marker studies the following chronology is used to explain the Canadian mussel hybrid ...
Genetic population structure indicates sympatric speciation of Lake Malawi pelagic cichlids. Proceedings of the Royal Society ... Molecular genetic studies suggest that Diplotaxodon species are all closely related and are ancestral to the more benthic- ... and earlier editions) Genner, M.J., Nichols, P., Shaw, P.W., Carvalho, G.R., Robinson, R.L. & Turner, G.F. (2008) Genetic ... Population genetic studies indicate that similar-looking forms with different male breeding colours represent distinct species ...
"Kinetic effects of temperature on rates of genetic divergence and speciation". PNAS. 103 (24): 9130-9135. Bibcode:2006PNAS.. ... "Genetic pollution: Uncontrolled escape of genetic information (frequently referring to products of genetic engineering) into ... Zaid, A. (1999). "Genetic pollution: Uncontrolled spread of genetic information". Glossary of Biotechnology and Genetic ... Genetic erosion and genetic pollution have the potential to destroy unique genotypes, threatening future access to food ...
"Kinetic effects of temperature on rates of genetic divergence and speciation". PNAS. 103 (24): 9130-9135. Bibcode:2006PNAS.. ... species with larger ranges may be more likely to undergo allopatric speciation, which would increase rates of speciation ( ... More research needs to be done to determine whether or not speciation rates actually are higher in the tropics. Understanding ... Weir, J.T.; Schluter, D. (2007). "The latitudinal gradient in recent speciation and extinction rates of birds and mammals". ...
The second process, speciation, is closely associated with cladogenesis. Speciation includes the actual separation of lineages ... Other factors such as selection or genetic drift will have such a significant effect on genetic material and physical traits ... When speciation does occur as different lineages branch off and cease to interbreed, a core group may continue to be defined as ... This is in contrast to cladogenesis-or speciation in a sense-in which a population is split into two or more reproductively ...
... homogenising effect on populations and prevents speciation through causing genetic admixture and blurring any distinct genetic ... allopatric speciation). The possibility that clines may be a precursor to speciation was therefore ignored, as they were ... As genetic admixture between the population increases with time however, the steepness of the cline is likely to decrease as ... The genetic or phenotypic trait in question always shows a steeper gradient between groups than within groups, as in continuous ...
Nevo E.; Bar-El C.; Bar Z (1983). "Genetic diversity, climatic selection and speciation of Sphincterochila land snails in ... The genetic variability within the 15-species genus Sphincterochila is predominantly due to differences in water availability. ...
Without genetic exchange, geographically and reproductively isolated populations may undergo genetic drift. Such speciation is ... Substantial evidence for speciation due to natal philopatry has been gathered in studies of island-nesting albatross. Genetic ... Speciation through natal philopatry is a self-reinforcing process. Once genetic differences are sufficient, different species ... Abbott, Cathryn L; Double, Michael C (2003). "Genetic structure, conservation genetics and evidence of speciation by range ...
"Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses". Molecular Ecology. 17 (11): 2691- ... CS1 maint: discouraged parameter (link) Weir, J. T.; D. Schluter (2004). "Ice sheets promote speciation in boreal birds". ... thought to have promoted speciation in many avian systems inhabiting the boreal forest of North America. The Pacific wren nests ...
If these genetic differences grow between different populations speciation events can occur. When this theory was first ... Genetic drift, or the result of a limited population size, can also cause a change in allele frequencies over time that can ... October 14, 2016). "Genetic drift, selection and the evolution of the mutation rate". Nature Genetics. 17 (11): 704-714. doi: ... Mutations occur at random and in the Darwinian evolution model natural selection acts on the genetic variation in a population ...
While schizophrenia is widely believed to be multifactorially genetic by biopsychiatrists, no characteristic genetic markers ... Castle would refine his model for speciation to allow for small variation to contribute to speciation over time. He also was ... then there is a strong chance that the disease is genetic[citation needed] and that the patient will also be a genetic carrier ... If a genetic cause is suspected and little else is known about the illness, then it remains to be seen exactly how many genes ...
Genetic drift. *Pagdaloy ng Gene. *Makroebolusyon. *Mikroebolusyon. *Mutasyon. *Natural na seleksiyon. *Speciation ...
Genetic analysis has shown that certain mallards appear to be closer to their Indo-Pacific relatives while others are related ... Over time, a continuum of hybrids ranging between almost typical examples of either species develop; the speciation process is ... Owing to their highly 'malleable' genetic code, mallards can display a large amount of variation,[36] as seen here with this ... Mallards are causing severe "genetic pollution" to South Africa's biodiversity by breeding with endemic ducks[113] even though ...
Speciation. *Taxonomy. Population genetics. *Biodiversity. *Gene flow. *Genetic drift. *Mutation. *Natural selection ...
"Genetic relationships of North American cardueline finches" (PDF). Condor 88 (4): 409-420. doi:10.2307/1368266 ... "Phylogeny and rapid Northern and Southern Hemisphere speciation of goldfinches during the Miocene and Pliocene Epochs" (PDF) ...
"Genetic Evaluation Results". Archived from the original on August 27, 2001.. *^ S1008: Genetic Selection and Crossbreeding to ... An essay on the close relationship between speciation, inbreeding and recessive mutations". Biology Direct. 6: 62. doi:10.1186/ ... "Genetic diversity and population genetic structure in the South American sea lion (Otaria flavescens)" (PDF). Department of ... There are genetic assays being scheduled for lions to determine their genetic diversity. The preliminary studies show results ...
... describes the genetic effect of a single gene on multiple phenotypic traits. The underlying mechanism is genes that ... Pleiotropic genes act as an arbitrating force in speciation. William R. Rice and Ellen E. Hostert (1993) conclude that the ... Sickle cell anemia is a genetic disease that causes deformed red blood cells with a rigid, crescent shape instead of the normal ... Kirkpatrick, Mark; Ravigné, Virginie (2002-03-01). "Speciation by Natural and Sexual Selection: Models and Experiments". The ...
It is also a notable case for studying sympatric speciation, as it appears to be diverging into two species currently.[2] ... These two strains have major genetic differences that are connected to the plants they feed on, even though both still exist in ... the same area (sympatric speciation). These two strains can be loosely categorized into a rice strain and a corn strain. This ...
These estimates are made using genetic mapping of plant chloroplasts.[12] A DNA study published in Nature in 2018 concludes ... A change in climate conditions during the Late Miocene (11.63 to 5.33 mya) resulted in a sudden speciation event. The species ... Citrus fruits clustered by genetic similarity, ternary diagram based on data from Curk, et al. (2016)[18] ... National Germplasm Resources Laboratory, Beltsville, Maryland: USDA, ARS, National Genetic Resources Program. Archived from the ...
a b Feder, J. L. (1998) "The apple maggot fly, Rhagoletis pomonella: flies in the face of conventional wisdom about speciation ... flies maintain their genetic integrity partly because of allochronic premating isolation from differently timed adult eclosion ... This constitutes a possible example of an early step towards the emergence of a new species, a case of sympatric speciation.[10 ... In Howard, D. J. & Berlocher, S. H. (Eds.) Endless Forms: Species and Speciation. New York, Oxford University Press. ISBN ...
遺傳重組會交換不同染色體或同一染色體的不同區域之間的基因,而打破遺傳連鎖,讓基因能夠自由組合,並降低遺傳便車效應(genetic hitchhiking)。這使得天擇更有效率,因此,重組率高的區域會保留較少有害突變、較多有利的等位基因、和較少DNA複製的 ... Nikolai P. Kandul
Jacob F; Monod J (June 1961). "Genetic regulatory mechanisms in the synthesis of proteins". J Mol Biol. 3 (3): 318-56. doi: ... Mitchell, Matthew W.; Gonder, Mary Katherine (2013). "Primate Speciation: A Case Study of African Apes". Nature Education ... Andrews, Christine A. (2010). "Natural Selection, Genetic Drift, and Gene Flow Do Not Act in Isolation in Natural Populations ... April 2010). "Analysis of genetic inheritance in a family quartet by whole-genome sequencing". Science 328 (5978): 636-9. ...
... though authors applying a genetic species concept have suggested it should be considered a separate species.[10] Essentially ... though they are very distinct evolutionarily and are probably the result of allopatric speciation, their distribution later ...
A 2015 genetic study by evolutionary biologist Emma Harrower and colleagues of C. violaceus and its closest relatives suggests ... "Long-distance dispersal and speciation of Australasian and American species of Cortinarius sect. Cortinarius". Mycologia. 107 ... There are some populations that seem to prefer deciduous trees and others that prefer pines, but no genetic divergence between ... found no genetic or ecological difference between the two taxa.[14] ...
Baillie BK, Belda-Baillie C A,, Silvestre V, Sison M, Gomez AV, Gomez ED, Monje V (2000). Genetic variation in Symbiodinium ... 74,0 74,1 Blank RJ, Trench RK (1985) Speciation and symbiotic dinoflagellates. Science 229:656-658 ... 32,0 32,1 Sampayo E, Dove S, LaJeunesse TC (2009) Cohesive molecular genetic data delineate species diversity in the ... Andras J P, Kirk NL, Harvell CW (2011) Range-wide population genetic structure of Symbiodinium associated with the Caribbean ...
Hammerstein, P. (2003). "Why is reciprocity so rare in social animals? A protestant appeal". The Genetic and Cultural Evolution ... which created a geographic barrier that caused the species to diverge through the process of allopatric speciation. Today, the ...
... loss of genetic diversity, and speciation in Mediterranean Quaternary refugia". Molecular Ecology. 16 (8): 1713-1727.. ... International Plant Genetic Resources Institute, Rome. ISBN 92-9043-229-2.. CS1-vedligeholdelse: Flere navne: authors list ( ... in southern Patagonia without genetic or spatial restriction". Molecular Biology and Evolution. 26 (4): 907-923.. ...
"Diversity and Genetic Structure of the Wood Ant Formica Lugubris in Unmanaged Forests". Ann. Zool. Fennici: 189-99.. ... Goropashnaya, Anna V.; Fedorov, Vadim B.; Pamilo, Pekka (2004). "Recent Speciation in the Formica Rufa Group Ants (Hymenoptera ... Gyllenstrand, N.; Seppa, P.; Pamilo, P. (2004). "Genetic Differentiation in Sympatric Wood Ants, Formica rufa and F. polyctena ...
Speciation[edit]. Hemipenes are also being used to study speciation among squamata, especially in identifying cryptic diversity ... Therefore, it is in their interest to mate with as many females as possible to increase their chance of passing on genetic ... Furthermore, females can also produce offspring that can feature genetic material from multiple males in a single clutch if she ... Booth, W.; Schuett, G. (2011). "Molecular genetic evidence for alternative reproductive strategies in North American pitvipers ...
The genetic, molecular and phenotypic consequences of selection for insecticide resistance". Trends in Ecology and Evolution. 9 ... *^ ... Evolution experiments with microorganisms: the dynamics and genetic bases of adaptation". Nat. Rev. Genet. 4 (6): 457-69. iunie ... Evolution experiments with microorganisms: the dynamics and genetic bases of adaptation". Nature Reviews Genetics. 4: 457-469. ...
A genetic basis for instinctive behavioural traits among non-human species, such as in the above example, is commonly accepted ... Genetic mouse mutants illustrate the power that genes exert on behaviour. For example, the transcription factor FEV (aka Pet1 ... Individual genetic advantage fails to explain certain social behaviors as a result of gene-centred selection. E.O. Wilson ... Heritability isn't an index of how genetic a trait is. A great deal of time has been wasted in the effort of measuring the ...
Geographical isolation often leads to speciation. In plants, polyploidy must be included in any view of speciation. ... There is clear proof that much of development is closely controlled by special genetic systems involving hox genes.[23][24][25] ... Big changes do occur, from time to time, but they are very rare.[4] Genetic drift is usually less important than natural ... Embryos, genes and evolution: the developmental-genetic basis of evolutionary changes. Macmillan, N.Y. ...
About 800 million years ago,[37] a minor genetic change in a single molecule called guanylate kinase protein-interaction domain ... whereas the micronucleus is used for sexual reproduction with exchange of genetic material. Slime molds syncitia form from ... "Genetic Flip Helped Organisms Go From One Cell to Many". New York Times. Retrieved 7 January 2016 ...
Eva., Jablonka, (2005) Evolution in four dimensions : genetic, epigenetic, behavioral, and symbolic variation in the history of ... Lande, R (1989) «Fisherian and Wrightian theories of speciation» Genome 31 (1): 221-7 2687093 . Noiz kontsultatua: 2010-06-09. ... Ingelesez) Peters, Andrew D.; Otto, Sarah P. (2003) «Liberating genetic variance through sex» BioEssays (6): 533-537 doi: ... Radding, Charles M. (1982-12-01) «Homologous pairing and strand exchange in genetic recombination» Annual Review of Genetics (1 ...
As the marine microbiota recovered, however, it is thought that increased speciation of benthic foraminifera resulted from the ... suggests that the decrease in diversity was caused more by a sharp increase in extinctions than by a decrease in speciation.[27 ...
... Genetic Stock Center (University of South Carolina). *Deer Mice Fact Sheet from the National Pest Management ... speciation, chromosomes, genetics, ecology, population genetics, and evolution in general. They are also useful for researching ... The Peromyscus Genetic Stock Center at the University of South Carolina was established by Professor Wallace Dawson in 1985 to ... and the color of their coats is exhibited in these genetic lines. ...
Newton, Ian (2003). The Speciation and Biogeography of Birds. Amsterdam: Academic Press. p. 463. ISBN 0-12-517375-X.. ... The vast majority of bird species are socially monogamous (referring to social living arrangement, distinct from genetic ... It was earlier thought that this high diversity was the result of higher speciation rates in the tropics; however recent ... Weir, Jason T.; Schluter, D (2007). "The Latitudinal Gradient in Recent Speciation and Extinction Rates of Birds and Mammals". ...
Schowalteria is a Late Cretaceous species almost as large if not larger than R. giganticus that shows speciations towards ... Genetic evidence has determined that echidnas diverged from the platypus lineage as recently as 19-48M, when they made their ...
Genetic drift. *Gene flow. *Macroevolution. *Microevolution. *Mutation. *Natural selection. *Speciation. Ecology. *Biodiversity ...
Speciation involves the establishment of genetic barriers between closely related organisms. The extent of genetic ... Molecular keys to speciation: DNA polymorphism and the control of genetic exchange in enterobacteria. Marin Vulić, Francisco ... Molecular keys to speciation: DNA polymorphism and the control of genetic exchange in enterobacteria ... Molecular keys to speciation: DNA polymorphism and the control of genetic exchange in enterobacteria ...
Abstract The review focuses on the genetic consequences of interspecific hybridization and discusses its role in speciation and ... increasing the genetic diversity of plants, including the diversity of... ... Genetic Consequences of Interspecific Hybridization, Its Role in Speciation and Phenotypic Diversity of Plants. ... The review focuses on the genetic consequences of interspecific hybridization and discusses its role in speciation and ...
This project will contribute to answering some of the outstanding questions in speciation with three aims. First, I will ... Speciation in ants: Unraveling the genetic, epigenetic and molecular basis of speciation using wood ants. ... Periodic Reporting for period 1 - SpecIAnt (Speciation in ants: Unraveling the genetic, epigenetic and molecular basis of ... During speciation the genomic architecture of diverging species may diverge to the extent that genes or genomic regions from ...
We used a marker-based approach and a common garden to estimate the additive genetic variation in skeletal traits in a system ... Recent speciation events provide potential opportunities to understand the microevolution of reproductive isolation. ... The quantitative genetics of incipient speciation: heritability and genetic correlations of skeletal traits in populations of ... The patterns of additive genetic variation in this system invite hypotheses of divergent selection or genetic drift as ...
Speciation in Western Scrub-Jays, Haldanes rule, and genetic clines in secondary contact. ... "Speciation in Western Scrub-Jays, Haldanes rule, and genetic clines in secondary contact." Springer Verlag. June 19, 2014. ... Therefore, it is important when studying speciation and species limits in female-heterogametic species like birds to assess the ... Lineage-specific plumage traits were associated with nuclear genetic profiles for individuals in the hybrid zone, indicating ...
This contrasted with the Mendelian character units (genes) which did not usually play a fundamental role in speciation ... associated with hereditary information which was important in speciation. ... Genetic] analysis has revealed hosts of transferable characters [genes]. Their combinations suffice to supply an abundance of [ ... Specific difference [that which is responsible for speciation] therefore must be regarded as probably attached to the base upon ...
... using observations like genetic drift (famously, among the Amish) and the founder effect. The genomics revolution of the ... Genetic Assessment of Squash Genomes in Related Species; The Domestication History of Apples Revealed by Genomic Analysis; ... Genetic Analyses of Sweet Potato Genome Sheds Light on Speciation and Global Dispersion Patterns. By Kevin E. Noonan -- ... Speciation arose from a first autohexaploidy event, with the related species having the following family tree set forth in A:. ...
Publications] Doi,M.: Genetic analysis of Drosophila virilis sex pheromone : genetic mapping of the locus producing Z-(11)- ... Publications] Doi,M: Genetic analysis of Drosophila virilis sex phenomenone:genetic mapping of the locus producing Z-(11)- ... 4)A speciation gene, Lhr of D.simulans was examined whether it rescued hybrids carrying a deficiency of D.melanogaster in the ... Publications] Uenoyama,T.: Genetic studies on premating isolation in Drosophola simulans. I.A D. simulans line highly crossble ...
Population-genetic researches on the speciation and extinction of the freshwater prawn Macrobrachium.. Research Project ... The genetic diversity of population (average heterozygosity) remarkably declined in the medium and large-egg populations in ... Macrobrachium / Speciation / Allozyme analysis / Gene flow / Freshwater prawn / Population-genetics / Parallel evolution / Egg ... Estuarine small-egg populations are considered to maintain genetic circulation over a wide geographic range through the sea ...
explain the role of natural selection and genetic drift in speciation by citing an example zsysttdd -Biology - TopperLearning. ... Explain the role of natural selection and genetic drift in speciation by citing an example. Asked by 1st March 2013, 6:40 PM ... Genetic driftrefers to random changes in gene frequencies that usually occurs in a small population and results from chance ... This is the concept of genetic drift, which provides diversity without any adaptations. ...
Fingerprint Dive into the research topics of Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic ... Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. ...
We study sympatric speciation due to competition in an environment with a broad distribution of resources. We assume that the ... Competitive speciation in quantitative genetic models.. @article{Drossel2000CompetitiveSI, title={Competitive speciation in ... Incipient allochronic speciation due to non-selective assortative mating by flowering time, mutation and genetic drift.. Céline ... Speciation and the evolution of dispersal along environmental gradients. Simone K. Heinz, Rupert Mazzucco, Ulf Dieckmann ...
... populations through selection or genetic drift (reviewed in ref. 1). Although this "allopatric" model of speciation is widely ... Sympatric speciation by allochrony in a seabird. V. L. Friesen, A. L. Smith, E. Gómez-Díaz, M. Bolton, R. W. Furness, J. ... Sympatric speciation by allochrony in a seabird. V. L. Friesen, A. L. Smith, E. Gómez-Díaz, M. Bolton, R. W. Furness, J. ... 2004) in Adaptive Speciation, eds Dieckmann U , Doebeli M , Metz JAJ , Tautz D (Cambridge Univ Press, Cambridge, UK), pp 305- ...
Speciation[edit]. Selfish genetic elements have been shown to play a role in speciation.[40][41][97] This could happen because ... Some selfish genetic elements manipulate the genetic transmission process to their own advantage, and so end up being ... First, sex and outcrossing put selfish genetic elements into new genetic lineages. In contrast, in a highly selfing or asexual ... Selfish genetic elements (historically also referred to as selfish genes, ultra-selfish genes, selfish DNA, parasitic DNA and ...
B. S. Weir, Genetic Data Analysis II: Methods for Discrete Population Genetic Data, Sinauer Associates, Sunderland, Mass, USA, ... Ecological speciation can be defined as a particular type of speciation, where reproductive isolation evolves between ... Figure 2), and the second scenario presents the case where facilitation promotes ecological speciation (. , , , Figure 4). ... The first scenario presents the case where facilitation inhibits ecological speciation (. , , , ...
We further proved the existence of a clear-cut genetic boundary between RKS3044 and the other S. bongori lineages/strains ... Genetic boundaries delineate the potential human pathogen Salmonella bongori into discrete lineages: divergence and speciation ... 2). For example, S. bongori strains RKS3044 and N268-08 had a genetic distance between them similar to that as between S. typhi ... et al. Genetic boundaries delineate the potential human pathogen Salmonella bongori into discrete lineages: divergence and ...
2010). Genetic evidence for hybrid trait speciation in Heliconius butterflies. PLoS Genet 6: e1000930. ... Wang XR, Szmidt AE, Savolainen O . (2001). Genetic composition and diploid hybrid speciation of a high mountain pine, Pinus ... This criterion is based on the argument that the four most compelling cases of hybrid speciation combine genetic evidence of ... Molecular genetic and quantitative trait divergence associated with recent homoploid hybrid speciation: a study of Senecio ...
... genetic coupling) can facilitate speciation [2-4]. Here, we perform a direct test for genetic coupling by mapping both ... Genetic Coupling of Female Mate Choice with Polygenic Ecological Divergence Facilitates Stickleback Speciation.. Publication ... Ecological speciation with gene flow is widespread in nature [1], but it presents a conundrum: how are associations between ... Furthermore, a polygenic genetic model that explains adaptation to contrasting benthic and limnetic feeding niches [5] also ...
... have revealed a strikingly high genetic diversity in the Sebacinales. However, the factors determining this genetic diversity ... By characterising the genetic population structure within these species, we provide insights into species boundaries and the ... In this study, we analysed patterns of genetic variation within two morphological species, Sebacina epigaea and S. incrustans, ... Our results suggest that recombination and negative selection have played significant roles in generating genetic diversity ...
J. Beltman and J. A. Metz, "Speciation: more likely through a genetic or through a learned habitat preference?" Proceedings of ... By any definition, speciation requires genetic divergence. Therefore, integration of ecological developmental biology with the ... S. Via, "Genetic constraints on the evolution of phenotypic plasticity," in Genetic Constraints on Adaptive Evolution, V. ... Whether or not ecological speciation ensues depends on whether genetic reproductive barriers evolve and whether that evolution ...
Ecological speciation can proceed rapidly, but the origin of genetic variation facilitating it has remained elusive. Here, the ... We previously explored the genomics of very recent ecological speciation into lake and stream ecotypes in stickleback from Lake ... Here, we reconstruct the origin of alleles underlying ecological speciation by combining demographic modelling on genome-wide ... Our results highlight an overlooked outcome of secondary contact: ecological speciation facilitated by admixture variation. ...
One lemur, two lemur, three lemur, four: Genetic study reveals the hidden diversity of Madagascars mouse lemurs. ... How do species split? What causes speciation? And what evidence do we have that speciation has ever occurred? Critics of ... While thats clearly a straw man, because most speciation takes far longer than our lifespan to occur, its also not true. We ... from here) One of the models for the evolution of new species is allopatric speciation, where a small isolated population ...
Speciation: Genetic Control (S). To view this video please enable JavaScript, and consider upgrading to a web browser that ... Well, its because theres an underlying genetic basis.. And by knowing the genetic differences between species that are ... speciation is probably not the answer, at least not very common.. Now imagine a situation where the heterozygotes are sterile. ... Speciation and Phylogenetics. This module gets into the nitty gritty of what causes the formation of new species, and how ...
... had a significant historical influence as a tractable system for studying adaptation and is known to play a role in speciation ... Analyses such as these have the potential to uncover the genetic architecture of both within and between species adaptive ... Butterfly speciation and the distribution of gene effect sizes fixed during adaptation Heredity (Edinb). 2009 Jan;102(1):57-65. ... The likelihood of large adaptive peak shifts in mimicry evolution may therefore promote speciation. In addition, mimicry ...
... this comprehensive volume examines patterns of genetic variation within natural insect populations, and explores the underlying ... Sympatric Host-Race Formation and Speciation in Rhagoletis (Diptera: Tephritidae): A Tale of Two Species for Charles D. ... Foundations of Local Adaptation: The Genetic Basis of Host-Plant Use and the Nature of Selection. * Front Matter Pages 89-89 ... Genetic Structure and Local Adaptation in Natural Insect Populations. Effects of Ecology, Life History, and Behavior. ...
Consanguinity, Inbreeding, and Genetic Drift in Italy (MPB-39): Cavalli-Sforza, L.L., Moroni, A. and Zei, G. (Paperback and ... Geographic Variation, Speciation and Clines. (MPB-10), Volume 10: Endler, J.A. (Paperback). ... Genetic Structure and Selection in Subdivided Populations (MPB-40): Rousset, F. (Paperback and eBook). ...
A genetic study of island lizards shows that even those that have been geographically isolated for many millions of years have ... More information: Thorpe RS, Surget-Groba Y, Johansson H (2010) Genetic Tests for Ecological and Allopatric Speciation in ... Ecological speciation by sexual selection on good genes: Is speciation adaptive?. Nov 26, 2009 ... ecological speciation). "The next step is to identify the genes controlling the traits influencing the process of speciation", ...
We study the genetic basis of adaptation in Arabidopsis lyrata and Scots pine (Pinus sylvestris). Some studies have also ... In addition, we are developing basic genetic tools, comparative maps and markers and biological resources for the two species. ... We also examine patterns of incipient speciation in pines, partly in a collaboration with Langzhou University, China. ...
Adaptive norm, genetic load and genetic elite in Drosophila pseudoobscura. Genetics 48: 1467-1485. ... 1989 Two rules of speciation, pp. 180-207 in Speciation and Its Consequences, edited by Otte D., Endler J.. Sinauer Associates ... Dobzhansky used a combination of dominant and recessive genetic markers that would show a hybrids genetic constitution by the ... Is the genetic load in Drosophila pseudoobscura a mutational or a balanced load? Genetics 45: 741-753. ...
THE GENETIC BASIS OF SPECIATION IN DROSOPHILA PSEUDOOBSCURA. Undergraduate Research Journal, [S.l.], june 2017. Available at: , ...
  • The results suggested that the Hmr must have functioned as a suppressor gene other than hybrid lethal suppression in the process of speciation (Watanabe). (
  • Understanding the process of speciation and its constraints requires knowledge on the origin of alleles under ecological, sexual or incompatibility selection. (
  • One of the reasons I've learned to stay away from debates about "what is a species" is that practical species definitions (i.e., something we can use to classify critters) do a lousy job of describing the process of speciation, while conceptually sound species definitions (ones that describe the speciation process) are usually miserable when you actually try to classify organisms. (
  • The next step is to identify the genes controlling the traits influencing the process of speciation", said Roger Thorpe. (
  • Although the fossil record around the times of the key speciation events that splits humans from orangutans, gorillas and chimpanzees is sparse, genetic comparisons of the extant apes enable us to analyse the process of speciation that lead to modern humans. (
  • For Egan and other biologists who specialize in studying the process of speciation, continued " gene flow " between the divergent populations raises significant questions about whether and how R. pomonella may eventually evolve into two species. (
  • The diverse Müllerian mimetic wing patterns of neotropical Heliconius (Nymphalidae) have been proposed to be not only aposematic signals to potential predators, but also intra- and interspecific recognition signals that allow the butterflies to maintain their specific identities, and which perhaps drive the process of speciation, as well. (
  • We study sympatric speciation due to competition in an environment with a broad distribution of resources. (
  • Factors influencing progress toward sympatric speciation. (
  • Emergence and loss of assortative mating in sympatric speciation. (
  • The importance of sympatric speciation (the evolution of reproductive isolation between codistributed populations) in generating biodiversity is highly controversial. (
  • Whereas potential examples of sympatric speciation exist for plants, insects, and fishes, most theoretical models suggest that it requires conditions that are probably not common in nature, and only two possible cases have been described for tetrapods. (
  • This is the first evidence for sympatric speciation by allochrony in a tetrapod, and adds to growing indications that population differentiation and speciation can occur without geographic barriers to gene flow. (
  • Sympatric speciation was first proposed by Darwin but was refuted by Mayr and has been controversial ever since (reviewed in refs. (
  • Although sympatric speciation is possible in theory, most models require conditions that are probably uncommon in nature, such as an appropriate balance between selection and recombination, linkage between genes involved in ecological specialization and reproductive isolation, and/or a small number of loci controlling local adaptation, and habitat and mate preference. (
  • Sympatric speciation is difficult to demonstrate in nature. (
  • Unfortunately, the geographic and phylogenetic signatures of sympatric speciation are easily obscured by range expansion, extinction, and lineage sorting ( 1 , 11 ). (
  • Procellariiformes: Hydrobatidae) provides a useful test model for sympatric speciation. (
  • Now this would be sympatric speciation. (
  • 10. Sympatric Speciation in Herbivorous Insects: Norm or Exception? (
  • Theoretical models show that sympatric speciation can be driven by disruptive selection on resource-use traits combined with assortative mating based on ecological or marker traits [ 12 , 13 ]. (
  • F. J. Sulloway contends that Darwin's position on speciation was "misleading" at the least and may have later misinformed Wagner and David Starr Jordan into believing that Darwin viewed sympatric speciation as the most important mode of speciation. (
  • from here) One of the models for the evolution of new species is allopatric speciation, where a small isolated population diverges from a larger ancestral population. (
  • by allopatric speciation, and others seem to just split off. (
  • Islands epitomize allopatric speciation, where geographic isolation causes individuals of an original species to accumulate sufficient genetic differences to prevent them breeding with each other when they are reunited. (
  • The findings reject allopatric speciation in a case study from a system thought to exemplify it, and suggest the potential importance of speciation due to differences in ecological conditions (ecological speciation). (
  • Thorpe RS, Surget-Groba Y, Johansson H (2010) Genetic Tests for Ecological and Allopatric Speciation in Anoles on an Island Archipelago. (
  • A geographic barrier is the predominant means by which allopatric speciation occurs. (
  • This example of allopatric speciation usually occurs when there are new areas for a species to occupy, after mass extinctions, or when natives have not colonized an area. (
  • This type of allopatric speciation is exemplified in the evolutionary history of honeycreepers. (
  • Fully allopatric speciation can occur across barriers such as the Isthmus of Panama [ 2 ], but these features are not common enough to explain all marine speciation events [ 1 ]. (
  • The polyploid hybrid speciation differs strongly from the classical (among others allopatric) speciation, which usually proceeds over longer evolutionary periods and mostly by spatial separation of populations. (
  • This can happen in a multitude of ways, a common mode of which is known as allopatric speciation. (
  • I leave out discussion of sympatric and allopatric speciation but instead identify the likelihood of ecological and mutation-order speciation when there is gene flow. (
  • this is similar to allopatric speciation in that populations are isolated and prevented from exchanging genes. (
  • This is similar to allopatric speciation but with the distinction that these species stop changing after becoming self sustaining. (
  • Rather, divergence in these fishlineages is consistent with the rarely observedModel III allopatric speciation. (
  • In Species and Speciation in the Fossil Record , experts in the field examine how they conceive of species of fossil animals and consider the implications these different approaches have for thinking about species in the context of macroevolution. (
  • A significant project that will be valuable to working paleontologists and biologists, Species and Speciation in the Fossil Record will serve its purpose nicely. (
  • Endless Forms: Species and Speciation. (
  • In isolated plant populations with various destabilized genomes of hybrid origin under the influence of natural selection and due to genetic drift, gene and chromosomal differences will accumulate, triggering new reproductive isolating mechanisms that increase genetic isolation of a new race or species. (
  • Second, I will investigate the molecular basis of reproductive isolation using protein modeling and network analysis, testing the idea that speciation genes do not evolve independent of each other, but instead are part of same functional networks. (
  • Recent speciation events provide potential opportunities to understand the microevolution of reproductive isolation. (
  • The patterns of additive genetic variation in this system invite hypotheses of divergent selection or genetic drift as potential evolutionary drivers of reproductive isolation. (
  • Speciation-the evolution of reproductive isolation between populations-is thought generally to involve the gradual accumulation of genetic differences between geographically isolated (allopatric) populations through selection or genetic drift (reviewed in ref. 1 ). (
  • 2. The species must have substantial reproductive isolation, preferably based on genetic differences. (
  • Finally, phenotypic plasticity of reproductive characters might directly influence evolution of reproductive isolation (the second component of ecological speciation). (
  • After making explicit my working definitions of key terms, I argue that the "developmental plasticity hypothesis of speciation" [ 13 - 15 ] is a special case of ecological speciation, and I review the subject by breaking down the effects of plasticity on the two components of ecological speciation: adaptive divergence and the evolution of reproductive isolation [ 28 ]. (
  • Dobzhansky's (1936) article in GENETICS represents the first concerted effort to work out the genetic changes producing a puzzling reproductive barrier: hybrid sterility. (
  • A possible explanation is that ecological speciation-reproductive isolation resulting from divergent natural selection between ecological niches-is widespread in marine taxa [ 3 , 4 ]. (
  • Reproductive isolation can arise as a byproduct of ecological divergence, and selection against the production of intermediate phenotypes can favour assortative mating and facilitate speciation. (
  • Ecological differences often evolve early in speciation as divergent natural selection drives adaptation to distinct ecological niches, leading ultimately to reproductive isolation. (
  • We can circumvent this bootless venture by reducing the problem in twain: the generation of genetic variation and its maintenance by reproductive isolation . (
  • However, most people tend rather to associate reproductive isolation with speciation. (
  • Allochronic speciation (also known as allochronic isolation, or temporal isolation) is a form of speciation (specifically ecological speciation) arising from reproductive isolation that occurs due to a change in breeding time that reduces or eliminates gene flow between two populations of a species. (
  • Speciation ultimately results due to the reproductive isolation between two populations. (
  • Allochrony is thought to evolve more easily the greater the heritability of reproductive timing-that is, the greater the link between genes and the timing of reproduction-the more likely speciation will occur. (
  • however genetic factors must be involved for isolation to lead to complete reproductive isolation and subsequent speciation. (
  • The evolutionary process by which new biological species arise (speciation) is a complex process that requires the understanding of many mechanisms such as reproductive isolation, patterns of species diversity, together with the genetic basis underlying the process. (
  • Understanding the mechanisms by which reproductive isolation (breakdown of gene flow between two populations) is achieved, is fundamental for speciation. (
  • Genetic speciation makes references to the group of genes that are involved in maintaining reproductive isolation between species. (
  • Here we review two potential roles of gene expression in ecological speciation: (1) its indirect role in facilitating population persistence and (2) its direct role in contributing to genetically based reproductive isolation. (
  • We also find clear examples of gene expression having effects on phenotypic traits and adaptive genetic divergence, but links to the evolution of reproductive isolation itself remain indirect. (
  • Debate over classification schemes on the mechanisms of speciation and reproductive isolation continue. (
  • Tests of parallel evolution of reproductive isolation, trait-based assortative mating, and reproductive isolation by active selection have demonstrated that ecological speciation is a common means by which new species arise. (
  • Evidence for mutation-order speciation by natural selection is more limited and has been best documented by instances of reproductive isolation resulting from intragenomic conflict. (
  • The effort leading up to this conclusion involved many experimental and conceptual advances, including a revision of the notion of speciation itself, 80 years after publication of On the Origin of the Species , to a definition based on reproductive isolation instead of morphological differences ( 6 , 7 ). (
  • Ecological speciation refers to the evolution of reproductive isolation between populations or subsets of a single population by adaptation to different environments or ecological niches ( 2 , 8 , 9 ). (
  • Following G. S. Mani and B. C. Clarke ( 10 ), I define mutation-order speciation as the evolution of reproductive isolation by the chance occurrence and fixation of different alleles between populations adapting to similar selection pressures. (
  • These genetic patterns are in concordance with the reproductive behavior observations of higher Sonoran male productivity compared with Baja males. (
  • Peripatric speciation states that a population of an ancestral species in a geographically peripheral part of the ancestral range is modified over time until even when the ancestral and daughter populations come into contact, there is reproductive isolation. (
  • Vicariant speciation Speciation by reproductive isolation of populations that are divided by the emergence of an extrinsic barrier, or by the extinction of intervening populations, or by migration into geographically separated regions. (
  • Peripatric speciation (founder effect) Speciation by reproductive isolation of sub-populations peripheral to the main body of a population. (
  • Speciation is thus seen in terms of the evolution of isolating mechanisms and is said to be complete when reproductive barriers are sufficient to prevent gene flow between the two new species . (
  • In this review, we summarize recent work that shows precopulatory male competition can initiate speciation in sympatry, drive divergence of competitive phenotypes in allopatry, and strengthen reproductive barriers between competitive types during secondary contact. (
  • To encourage future research in this area, we place potential mechanisms for speciation by male competition into existing speciation frameworks and propose a theoretical and empirical research agenda to reveal how male competition contributes to the accumulation of reproductive isolation. (
  • More contemporary efforts to understand speciation have expanded earlier conceptions to include a diversity of evolutionary mechanisms explaining genetic divergence and the generation of reproductive isolation (Panhuis et al. (
  • The best-supported mechanism of speciation is ecological speciation, whereby divergent natural selection leads to trait divergence and subsequent reproductive isolation (Nosil 2012). (
  • Speciation - the process by which one species splits into two - involves the evolution of reproductive isolating barriers such as the sterility or inviability of hybrids between populations. (
  • Marker-based estimates of h(2) were comparable to broad-sense heritability (H) obtained from parent-offspring regressions in a common garden for most traits, and similar genetic co-variance matrices for common garden and wild populations may indicate relatively small G × E interactions. (
  • Hiram Bentley Glass and classical geneticists of the Twentieth Century elucidated some of the ways that genetics could inform regarding human populations and their history, using observations like genetic drift (famously, among the Amish) and the 'founder effect. (
  • Estuarine small-egg populations are considered to maintain genetic circulation over a wide geographic range through the sea current (Kuroshio) -mediated larval dispersal. (
  • The genetic diversity of population (average heterozygosity) remarkably declined in the medium and large-egg populations in isolated limnetic systems. (
  • Phenotypic plasticity has often been seen primarily as an alternative to genetic divergence and a feature making populations less responsive to natural selection [ 1 - 3 ]. (
  • Ecological speciation can sometimes rapidly generate reproductively isolated populations coexisting in sympatry, but the origin of genetic variation permitting this is rarely known. (
  • In turn, understanding the origin of alleles requires reconstructing the history of populations undergoing speciation. (
  • Providing an essential foundation for evolutionary theory, this comprehensive volume examines patterns of genetic variation within natural insect populations, and explores the underlying mechanisms that lead to the genetic divergence of coexisting organisms. (
  • In particular, the text investigates current research on finescale genetic structure in natural insect populations. (
  • Part I present case studies of adaptive genetic structure in natural insect populations, including a critical discussion of the strenghts and weaknesses of the experimental methods employed. (
  • Part II addresses the ecological mechanisms that produce adaptive genetic structure in natural insect populations. (
  • This broad-ranging, interdisciplinary source of information supplies a thorough examination of the mechanisms that promote and impede genetic structure in natural insect populations. (
  • While we carefully elucidated the origin of the vast majority of genetic varieties observable today, we didn't quite connect the dots to how these varieties in individuals become distinct populations of new species. (
  • Gene flow, the loss or gain of alleles in a population due to the migration of fertile individuals or between gamete populations, is reduced in all of these speciation modes. (
  • There are two populations that interact by interbreeding, which allows for gene flow (genetic exchange), within a broad geographic range. (
  • If the populations do not recognize each other as potential mates or cannot produce fertile offspring, speciation has occurred because the populations are reproductively isolated. (
  • If speciation has not occurred, the populations can still interbreed successfully to produce viable, fertile offspring. (
  • The idea behind a ring species is that given enough distance and time, populations will diverge in their genetic makeup hindering their ability to interbreed. (
  • The genetic effects of pleistocene ice ages are approached by deduction from paleoenvironmental information, by induction from the genetic structure of populations and species, and by their combination to infer likely consequences. (
  • According to the young-earth model, this rapid speciation was triggered by environmental pressure working on small, isolated populations. (
  • While ecological speciation can occur between strictly allopatric populations, divergent natural selection can also drive speciation in the face of gene flow [ 5 ]. (
  • This is owing to the rather low level of gene flow that is sufficiently capable of homogenising the genetic state of two populations exchanging individuals. (
  • Current approaches to biodiversity conservation are largely based on geographic areas, ecosystems, ecological communities, and species, with less attention on genetic diversity and the evolutionary continuum from populations to species. (
  • Species, in particular, provide a common measure of biodiversity yet in both theory and nature, speciation is typically a protracted process progressing from connected populations to unambiguous species with variable rates of phenotypic, ecological and genetic divergence. (
  • Thus, most recognized species are not genetically uniform and are sometimes highly structured into historically isolated populations worthy of consideration as intraspecific units that represent unique genetic diversity for conservation. (
  • Geographical barriers are often temporary, and their elimination could result in the exchange of genetic variants between populations. (
  • Ecological speciation is the process by which barriers to gene flow between populations evolve due to adaptive divergence via natural selection. (
  • Speciation has largely been divided into discrete modes that correspond to rates of gene flow between two incipient populations. (
  • Under ecological speciation, divergence is driven by divergent natural selection between environments, whereas under mutation-order speciation, divergence occurs when different mutations arise and are fixed in separate populations adapting to similar selection pressures. (
  • Under this view, speciation is defined as the accumulation of sufficiently many differences between populations to warrant their classification as separate taxonomic species. (
  • When independent populations evolve the same characteristics, are the underlying genetic changes similar or different? (
  • To peer into the world of speciation--how one species branches into another--the National Science Foundation (NSF) spoke with George Gilchrist, a program director in the agency's Division of Environmental Biology and with Ken Whitney, a plant biologist at the University of New Mexico who studies populations of experimental sunflowers in Texas. (
  • To get a sense of how quickly the two populations diverged genetically, Egan and colleagues from Notre Dame, the University of Sheffield in Great Britain, the University of Florida and Kansas State University conducted the most extensive genetic analysis of R. pomonella yet undertaken. (
  • The team compiled a database of more than 5 billion nucleotide base pairs to examine the genetic differences between all the populations. (
  • Overall, we found that the genetic changes undergone by this first generation accounted for up to 70 percent of all the genetic changes that had occurred between the two populations since the 1850s. (
  • Kansas State University's Greg Ragland, co-lead author of the study, said, "The changes observed in both experimental and natural populations of R. pomonella underscore the importance of ecological selection at early stages of divergence and call for further integration of studies of speciation and genome divergence. (
  • Peripatric speciation was originally proposed by Ernst Mayr, and is related to the concept of a Founder effect, since small populations often undergo bottlenecks. (
  • However, ecological speciation theory does not fully account for divergence of populations inhabiting similar environments, or divergence in systems in which exaggerated secondary sexual characters are the primary or only traits differing between closely related species, yet both scenarios characterize some particularly speciose animal groups (e.g., birds of paradise, Irestedt et al. (
  • Fisher (1930) provided the first verbal model of speciation by sexual selection via the coevolution of female mating preferences and male secondary sexual traits in divergent populations. (
  • In this paper, we used 21-28 nuclear DNA repeat markers and 10 single copy nuclear genes, to understand the patterns of genetic variation that occur throughout 30 populations of the complex in CAY, the Dominican Republic (DR), JAM and PR. (
  • and (iii) vegetative morphological characters in common to populations on different islands do not conform to genetic relationships. (
  • Is homoploid hybrid speciation that rare? (
  • Homoploid hybrid speciation (HHS) is the formation of a new-hybrid-species, independent from its parents, via hybridization with no whole-genome duplication and thus no increase in ploidy. (
  • Specific implications of natural genetic introgression are addressed with a few examples from butterflies, including transgressive phenotypes and climate-driven homoploid recombinant hybrid speciation. (
  • Some specific examples illustrate these points using the swallowtail butterflies (Papilionidae) with their long-term historical data base (phylogeographical diversity changes) and recent (3-decade) climate-driven temporal and genetic divergence in recombinant homoploid hybrids and relatively recent hybrid speciation of Papilio appalachiensis in North America. (
  • However, recent evidence suggests that interspecific hybridization among Heliconius butterflies may have resulted in adaptive introgression of these very same traits across species boundaries, and in the evolution of new species by homoploid hybrid speciation. (
  • This study reviews recent literature as it bears upon a specific controversy: the hypothesis that one or more Heliconius species in the H. melpomene -silvaniform clade have arisen as the result of homoploid hybrid speciation (HHS). (
  • These three statements, presented as established facts, provide the conceptual framework for the interpretation of new data as further supporting and extending the hybrid speciation hypothesis to additional species such as H. timareta , and perhaps even the silvaniform H. elevatus . (
  • This process, known as Hybrid Speciation, has been documented a number of times in different plants. (
  • Repeated contraction and expansion would accumulate genome differences and adaptations, protected from mixing by hybrid zones, and such a composite mode of speciation could apply to many organisms. (
  • Addressing both the tempo and mode of speciation over time, they show how with careful interpretation and a clear species concept, fossil species may be sufficiently robust for meaningful paleobiological analyses. (
  • Because of this problem, HHS is considered to be an unlikely mode of speciation [ 18 , 19 ], particularly if the hybrid species co-occurs in space, time and ecological requirements with one or both parental taxa: most putative examples in plants and animals involve colonization of novel habitats [ 20 , 21 ]. (
  • That peripatric speciation is by far the most common mode of speciation is indicated not only by the pattern of distribution of incipient recent species but also by the frequency by which new species , apparently having originated somewhere else, suddenly appear in the fossil record. (
  • Helianthus are consistent with an allopatric mode of speciation. (
  • First, I will confirm candidate speciation genes that I have discovered. (
  • Third, I will combine genomic data on three levels to study the relative roles of genes, gene expression and epigenetics in speciation. (
  • During speciation the genomic architecture of diverging species may diverge to the extent that genes or genomic regions from different species become incompatible if brought together in hybrids. (
  • Selfish genetic elements (historically also referred to as selfish genes , ultra-selfish genes , selfish DNA , parasitic DNA and genomic outlaws ) are genetic segments that can enhance their own transmission at the expense of other genes in the genome, even if this has no positive or a net negative effect on organismal fitness. (
  • In using selectively neutral genetic markers, the authors saw that these anoles are freely exchanging genes and therefore not behaving as separate species. (
  • Ecological speciation by sexual selection on good genes: Is speciation adaptive? (
  • Additionally, genes from outside the population can contribute to the genetic variation through the immigration of new individuals. (
  • Over time, if genes are not exchanged, genetic differences arise in each population. (
  • If the speciation happened in the presence of gene flow it might have left signals of which genes first became incompatible and drove the speciation. (
  • An example of the effects of gene expression in two genes (bone morphogenetic protein 4, bmp4, and calmodulin, CaM ) on phenotypic traits of likely importance for ecological speciation in Geospiza , Darwin's finches. (
  • In particular, we are interested in identifying the genes that are important for hybrid dysfunction in evolutionarily young species that are in the process of ongoing speciation, such as the Bogota and USA subspecies of Drosophila pseudoobscura . (
  • Advances in whole genome sequencing and population genetic methods have revealed several surprising classes of genes that evolve rapidly under positive selection. (
  • As a caveat, if genetic information were to be transferred between distantly related forms (those residing in different "boxes"), a purely hierarchical framework would be inadequate to describe the evolution of all genes in a genome. (
  • Therefore, it is important when studying speciation and species limits in female-heterogametic species like birds to assess the signature of gene flow in the nuclear genome as well. (
  • Ecological speciation with gene flow is widespread in nature [1], but it presents a conundrum: how are associations between traits under divergent natural selection and traits that contribute to assortative mating maintained? (
  • Together, these results provide empirical evidence that genetic coupling of assortative mating with traits under divergent ecological selection helps maintain species in the face of gene flow, despite a polygenic basis for adaptation to divergent environments. (
  • Contemporary speciation studies have shown that speciation can sometimes be surprisingly fast even in the face of gene flow, allowing for sympatric divergence or persistence of incipient species. (
  • This dichotomy may be somewhat misleading, however, as empirical work indicates that ecological factors are important in driving speciation regardless of whether or not gene flow is present, leading many to question whether speciation is ever truly nonecological. (
  • Oceans are home to much of the world's biodiversity, but we know little about the processes driving speciation in marine ecosystems with few geographical barriers to gene flow. (
  • Ecological speciation resulting from divergent natural selection between ecological niches can occur in the face of gene flow. (
  • The scarcity of geographical barriers to gene flow in marine ecosystems poses a challenge to the traditional view of speciation, with its emphasis on geographical isolation [ 1 ]. (
  • Ecological speciation with gene flow may involve divergence in two main aspects of the niche, which have been distinguished in studies of trait-based community assembly [ 6 , 7 ]. (
  • In addition to natural selection, allelic frequencies in a population can change over time by mutations, gene flow, and genetic drift. (
  • Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size). (
  • Chromosome rearrangements, such as inversions, can suppress recombination thus contributing to a reduction of gene flow across genomic regions and the accumulation of genetic incompatibilities. (
  • It is still an open question if this speciation was a clean (allopatric) split or if occurred in the presence of gene flow or was followed by admixture events. (
  • The genetic pattern observed of higher variation within Sonora compared to Baja and a unique Y linked haplotype that is absent in Sonora and in relative high frequency within Baja suggest that unidirectional gene flow might occur within the species. (
  • similar to female choice, male competition may be more likely to lead to speciation when working in concert with divergent ecology, and allopatry sets the stage for divergence among environments with reduced gene flow. (
  • We found that each island exhibits a different patterns of genetic variation, gene flow, and migration. (
  • The review focuses on the genetic consequences of interspecific hybridization and discusses its role in speciation and increasing the genetic diversity of plants, including the diversity of species and varieties of cultivated crops and garden plants. (
  • Mimicry has had a significant historical influence as a tractable system for studying adaptation and is known to play a role in speciation. (
  • Did Natural Selection Play a Role in Speciation? (
  • The size and remoteness of a population also play a major role in speciation. (
  • In yeast, DNA sequence divergence inhibits both intra- and interchromosomal recombination in mitosis and meiosis through the activities of MutS and MutL homologs ( 3 - 6 ), implying mechanisms of genetic barriers similar to those studied in bacteria (see also ref. 7 for effects of mouse MutS homolog on mitotic recombination in mice). (
  • Here, we examine how facilitation may interfere with the mechanisms of ecological speciation. (
  • Theoretical models suggest that genetic mechanisms inhibiting free recombination between loci underlying these two types of traits (hereafter, 'genetic coupling') can facilitate speciation [2-4]. (
  • Modeling changes in species breeding patterns due to climate as well as understanding the genetic mechanisms that control it has proven to be important. (
  • In addressing the question of the origin of species, there are two key issues: (1) what are the evolutionary mechanisms of speciation, and (2) what accounts for the separateness and individuality of species in the biota? (
  • Mechanisms of speciation by selection fall into two broad categories: ecological and mutation-order. (
  • I do not differentiate speciation by sexual selection here because natural selection drives the divergence of mate preferences, by either ecological or mutation-order mechanisms, in most theories of the process ( 8 , 11 ). (
  • BIO 538 Molecular Mechanisms of Animal Development (3 SH) An advanced course which examines the molecular and genetic mechanisms underlying cell adhesion, cell-cell communication and signaling pathways, apoptosis, pattern and body axis formation, limb morphogenesis, and sex determination in animals. (
  • Such Dobzhansky-Muller incompatibilities are thought to arise 'incidental' to evolutionary processes, such as genetic drift or directional selection, but a detailed understanding of the ecological and evolutionary mechanisms involved remains elusive. (
  • This module aims to provide insight into modern evolutionary theory, enabling students to evaluate genetic information and biological mechanisms in the context of gene, population, and organism evolution. (
  • For example, segregation distorters are selfish genetic elements that subvert the mechanisms of meiosis to over-represent themselves in gametes, thus gaining a massive evolutionary advantage. (
  • The authors showed that identified genetic loci linked to diabetes can be segregated according to underlying biological mechanisms which can be used to classify individuals, to provide a way forward for individualized diagnosis, monitoring and treatment. (
  • Studies in model organisms where mechanisms of reproduction can be supported by genetic or biochemical evidence are strongly encouraged. (
  • Proposals addressing molecular genetic mechanisms or the structure, maintenance, expression, transfer, and stability of genetic information in DNA, RNA, chromosomes, and proteins and how those processes are regulated and evolve are considered by the Genetic Mechanisms Cluster (Division of Molecular and Cellular Biosciences). (
  • At the same time, phenotypic and genetic diversity of cultivars not only results from the combination of different alleles that already existed in the genomes of the parental species but also is a consequence of the appearance in the first-generation hybrids of new genomic and epigenomic variants that are direct or distant effects of post-hybridization genomic shock, the creative role of which we would like to emphasize. (
  • Therefore, focusing our discussion just on HHS is a simplification if one is interested in understanding the role of hybridization (without polyploidy) in differentiation and speciation. (
  • What role has hybridization played in speciation? (
  • Current projects in the lab include molecular phylogenetic analyses of familial and ordinal level relationships in the arthrodontous mosses, studies of hybridization using molecular and morphological markers, and investigations of cryptic speciation within geographically widespread species. (
  • The combination of two or more genomes of different origin in the first-generation hybrids is usually accompanied by a phenomenon referred to as genomic shock, which results in different genetic and epigenetic changes. (
  • The lack of reduced diversity within genomic islands and of genomic background differentiation led us to hypothesize that ecotypes likely diverged in situ in Lake Constance, either from selection on standing genetic variation or admixture variation. (
  • The elucidation of how recombination is shaping the genomic architecture of organisms and, more in particular, how this affects the speciation process has been a long‐standing question in evolutionary biology. (
  • Population genetics modelling of speciation events informs us of the timing and mode of ancient speciations from present day genomic data. (
  • A strong source of information about speciation is found in the changing gene trees along a genomic alignment. (
  • Hobolth A, Christensen OF, Mailund T and Schierup MH (2007) Genomic relationships and speciation times of human, chimpanzee, and gorilla inferred from a coalescent hidden Markov model. (
  • This results in disruption of the usual epigenetic suppression of TEs, unleashing them to proliferate and spread, which in turn gives rise to novel genetic variation and remodels genomic regulatory circuits, facilitating rapid morphological, ecological and behavioral change, and adaptive radiation. (
  • Today, speciation is one of the most active areas of research in evolutionary biology . (
  • INTRODUCTION Speciation has been a focus in evolutionary biology since the field's inception, dating back to Darwin's On the Origin of Species (1859). (
  • The extent of genetic recombination is a key determinant and a measure of genetic isolation. (
  • The extent of genetic isolation between enterobacteria is a simple mathematical function of DNA sequence divergence. (
  • The inability to undergo genetic recombination with each other isolates related species independently of geographic isolation. (
  • How important is geographical isolation in speciation? (
  • Indeed, there is more genetic isolation between conspecifics from different habitats than between those lizards originating from separate ancient islands. (
  • Sister species in the young and ecologically diverse rockfish genus Sebastes coexist in the northeast Pacific, implying that speciation may not require geographical isolation. (
  • Using the same analysis, I find no support for alternative hypotheses that speciation involves divergence in diet or life history, or that speciation involves geographic isolation by latitude. (
  • As shown below, Muller played a major role in forming the conceptual framework of speciation genetics, including influence in topics such as evolution of hybrid incompatibilities, Haldane's rule, and the possibility of speciation without complete geographical isolation. (
  • The molecular structure of the desat2 gene is apparently related to the degree of sexual isolation in Zimbabwe females 21 , but nothing is known of the sensory signal(s) involved in this case of incipient speciation 22 , 23 . (
  • We used a marker-based approach and a common garden to estimate the additive genetic variation in skeletal traits in a system of two ecomorphs within the coral species Favia fragum: a Tall ecomorph that is a seagrass specialist, and a Short ecomorph that is most abundant on coral reefs. (
  • Lineage-specific plumage traits were associated with nuclear genetic profiles for individuals in the hybrid zone, indicating that these differences are under genetic control. (
  • Here, we perform a direct test for genetic coupling by mapping both divergent traits and female mate choice in a classic model of ecological speciation: sympatric benthic and limnetic threespine stickleback (Gasterosteus aculeatus). (
  • Conversely, since species are defined by their heritable traits, our modern genetic discoveries represent the first real, comprehensive answer to the central question Darwin pursued. (
  • If certain characters diverge during speciation, the amount of evolutionary change in those traits should be proportional to the number of speciation events, not to the amount of time elapsed [ 15 ]. (
  • In a clade in which habitat-first speciation predominates, we can predict that traits associated with the β-niche will show this pattern of 'speciational' change. (
  • Conversely, if within-habitat speciation is common, traits related to the α-niche (e.g. trophic morphology) should exhibit speciational evolution. (
  • These are direct phenotypic benefits, sensory bias, the Fisherian runaway hypothesis, indicator traits and genetic compatibility. (
  • Here we investigate the genetic architecture of niche differentiation in a sympatric species pair of threespine stickleback fish by mapping the environment-dependent effects of phenotypic traits on hybrid feeding and performance under semi-natural conditions. (
  • Moreover, some of the lake-stream divergence in genetic markers was associated within some of the lake-stream divergence in morphological traits. (
  • Adaptive features under differential selection that also serve as cues for assortative mating have been referred to as 'magic traits', which can drive ecological speciation. (
  • The study highlighted the potential role of genetic variants related to the beta cell, pro-insulin, obesity, lipodystrophy and liver/lipid traits in accounting for different patient characteristics, as well as long-term diabetes outcomes. (
  • Proposals addressing the genetic bases of traits, or among-species comparisons of behavioral, physiological or developmental systems, that look at outcomes of evolution alone or in addition to the evolutionary processes that gave rise to those outcomes, are covered by programs in the Division of Integrative Organismal Systems. (
  • Although this "allopatric" model of speciation is widely accepted, it does not provide a satisfactory mechanism for the origin of many species, such as sympatric sister species, and several alternatives have been proposed (reviewed in ref. 1 ). (
  • Controversy exists as to whether Charles Darwin recognized a true geographical-based model of speciation in his publication On the Origin of Species. (
  • Most interestingly, we are engaged in uncovering evidence of genetic conflict involving segregation distorters as a driving force in the evolution of hybrid sterility during the earliest stages of speciation. (
  • Therefore, integration of ecological developmental biology with the well-developed body of fact and theory on the genetics of speciation [ 29 - 31 ] will be more productive than attempting to replace this population genetic foundation. (
  • After this article appeared, however, studies of the genetics of speciation lay fallow for nearly half a century ( Coyne 1985 ). (
  • 1998. The evolutionary genetics of speciation. (
  • Butlin RK and Ritchie MG (2009) Genetics of speciation. (
  • Although neglected by C arlson ( 1981 ) and most other accounts of Muller's contributions, this article represents a foundation for research on the genetics of speciation. (
  • This uncoupling of morphological diversification and speciation in fig-associated nematodes has resulted from a remarkable expansion of discontinuous developmental plasticity. (
  • What processes are involved in diversification and speciation? (
  • Currently available data are consistent with the proposed concept of stress-induced TE mobilization as a trigger of evolutionary diversification and speciation on volcanic islands. (
  • Because these two DNA repair systems are influenced by environmental and physiological factors, and because they control both genetic barriers and the mutation rate ( 8 ), they may be thought of as molecular links between environmental changes and the creation of genetic diversity, influencing directly the rate of bacterial evolution, including pathogenicity ( 9 ) and speciation ( 2 ). (
  • This is the concept of genetic drift, which provides diversity without any adaptations. (
  • Selfish genetic elements have now been described in most groups of organisms, and they demonstrate a remarkable diversity in the ways by which they promote their own transmission. (
  • Cataclysmic Evolution may account for some species but not many, it could only practically apply to asexual species and would undermine genetic diversity. (
  • With large enough population, sufficient genetic diversity is maintained while the gene becomes fixed within a few generations. (
  • This considerable diversity in the absence of geographical barriers has sparked interest in the factors promoting speciation in Sebastes [ 16 , 18 - 20 ]. (
  • Speciation: The process by which biological diversity is generated. (
  • In principle, this flexibility allows for protection of genetic diversity and maintenance of evolutionary processes at a broad range of infra-specific levels. (
  • International conservation policy recognizes biodiversity at three levels, ecosystem, species and genetic, and that management should aim to retain all three ( Convention on Biological Diversity, 2007 ). (
  • This is clearly reflected in the Convention on Biological Diversity, Aichi Biodiversity Targets, agreed in 2010 ( ), where there is specific reference in goals and targets, not only to ecosystems and species, but also to genetic diversity. (
  • Biodiversity across all levels of biological classifications is fundamentally based on genetic diversity. (
  • The genetics of hybrid introgression as a source of novel variation for ecological divergence and evolutionary speciation (and resilience) may generate adaptive potential and diversity fast enough to respond to locally-altered environmental conditions. (
  • The microsatellite loci developed in this study will be useful for studying genetic diversity and speciation events between P. poissonii and closely related Primula species. (
  • Eight of the 11 narrow endemics analyzed had lower levels of genetic diversity than any of their more widespread congeners. (
  • Finally, analyses of haplotype diversity indicate that lineage 1 has experienced a purge of genetic variation that was not observed in the other lineages, suggesting that the three L. monocytogenes lineages may represent distinct species within the framework of the cohesion species concept. (
  • [11] Though long dismissed as genetic curiosities, with little relevance for evolution, they are now recognized to affect a wide swath of biological processes, ranging from genome size and architecture to speciation. (
  • Here, we reconstruct the origin of alleles underlying ecological speciation by combining demographic modelling on genome-wide single nucleotide polymorphisms, phenotypic data and mitochondrial sequence data in the wider European biogeographical context. (
  • We often hear about new 'genome sequences,' commercial kits that can tell you about your ancestry (including pre-human) from your DNA or disease predispositions, debates about the truth of evolution, why animals behave the way they do, and how people found 'genetic evidence for natural selection. (
  • This graph depicts the genome-wide genetic differences that have evolved between a native host race of Rhagoletis pomonella that lays its eggs on hawthorn trees (red) and a new divergent host race (green) that began reproducing on apples trees in the 1850s. (
  • In laboratory experiments, researchers found that raising native haw flies on the apple trees' fruiting cycle for just one generation led to a genome-wide shift (dashed red line) that accounted for up to 70 percent of the genetic differences between the two races. (
  • At the time of the initial experiment, genetic technology only allowed Feder and colleagues to study a handful of changes across the genome. (
  • BIO 535 Advanced Molecular Biology (4 SH) An advanced course which examines the current status of gene cloning and mapping, genome analysis, and human genetic diseases. (
  • In Chapter 4, I attempted to resolve the genetic architecture of host fruit odor discrimination based on a genome wide association (GWA) study. (
  • One version of this idea is formalized in models of parapatric speciation along environmental gradients, caused by divergent natural selection and assortative mating [ 9 ]. (
  • Incipient allochronic speciation due to non-selective assortative mating by flowering time, mutation and genetic drift. (
  • There is a greater chance of a species forming in a small, isolated population because natural selection and genetic drift are more likely to alter the gene pool there. (
  • This change is referred to as genetic drift. (
  • In genetic drift, chance events alter the allele frequencies of a population. (
  • But selection against heterokaryotypes must also have occurred during the initial spread of novel rearrangements within species, suggesting that selection may have been overwhelmed by random genetic drift and/or minimized by homozygosity owing to high rates of inbreeding (e.g. (
  • A consequence of the activity of these two systems is the establishment of a potent genetic barrier through a 10 5 -fold reduction in recombination frequency between the two ≈16% divergent genomes, whereas these two systems have no (MMR) or little (SOS) influence on recombination in isogenic crosses. (
  • in other words, how diverged must two genomes be for an efficient genetic barrier to be established? (
  • Yet, there is much to learn about how natural selection shapes genomes during speciation. (
  • 2) The present day genetic structure of species shows frequent geographic subdivision, with parapatric genomes, hybrid zones and suture zones. (
  • By studying great ape genomes we learn about the speciations along the human lineage, where the human-chimpanzee speciation is of special interest. (
  • Speciation underlies the generation of novel biodiversity. (
  • Although this process is a major generator of biodiversity, its genetic basis is still poorly understood. (
  • A quick guide to genetic and molecular markers used in biodiversity studies. (
  • Is the Subject Area "Cryptic speciation" applicable to this article? (
  • A first step toward answering this question is the revelation of the genetic differences among the S. bongori bacteria isolated from different host species. (
  • For example, those studying adaptation and speciation have often used phrases like "merely plastic" to contrast environmentally induced variation against geographic or species differences with strong genetic bases [ 4 - 8 ]. (
  • Analyses such as these have the potential to uncover the genetic architecture of both within and between species adaptive differences. (
  • We also observed that, when God created the kinds, He frontloaded them with genetic differences-with the potential to form all sorts of new species and varieties. (
  • more specifically, it is the determined genetic basis underlying such differences. (
  • The term allochrony is used to describe the general ecological phenomenon of the differences in phenology that arise between two or more species-speciation caused by allochrony is effectively allochronic speciation. (
  • A single polymorphism Y linked fertility gene exhibit similar genetic patterns of regional differences within the species. (
  • On the role of male competition in speciation: a review and research agenda Tinghitella, Robin M;Lackey, Alycia C R;Martin, Michael;Dijkstra, Peter D;Drury, Jonathan P;Heathcote, Robert;Keagy, Jason;Scordato, Elizabeth S C;Tyers, Alexandra M 2017-12-21 00:00:00 Abstract Support for the role of sexual selection in speciation has grown over the last 30 years. (
  • While that's clearly a straw man, because most speciation takes far longer than our lifespan to occur, it's also not true. (
  • Especially considering the fossil evidence of Punctuated Equilibrium, where these changes have to occur within a few hundred generations, the odds of any speciation is incalculable. (
  • In a biblical model, why does speciation occur? (
  • We also examine patterns of incipient speciation in pines, partly in a collaboration with Langzhou University, China. (
  • For allochronic speciation to be considered to have actually occurred, the model necessitates three major requirements: Phylogenetic analysis must indicate that the two taxa in question are incipient species or clearly sister taxa. (
  • The sensory and genetic bases of incipient speciation between strains of Drosophila melanogaster from Zimbabwe and those from elsewhere are unknown. (
  • Our study represents a step forward in our understanding of the sensory processes involved in this classic case of incipient speciation. (
  • The results reported here reveal that genetic barriers can be established, eliminated, or modified by manipulating two systems which control genetic recombination, SOS and mismatch repair. (
  • A species may be defined as a population of organisms capable of sharing their gene pool through mating and genetic recombination. (
  • The structural basis of the barrier to genetic recombination on the molecular level is the difference in their DNA sequences ( 1 , 2 ). (
  • 8 They say this genetic system would have generated new species rather quickly because the changes occurred through recombination of existing Functional and physical units of heredity passed from parent to offspring. (
  • Speciation involves the establishment of genetic barriers between closely related organisms. (
  • Genetic change in response to natural selection and resulting in organisms with improved performance with respect to some function or feature of the environment. (
  • Speciation in complex organisms isn't the result of a single event, it is the culmination of many changes over, at minimum, hundreds or thousands of generations. (
  • In this way, taxonomy based on shared characteristics could be used as a framework for understanding the evolution of organisms, since it is fundamentally based on the vertical inheritance of genetic information from parent to offspring. (
  • Importantly, the formation of new lineages of organisms can be equated to the formation of two species from a single ancestral stock (speciation). (
  • Here, the authors discuss on the models of chromosomal evolution and the contribution of chromosomal reorganisations in mammalian chromosome evolution, and more specifically, during the human-chimpanzee speciation event. (
  • Genetic Coupling of Female Mate Choice with Polygenic Ecological Divergence Facilitates Stickleback Speciation. (
  • Genetics of ecological divergence during speciation. (
  • Population-genetic researches on the speciation and extinction of the freshwater prawn Macrobrachium. (
  • Genetic driftrefers to random changes in gene frequencies that usually occurs in a small population and results from chance processes alone. (
  • Finally, Part IV combines theoretical and empirical approaches linking genetic structure at the population level with larger-scale patterns of variation, such as host race formation and speciation. (
  • Genetic variation can be generated in a population, for instance, these beetles, simply by random mutations. (
  • Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. (
  • A major disturbance, such as a natural disaster, may drastically reduce population size and thereby diminish genetic variation. (
  • 2012) A fine‐scale chimpanzee genetic map from population sequencing. (
  • Both components might contribute to population persistence, which is required for eventual speciation. (
  • A fundamental principle of diversification is that phenotypic divergence coincides with or follows lineage branching, or speciation ( 3 - 5 ). (
  • This type of genetic variation within a species is called a polymorphism, and "single nucleotide polymorphisms," or SNPs, are the smallest unit of polymorphic variation. (
  • We also tested the hypothesis that levels of genetic polymorphism will be lower in geographically restricted species than in more widespread species. (
  • What is genetic polymorphism? (
  • These findings support the hypothesis that rockfishes undergo ecological speciation on an environmental gradient. (
  • If true, the amount of post-Flood speciation must have been staggering. (
  • As a start, the many ways by which new species might arise by selection can be grouped into two broad categories: ecological speciation and mutation-order speciation. (
  • Part III describes how behavioral and life-history patterns influence genetic structure. (
  • Hobolth A, Dutheil JY, Hawks J, Schierup MH and Mailund T (2011) Incomplete lineage sorting patterns among human, chimpanzee, and orangutan suggest recent orangutan speciation and widespread selection. (
  • The 20th century saw the growth of the field of speciation, with major contributors such as Ernst Mayr researching and documenting species' geographic patterns and relationships. (
  • Contrasting genetic patterns were observed based on microsatellite markers such that no regional split was identified. (
  • In addition, we are developing basic genetic tools, comparative maps and markers and biological resources for the two species. (
  • Mayr maintained that Darwin was unable to address the problem of speciation, as he did not define species using the biological species concept. (
  • From this historical information and the biological and genetic information we have from observing the world today, it is clear that many animals have diversified and speciated since creation and the Flood. (
  • Understand how humans manipulate the transfer of genetic information from one generation to the next and make informed judgements about the social, ethical, and biological implications relating to this manipulation. (
  • Gene duplication and tandem multiplication might alter one family group over time, but doing so in a similar way to many families of the same species so that speciation occurs at the same time to allow for reproduction, the odds are astronomical. (
  • An alternative to habitat-first speciation occurs when disruptive selection favours divergence in the α-niche within a habitat. (
  • Using the biblical history and information from the scientific literature, it appears there is good reason why speciation occurs. (
  • Publications] Doi,M.: 'Genetic analysis of Drosophila virilis sex pheromone : genetic mapping of the locus producing Z-(11)-pentacosene. (
  • In Carlson's detailed biography of Muller, the only mention of Muller's work in speciation is a relatively brief mention of his studies on the genetic basis of sterility in hybrids between Drosophila melanogaster and D. simulans ( C arlson 1981 , pp. 280-281). (
  • The main question today is how does selection lead to speciation? (
  • There are different modes of speciation that can lead to the origin of species. (
  • The pattern of relationships andlevels of anagenetic change observed inindependent lineages for this clade are notconsistent with expectations of the mostcommon modes of speciation, Model I large-scalevicariance or Model II peripheralisolation. (
  • The scientific study of speciation - how species evolve to become new species - began around the time of Charles Darwin in the middle of the 19th century. (
  • The 21st century has seen a resurgence in the study of speciation, with new techniques such as molecular phylogenetics and systematics. (
  • In conclusion, my research advanced the study of speciation in R. pomonella by revealing a potentially key aspect of the neurophysiology contributing to differential host choice. (
  • Recognise and explain the processes driving speciation and how these relate to classification techniques. (
  • Plasticity is an important consideration for studies of speciation in nature, and this topic promises fertile ground for integrating developmental biology with ecology and evolution. (
  • In the 'habitat-first' model, the initial divergence during speciation is between β-niches, with any α-niche divergence coming later [ 8 ]. (
  • The genetic evidence shows that human intervention is not necessary to explain sweet potato presence in Polynesia based on comparisons of the relationship (and divergence) of the Polynesian species ( Ipomoea littoralis Blume) with I. batatas and other New World members of its family. (
  • And what evidence do we have that speciation has ever occurred? (
  • While compelling evidence for 'within-habitat' speciation is rare, it comes from α-niche divergence between young sympatric sister species [ 14 ]. (
  • Speciation, raciation, and colour pattern evolution in Heliconius butterflies: the evidence from hybrid zones. (
  • Alternatively, we present how facilitation may favour colonization of marginal habitats and thus enhance local adaptation and ecological speciation. (
  • Furthermore, a polygenic genetic model that explains adaptation to contrasting benthic and limnetic feeding niches [5] also predicted F2 female mate choice. (
  • These claims are controversial and largely untested, but progress has been made on more modest questions about effects of plasticity on local adaptation (the first component of ecological speciation). (
  • We study the genetic basis of adaptation in Arabidopsis lyrata and Scots pine ( Pinus sylvestris ). (
  • Genetic rescue" via hybrid translocations may provide needed adaptive flexibility for rapid adaptation to environmental change. (
  • Appreciation of the connection between adaptation and speciation began with Darwin when a morphological concept of species largely prevailed. (
  • Is Rapid Speciation Supported? (
  • Young-earth creationists insist the Biblical account of history not only accommodates such rapid speciation but requires it. (
  • 1 Rapid speciation apparently occurred, since early historical records already show a large variety of types similar to those present today. (
  • We previously explored the genomics of very recent ecological speciation into lake and stream ecotypes in stickleback from Lake Constance. (
  • Gene expression during adaptive divergence seems to often involve complex genetic architectures controlled by gene networks, regulatory regions, and "eQTL hotspots. (
  • The severe genetic bottleneck of founder events and effects of inbreeding depression, coupled with the inherently stressful volcanic environment, would seem to predict reduced evolutionary potential and increased risk of extinction, rather than rapid adaptive divergence and speciation. (
  • Mutations, therefore, are critical to the development of diverse life-forms, a phenomenon known as speciation (see Speciation). (
  • The original sources of genetic variation are mutations, which are changes in the nucleotide sequence of DNA. (
  • Mutations create new alleles and increase genetic variability. (
  • Here, I use a novel phylogenetic comparative analysis to show that rockfish speciation is instead associated with divergence in habitat depth and depth-associated morphology, consistent with models of parapatric speciation. (
  • 2014). While the potential for sexual selection alone to drive speciation has been more controversial than the role of natural selection, it has nearly as long a history of study (Ritchie 2007). (
  • Our results highlight an overlooked outcome of secondary contact: ecological speciation facilitated by admixture variation. (