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: https://doi.org/10.1111/mec.14537. ...
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 ...
Download Aerodyne - Aerosol Chemical Speciation Monitor (ACSM) Brochure. The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) measures quantitative particle ...
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,...
Article Phosphorus Speciation Provides Direction to Produce 10 μg/L. ABSTRACT Increasing demand to achieve very low effluent total phosphorus due to more stringent discharge limits have raised questions on the limits of available technologies a...
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
TY - JOUR. T1 - Investigation of critical equivalence ratio and chemical speciation in flames of ethylbenzene-ethanol blends. AU - Therrien, Richard J.. AU - Ergut, Ali. AU - Levendis, Yiannis. AU - Richter, Henning. AU - Howard, Jack B.. AU - Carlson, Joel B.. PY - 2010. Y1 - 2010. U2 - 10.1016/j.combustflame.2009.07.023. DO - 10.1016/j.combustflame.2009.07.023. M3 - Article. VL - 157. SP - 296. EP - 213. JO - Combustion and Flame. JF - Combustion and Flame. SN - 0010-2180. IS - 2. ER - ...
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.
Welcome to BiologyDiscussion! Our mission is to provide an online platform to help students to share notes in Biology. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. Before sharing your knowledge on this site, please read the following pages:. 1. Content Guidelines ...
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
The v-MFG test: investigating maternal, offspring and maternal-fetal genetic incompatibility effects on disease and viability (pages 333-347). Hsin-Ju Hsieh, Christina G.S. Palmer, Sinead Harney, Julia L. Newton, Paul Wordsworth, Matthew A. Brown and Janet S. Sinsheimer. Version of Record online: 10 APR 2006 , DOI: 10.1002/gepi.20148. ...
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 ...
A total of 12,378 lake whitefish (Coregonus clupeaformis) were tagged at North and Moonlight Bays (NMB) and Peshtigo Reef, Wisconsin, and commercial catches were sampled in 1975 through 1982 to determine vital statistics and fit predictive models for the NMB stock in Green Bay and Lake Michigan. Lake whitefish inhabiting the vicinities of Bark and Cedar Rivers, Chambers Island, Peshtigo Reef, Whitefish Bay and NMB in spring were major components of the NMB spawning stock in fall. Legal whitefish tagged in fall at NMB and sublegal fish tagged in spring at North Bay and Peshtigo Reef moved extensively in the study area. For sublegal whitefish, tag loss was 33% greater than for fish of legal size in the year after tagging. The estimated average annual exploitation rate was 27% in 1976- 1982; it varied with age ranging from 17 to 33% for ages 3 to 12. Ages 4-6 had a greater instantaneous total mortality rate (1.042) than did whitefish of age 3 (0.981) and ages 7-12 (0.420). The instantaneous fishing ...
Adaptive radiation is recognized by a rapid burst of phenotypic, ecological and species diversification. However, it is unknown whether different species within an adaptive radiation evolve reproductive isolation at different rates. We compared patterns of genetic differentiation between nascent species within an adaptive radiation of Cyprinodon pupfishes using genotyping by sequencing. Similar to classic adaptive radiations, this clade exhibits rapid morphological diversification rates and two species are novel trophic specialists, a scale-eater and hard-shelled prey specialist (durophage), yet the radiation is ,10 000 years old. Both specialists and an abundant generalist species all coexist in the benthic zone of lakes on San Salvador Island, Bahamas. Based on 13 912 single-nucleotide polymorphisms (SNPs), we found consistent differences in genetic differentiation between each specialist species and the generalist across seven lakes. The scale-eater showed the greatest genetic differentiation ...
TY - JOUR. T1 - Deviation from the brownian motion expectation implies episodic adaptive divergences in traits of lithocarpus species in Taiwan. AU - Luo, Min Xin. AU - Huang, Meng Yuan. AU - Yang, Chih Kai. AU - He, Yi Zhou. AU - Huang, Bing Hong. AU - Liao, Pei Chun. PY - 2019/6. Y1 - 2019/6. N2 - Adaptive trait divergence is usually episodic rather than universal in a phylogeny. To determine whether trait divergence reaches an extreme level (i.e. deviation from neutrality), the evolutionary rate of the species and intraspecific variation must be taken into account. Accordingly, we attempt to explore the trend of trait divergence over divergence times conditioned on the genetic distance. The Brownian motion (BM) model, a commonly used random-walk process for describing the neutral evolution of traits, is used to simulate the distribution of trait divergence under neutrality. The observed trait divergences are then compared to the BM expectations to detect outliers, which are considered to be ...
Evolutionary changes in traits involved in both ecological divergence and mate choice may produce reproductive isolation and speciation. However, there are few examples of such dual traits, and the genetic and molecular bases of their evolution have not been identified. We show that methyl-branched cuticular hydrocarbons (mbCHCs) are a dual trait that affects both desiccation resistance and mate choice in Drosophila serrata. We identify a fatty acid synthase mFAS (CG3524) responsible for mbCHC production in Drosophila and find that expression of mFAS is undetectable in oenocytes (cells that produce CHCs) of a closely related, desiccation-sensitive species, D. birchii, due in part to multiple changes in cis-regulatory sequences of mFAS. We suggest that ecologically influenced changes in the production of mbCHCs have contributed to reproductive isolation between the two species. ...
HALDANEs rule states that, if species hybrids of one sex only are inviable or sterile, the afflicted sex is much more likely to be heterogametic (XY) than homogametic (XX). We show that most or all of the phenomena associated with HALDANEs rule can be explained by the simple hypothesis that alleles decreasing hybrid fitness are partially recessive. Under this hypothesis, the XY sex suffers more than the XX because X-linked alleles causing postzygotic isolation tend to have greater cumulative effects when hemizygous than when heterozygous, even though the XX sex carries twice as many such alleles. The dominance hypothesis can also account for the large X effect, the disproportionate effect of the X chromosome on hybrid inviability/sterility. In addition, the dominance theory is consistent with: the long temporal lag between the evolution of heterogametic and homogametic postzygotic isolation, the frequency of exceptions to HALDANEs rule, puzzling Drosophila experiments in which unbalanced ...
How species arise is a fundamental and still unanswered question in biology. Under the biological species concept, species consist of populations of interbreeding individuals that are reproductively isolated from other such populations (Mayr 1942). Thus, to understand speciation, we must learn how reproductive barriers evolve between populations. Postzygotic reproductive barriers are commonly found in nature, and occur when hybrid progeny are relatively unfit in comparison to their parents and serve as inefficient bridges for gene flow between populations. Hybrids can be extrinsically unfit, in that they are maladapted to their environment (for example, hybrids exhibit an intermediate phenotype which is unfit in parental environments) or intrinsically unfit, in that they are developmentally abnormal (for example, hybrids are sterile or inviable) (Coyne and Orr 2004).. The Bateson-Dobzhansky-Muller (BDM) model hypothesizes that hybrids are intrinsically unfit due to incompatible gene ...
Fig. 1. Polyploid incidence and speciation frequencies across major groups of vascular plants. Polyploid speciation frequencies are the fractions of branching events that were accompanied by a ploidy shift across the studied phylogenetic trees for each group. The speciation frequencies reported here are based on an irreversible model of polyploid evolution. A binomial standard error follows each incidence and frequency estimate. See Fig. S1 for a diagrammatic explanation of estimation methods for polyploid speciation frequencies. Phylogenetic hypothesis/timescale modified from (13), and based on clades defined in refs. 13-16; clade species richness from refs. 13 and 34. The Higher Monocots are represented by Arecales, Commelinales, Poales, Proteales, Zingiberales; the Basal Monocots by Alistmatales, Asparagales, Dioscoreales, Liliales, Pandanales.. ...
Cryptic sympatric species arise when reproductive isolation is established in sympatry, leading to genetically divergent lineages that are highly similar morphologically or virtually indistinguishable. Although cryptic sympatric species have been reported in various animals, fungi, and protists, there are few compelling examples for plants. This investigation presents a case for cryptic sympatric speciation in Najas flexilis, a widespread aquatic plant, which extends throughout northern North America and Eurasia. The taxon is noted for its variable seed morphology, which earlier research associated with cytotypes; i.e., diploids were characterized by thicker seeds and tetraploids by thinner seeds. However, cytotypes are not patterned geographically with diploid and tetraploid plants often found in close proximity within the same lake. Using digital image and DNA sequence analyses, we found that diploids and tetraploids are well-isolated and remain genetically distinct throughout their sympatric ...
The report Meat Speciation Testing Market by Species (Bos Taurus, Sus Scrofa, Gallus Gallus, Equus Caballus, Ovis Aries), Technology (PCR, ELISA, Molecular Diagnostic), Form (Raw, Cooked, Processed), and Region - Global Forecast to 2022″, The meat speciation testing market is projected to reach USD 2,220.6 Million by 2022, at a CAGR of 8.20% from 2016. The market is driven by increase in number of adulteration and food fraud cases, religious beliefs, compliance with labeling laws, and stringent regulations and consumer demand for certified products.. Browse 82 market data tables and 52 figures spread through 149 pages and in-depth TOC on Meat Speciation Testing Market - Global Forecast to 2022″. Make an Inquiry: http://www.marketsandmarkets.com/Enquiry_Before_Buying.asp?id=245489571. Early buyers will receive 10% customization on this report.. The swine segment, by species, accounted for the largest share in the meat speciation testing market in 2015. The market for swine, among other ...
Evolution, mass extinctions and mass speciations are the result of ionizing radiation, magnetic field reversals, and other factors of an activated planet. The resulting rearrangment of genetic material leads to new species and the extinction of the older species, and this is why mass extinctions are followed by mass speciations.
Hybrid breakdown is a pattern of postzygotic isolation that occurs during the early stages of allopatric divergence, and it is characterized by markedly reduced fitness in F2 and later generation hybrids [1]. Hybrid breakdown has been observed in a wide array of phenotypes, including fecundity [2], sperm swimming speed [3], offspring viability [4,5], growth rate [6] and stress response [7]. The genes involved in the early stages of reproductive isolation are likely to be found in the cellular and biochemical pathways underlying these phenotypes.. Hybrid breakdown is often explained by the Dobzhansky-Muller (DM) model; evolution results in coadaptation among interacting sets of alleles within diverging isolated populations, but incompatibilities are revealed in recombinant F2 genomes of interpopulation hybrids [8,9]. Although most investigations of DM incompatibilities have focused on interactions among nuclear genes [10], epistasis between nuclear and mitochondrial genomes may be particularly ...
Life history traits like developmental time, age and size at maturity are directly related to fitness in all organisms and play a major role in adaptive evolution and speciation processes. Comparative genomic or transcriptomic approaches to identify positively selected genes involved in species divergence can help to generate hypotheses on the driving forces behind speciation. Here we use a bottom-up approach to investigate this hypothesis by comparative analysis of orthologous transcripts of four closely related European Radix species. Snails of the genus Radix occupy species specific distribution ranges with distinct climatic niches, indicating a potential for natural selection driven speciation based on ecological niche differentiation. We then inferred phylogenetic relationships among the four Radix species based on whole mt-genomes plus 23 nuclear loci. Three different tests to infer selection and changes in amino acid properties yielded a total of 134 genes with signatures of positive selection.
The Bateson-Dobzhansky-Muller Model, also known as Dobzhansky-Muller Model, is a model of the evolution of genetic incompatibility, important in understanding the evolution of reproductive isolation during speciation and the role of natural selection in bringing it about. The theory was first described by William Bateson in 1909, then independently described by Theodosius Dobzhansky in 1934, and later elaborated in different forms by Herman Muller, H. Allen Orr and Sergey Gavrilets. The model states that genetic incompatibility is most likely evolved by alternative fixation of two or more loci instead of just one, so that when hybridization occurs, it is the first time for some of the alleles to co-occur in the same individual. For example, imagine two populations that only recently separated geographically. Both sides are starting with the same genotype AABB. One population can then evolve to aaBB, through the transition state AaBB, while the other evolves to AAbb, through the transition state ...
In a matter of months butterflies sporting the yellow and red wing co... We recreated the evolutionary steps that may have given rise to Helic...Sexual encounters between species resulting in hybrid offspring may be...Co-author Mauricio Linares (University of the Andes Colombia) had lon... We found that a wing pattern almost identical to that of the hybrid c...,Butterfly,speciation,event,recreated,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
This BBC video clip introduces 18th century botanist and entrepreneur Thomas Fairchild and his pioneering work into speciation. Use in lessons covering evolution and speciation or as an example of artificial manipulation of life. Could contribute to discussions of genetic modification.
Dieckmann U & Doebeli M (2004). Adaptive dynamics of speciation: Sexual populations. In: Adaptive Speciation. Eds. Dieckmann, U., Doebeli, M., Metz, J.A.J. & Tautz, D., Cambridge: Cambridge University Press. ISBN 0-521-82842-2 DOI:10.2277/0521828422. Full text not available from this repository ...
Application of Model of Plant Population Structure and Phenotypic Divergence - Population structure;Phenotypic divergence;Lotka-Volterra model;Spatial model;
Chromosomal rearrangements, including inversions and translocations, may play dual roles in speciation. First, rearrangements can (and must, in the case of most translocations) cause F1 hybrid sterility, generating costs of heterozygosity that make their spread to define species paradoxical. Second, they suppress recombination in heterozygotes, and thus contribute to the packaging of locally adapted traits and other reproductive barriers in the face of gene flow. Current projects include studies of inversion polymorphism within Mimulus guttatus (e.g. Lee, Fishman et al. 2016) and work on rearrangements and reproductive barriers in the M. cardinalis complex (e.g., Fishman et al. 2013, Stathos & Fishman 2014). ...
An alternative definition offered for anagenesis involves progeny relationships between designated taxa with one or more denominated taxa in line with a branch from the evolutionary tree. Taxa must be within the species or genus and will help identify possible ancestors.[5] When looking at evolutionary descent, there are two mechanisms at play. The first process is when genetic information changes. This means that over time there is enough of a difference in their Genomes and the way that species genes interact with each other during the developmental stage. Anagenesis can be viewed as the processes of sexual and natural selection, and genetic drifts effect on an evolving species over time. The second process, speciation, is closely associated with cladogenesis. Speciation includes the actual separation of lineages, into two or more new species, from one specified species of origin. Cladogenesis can be seen as a similar hypothesis to anagenesis, with the addition of speciation to its ...
In answering these questions, it may be helpful to recognize speciation as one component of a more general process, the evolution of a community. The term community is used in a technical sense by ecologists to summarize information about what species are found in a particular ecological region and about the sizes of the populations of each species. In a particular region, the evolution of a community may involve not only evolutionary change in its component species (usually on a very long time scale), but also changes on a much shorter time scale such as changes in the sizes of the component populations, and addition of new species from outside the region. These more rapid changes are often described by the term ecological succession. Although the time scales are usually quite different, both succession and species evolution may be contributing to the evolution of a community at any point in time. We tend to think of both processes as leading to an equilibrium in which the community is ...
The genetics of adaptation and speciation Adaptation is the most fundamental way that the environment can change the phenotypes of organisms. Adaptations can also lead to the formation of reproductive isolating barriers, which are the building blocks of new species. I am very interested in understanding the genetic underpinnings of reproductive isolation at various stages in the speciation process. Understanding adaptation is also crucial to predicting how organisms will respond to future global change and will help inform management decisions as well as guide future agricultural breeding. Landscape evolutionary genomics One of the core goals of my research program is to understand how the natural landscape molds the genomes of organisms through adaptation. To that end, I am using a combination of genetic mapping and genome sequencing approaches to identify genes involved with adaptation to the heterogeneity of the natural landscape. During my dissertation, I focused on how adaptive alleles in ...
The genetics of adaptation and speciation Adaptation is the most fundamental way that the environment can change the phenotypes of organisms. Adaptations can also lead to the formation of reproductive isolating barriers, which are the building blocks of new species. I am very interested in understanding the genetic underpinnings of reproductive isolation at various stages in the speciation process. Understanding adaptation is also crucial to predicting how organisms will respond to future global change and will help inform management decisions as well as guide future agricultural breeding. Landscape evolutionary genomics One of the core goals of my research program is to understand how the natural landscape molds the genomes of organisms through adaptation. To that end, I am using a combination of genetic mapping and genome sequencing approaches to identify genes involved with adaptation to the heterogeneity of the natural landscape. During my dissertation, I focused on how adaptive alleles in ...
An Annotated Journey through Modern Visual Neuroscience 1/2/20. What remains is to determine, on single trials, exactly how many cells and of which type and in which brain region are responsible for specific forms of perception, and to what extent such computations are distributed across different levels of the visual hierarchy.. See for comparison: Evolutionists Cannot Account for the Origin of the Sense of Smell. Try to move forward without learning anything about how the light-activated assembly of the microRNA-RNA-peptide nanocomplex links the Creation of ATP and the Creation of RNA to biophysically constrained viral latency and healthy longevity via the focus on Hippocampal Place Cells or any other obfuscation of established cause and effect.. See: Five Decades of Hippocampal Place Cells and EEG Rhythms in Behaving Rats. How hippocampal computations affect downstream structures to facilitate memory-guided behaviors remains more of a mystery.. See for comparison: Scent of Eros: Mysteries of ...
An overview of organismal diversity and evolution. Through a taxonomic survey, students are introduced to prokaryotic and eukaryotic diversity and evolution including microorganisms, fungi, plants, and animals. Fundamentals of evolution including the history of life, evidence for common ancestry, mechanisms of evolutionary change, and speciation are covered. Organismic structure, function, and ecology are also explored. Laboratories introduce students to the process and methods of science through investigative experiences. This course is designed for the science major. A year of high school biology and a year of high school chemistry are highly recommended. Additional course fee applies. Prerequisites: University Entry-Level Expectations met for mathematics and English. ...
Genome-Wide Scan for Adaptive Divergence and Association with Population-Specific Covariates mathieu gautier doi: http://dx.doi.org/10.1101/023721 In population genomics studies, accounting for the neutral covariance structure across population allele frequencies is critical to improve the robustness of genome-wide scan approaches. Elaborating on the BayEnv model, this study investigates several modeling extensions i) to improve the estimation accuracy…
A species is a group of organisms that can reproduce to create fertile offspring.. The Process of Geographical Speciation:. 1. A species becomes isolated e.g. because of floods, volcanic activity etc.. 2. A barrier is formed between the two populations so they cant meet to breed.. 3. There is a genetic variation between…. ...
Buy Shrews, Chromosomes and Speciation (9781107011373): NHBS - Jeremy B Searle, P David Polly, Jan Zima, Cambridge University Press
Computational Techniques for Biologic Species Distribution Modeling: 10.4018/978-1-61692-871-1.ch015: Computational modeling techniques for species geographic distribution are critical to support the task of identifying areas with high risk of loss of
The economic numbers just continue to get worse and worse, and at this point it has become exceedingly clear that an economic slowdown is happening. In fact, even the chair of the Federal Reserve is using the term slowdown to describe what is taking place. But of course many are still hoping that the U.S. economy can pull out of this slump and avoid the sort of crippling recession that we experienced in 2008. Unfortunately, that may be really tough because the entire global economy is slowing down right now. Our world is more interconnected than ever before, and what happens on one side of the planet is invariably going to affect the other side of the planet. Some parts of the globe are already mired in deep economic problems, and the U.S. appears to be following down the same path.. If you still think that the economy is in good shape, please read over the following list very carefully.. The following are 14 very alarming numbers that reveal the true state of the economy…. #1 Continuing ...
You might wonder why birds like Macgregoria and the melampittas were included within Paradisaeidae when modern studies have found them to be nothing of the sort. Remember that many species are simply placed in a given taxonomic group because, historically, it has seemed about right, not because specific, detailed analysis has confirmed the close alliance of the species concerned with the undoubted core members of the group in question. Ive covered this sort of thing a few times before (go here and here for discussions of this phenomenon as seen in colubrid snakes).. It goes without saying that the approximately 40 bird-of-paradise species are a fascinating lot and Im not about to do justice to them here. Theyre remarkable not only for the flamboyant display plumage and massive sexual dimorphism present in many (though not all) species, but also for their incredible vocal displays and feeding specialisations. Theyre very obviously core corvoids, close to such groups as cuckoo-shrikes, ...
The application of phylogenetic and genomic analyses to the study of animal biodiversity and evolution, with a specific focus on mammals, is the main goal of the Phylogeny and Phylogeography of Mammals lab. Using next-generation sequencing techniques and advanced bioinformatics tools, the population divergence and speciation process in different species complexes are analysed in order to obtain a better description of our biological diversity. These modern methodologies are also used to study kinship relationships and connectivity between populations in some species of great conservation importance, such as the Pyrenean desman.. Lab website: Castresana Lab. ...
Summary[edit] DescriptionAPI English: Paradise Riflebird (Ptiloris paradiseus) Maleny, SE Queensland, Australia Date September 1995 Source Own work Author Aviceda Camera location 26° 46⠲ 45⠳ S, 152° 52⠲ 54.4⠳ E View all coordinates using: OpenStreetMap - Google Earth -26.779167; 152.881778 ...
Dinis MT, Ribeiro L, Conceição LEC, Aragão C. Larvae digestion and new weaning experiments in Solea senegalensis. In: Recent Advances In Mediterranean Aquaculture Finfish Species Diversification. Vol. 47. Recent advances in Mediterranean aquaculture finfish species diversification. Zaragoza : CIHEAM; 2000:193-204. http://om.ciheam.org/om/pdf/c47/00600619.pdf. ...
Reproductive barriers exist between the house mouse subspecies, Mus musculus musculus and M. m. domesticus, members of the Mus musculus species complex, primarily as a result of hybrid male infertilit
A third, and for now final, problem with reproductive barriers is that they are not, as Agar notes, all-or-none affairs. He cites the example of the New Zealand bird the black stilt which has been breeding itself to death by mating with the Australian pied stilt. The fact that such interbreeding occurs may suggest that they are not truly distinct species, but Agar argues that the situation is more complex than that. There is still some degree of reproductive isolation between the populations: pied stilts prefer to mate with other pied stilts; and black stilts prefer to mater with other black stilts. It is only when their preferred mating partners are absent that they mate with one another. Given this situation, it might be possible for full reproductive isolation to be reinstalled or for the reproductive barriers to break down completely ...
Given enough time, the genetic and phenotypic divergence between populations will affect characters that influence reproduction: if individuals of the two
I got this guy back in mid May at Petsmart, I could see when I bought him that he was going to develop into a cool looking fish, here are a couple of pics. The first one is from mid-May, hes the white/pink one in the bottom righthand corner. Then the second pic is him to date. Sorry for the bad pics, I took them with my phone. Will update better pics soon. Let me know whatcha think ...
Asian currencies found support on Wednesday from a slowdown in the spread of coronavirus, but a strong dollar and caution about the rising death toll kept gains in check, while the New Zealand dollar jumped after the central bank dropped its easing bias.
Excuse the blog slowdown over the next week or so. Weve taken the big jump back to South Africa, and we dont have internet set up (not to mention we dont have a couch, a table etc etc). Not to worry Im thinking of some kickass content to share with you.
The effects of economic slowdown across various segments of the consumption economy that had a major impact on credit growth in domestic banks is gradually fading as consumers are back to spending with the arrival of festival season, said State Bank of India chairman Rajnish Kumar.
U.S. President Obama said his priority was averting an economic slowdown, not balancing the budget in 10 years, House Republicans said after meeting with him.
|b|Economics in a nutshell:|/b| The current economic slowdown, that hopefully can be blamed on the weather, is widespread. - Joel L. Naroff, Philadelphia Philly.com
I ask asked this question on other forums and find a little help. But i figure if there is any place to to ask this question this is the place ...
This paper revisits the Home Bias Puzzle -- the relatively low interna- tional diversification of portfolios. We suggest that part of the diversifi- cation puzzle may be due to reliance on the conventional CAPM model as the benchmark predicting patterns of diversification. We compare the asset diver- sification patterns of agents who maximize a generalized expected utility (GEU) to the diversification of agents who maximize the conventional expected utility (EU). Specifically, we derive the patterns of diversification for agents who maximize a rank-dependent expected utility, attaching more weight to bad than to good outcomes, in contrast to the probability weights used in a conventional expected utility maximization. We show that agents who maximize a GEU exhibit first order risk aversion and tend to refrain from di- versification in contrast to the diversification of agents who maximize the EU. For a given covariance structure we identify a `cone of diversifica- tion -- the range of ...
Every individual alive today, the highest as well as the lowest, is derived in an unbroken line from the first and lowest forms - August Frederick Lopold Weismann, German biologist/geneticist (1834-1914 ...