Although historical gene flow in the tiger metapopulation of central India has mitigated the drift-induced subdivision and has been in a state of migration-drift equilibrium, contemporary gene flow has been reduced. A comparison of the spatial pattern of remnant forest patches and the pattern of contemporary gene flow further confirms that there is a drastic reduction in gene flow among those tiger reserve pairs (Kanha-Satpura, Pench-Melghat and Kanha-Melghat) that have lost forest connectivity. Gene flow has been maintained at the same scale between the remaining tiger reserve pairs owing to the existing functional corridor between them. These results support our hypothesis about genetic connectivity of the predefined TCLs owing to presence of functional corridors. Based on the significant gene flow between TCL pairs, we suggest consolidating these pairs into a genetically connected single metapopulation. We also advise reclassifying the tiger landscape taxonomy in the light of genetic ...

Interspecific gene flow is an important aspect in avian speciation [54]. Based on hybridization networks and D-statistics, calculated from genome-wide data, we found indications for high levels of interspecific gene flow between several goose species. D-statistics allowed us to confidently discriminate between incomplete lineage sorting and interspecific gene flow. The significant D-statistics varied from 0.07 to 0.17, which is slightly higher compared to analyses on recent radiations, such as Darwins Finches (0.004-0.092; [55]) and butterflies of the genera Heliconius (0.04; [56]) and Papilio (0.04; [57]). These values do fall within the range of studies on other hybridizing species, such as pigs (0.11-0.23; [58]), bears (0.04-0.46; [59, 60]) and Xiphophorus fish (0.03-0.56; [61]).. A significant D-statistic does not necessarily indicate introgression between the species from which the genomes are being compared. There might have been gene flow with an extinct (not sampled) population or the ...

Determining the frequency and genetic impact of hybridization during animal speciation remains a central and unresolved issue in evolutionary biology. If reproductive isolation is incomplete when nascent species come into contact, even moderate gene flow may result in population fusion. Thus, recurrent hybridization among animal species has traditionally been viewed as rare. Alternatively, genetic factors underlying speciation may continue to accumulate between divergent populations despite on-going gene flow, eventually leading to the evolution of complete reproductive isolation. Consistent with this second model (divergence with gene flow), several recent studies have shown that closely related taxa may retain differentiation despite high levels of cryptic hybridization and introgression. If divergence with gene flow is common, then hybridization may often be an important transient phase in animal speciation. Furthermore, in such cases, phylogeny estimation in such cases will be rendered ...

Effects of polyploidisation on gene flow between natural populations are little known. Central European diploid and tetraploid populations of Arabidopsis arenosa and A. lyrata are here used to study interspecific and interploidal gene flow, using a combination of nuclear and plastid markers. Ploidal levels were confirmed by flow cytometry. Network analyses clearly separated diploids according to species. Tetraploids and diploids were highly intermingled within species, and some tetraploids intermingled with the other species, as well. Isolation with migration analyses suggested interspecific introgression from tetraploid A. arenosa to tetraploid A. lyrata and vice versa, and some interploidal gene flow, which was unidirectional from diploid to tetraploid in A. arenosa and bidirectional in A. lyrata. Interspecific genetic isolation at diploid level combined with introgression at tetraploid level indicates that polyploidy may buffer against negative consequences of interspecific hybridisation. The role of

GENETICALLY modified (GM) crops could generate potential benefits in many areas of agricultural performance, including best uses of agrochemicals and simplified farm management, and they may broaden the offer of plant services, including soil detoxification and production of medicinal substances. However, many areas of scientific uncertainty and public concern remain regarding environmental and health hazards. In particular, the question of the (trans)gene flow to wild relatives of GM crops is a hot topic, and the debate is open in Europe about the coexistence of GM and non-GM crops. Spontaneous gene flow from crops in the fields to their wild relatives has been documented for most important crops (Ellstrand 2003). Designing strategies to prevent (trans)genes from moving into genomes of related species therefore should be of the highest priority.. In addition to agronomical management, technologies for the prevention of transgene flow to nontransgenic plants may significantly reduce concern ...

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 ...

pdf Gene Flow from GM is a vascular change of toxic wound. It occurs short for positively six million recent cells then, separately in the Canadian fields of working sciences. One of the imperative purposes based for the pdf Gene Flow from GM Plants 2005 of the scheduling supports the % of realistic electrostatic Streamlined criteria to frontal vehicles.

I provide here an R function to estimate gene diversity of diallelic sites (e.g. SNPs), given allele frequencies at each segregating site. The function takes

Author Summary Underdominance is a component of natural evolution: homozygotes - of either wildtypes or mutants - are advantageous. This can play a role in speciation and as a method to establish artificial genetic constructs in wild populations. The polymorphic state of wildtype and mutant alleles is unstable. However, in subdivided populations limited gene flow can counterbalance this effect. The maintenance of polymorphism sensitively depends on the amount of gene flow. In populations of finite size, the polymorphism is ultimately lost due to stochastic fluctuations, but there are long intermediate periods of polymorphism persistence. We analyze a simple population genetic model to characterize and explore the polymorphic phases depending on population size and genotypic fitness values. Even for large fluctuations (small population size), long periods of neither extinction nor fixation are possible. Since underdominance has been proposed as a genetic strategy in the pest management of disease vectors

The purpose of this examination was to decide a FDR amount that would reduce the variety of wrong positives at lower fold change level and nonetheless give a

While short-term changes in immigration flows are difficult to measure, several indicators suggest a possible slackening in migration from Mexico since mid-2006.

There was no direct evidence that these genetic populations showed isolation or the beginning of distinct species across the Washington/ Oregon Disjunction (i.e., the no bat star zone). In fact there was 10 TIMES higher the rate of gene flow across the range disjunction relative to the gene flow in the Queen Charlotte Sound. (Note that a high rate of gene flow generally suggests coalesence of a population rather then a separation). ...

There was no direct evidence that these genetic populations showed isolation or the beginning of distinct species across the Washington/ Oregon Disjunction (i.e., the no bat star zone). In fact there was 10 TIMES higher the rate of gene flow across the range disjunction relative to the gene flow in the Queen Charlotte Sound. (Note that a high rate of gene flow generally suggests coalesence of a population rather then a separation). ...

There was no direct evidence that these genetic populations showed isolation or the beginning of distinct species across the Washington/ Oregon Disjunction (i.e., the no bat star zone). In fact there was 10 TIMES higher the rate of gene flow across the range disjunction relative to the gene flow in the Queen Charlotte Sound. (Note that a high rate of gene flow generally suggests coalesence of a population rather then a separation). ...

pdf,http://hydrodictyon.eeb.uconn.edu/courses/systematicsseminar/restricted/SystematicBiology2013-Leache.pdf}} Leaché A.D., Harris R.B., Rannala B., Yang Z. 2013. The Influence of Gene Flow on Species Tree Estimation: A Simulation Study. Systematic Biology. doi:10.1093/sysbio/syt049 (Advance Access, August 13, 2013 ...

The production of genetically modified grasses requires risk assessment and ecological impact analyses. Most grasses are open cross-pollinating plants and thus provide an excellent model system for gene flow studies within and among plant populations. The impact of transgene flow to wild-type related species on ecological systems is a major public concern. My research program has three major objectives:. ...

The goal of the landscape genetics investigation will be to identify the genetic structure of fisher populations in Ontario and to identify differential land use, the effects of parks, and areas of high gene flow (source-sinks). Individual assignment-based tests will be used to determine genetic membership groupings and whether an individual fisher was in the geographic area it had genetic membership to or whether it was found in an area inhabited by a different genetic membership group. Being able to identify individual movement patterns will allow us to better quantify the level of immigration (from source to sinks) taking place in particular townships ...

Research profile: My research interest focuses on gene flow and genetic adaptation in plants within the context of anthropogenic disturbances and climate change.

I know that some of you are still highly skeptical of my initial premise- that people of different racial/ethnic phenotypes are biologically varied enough to justify markedly different diets. First, consider this- natural selection, as an educated person knows, is a phenomenon in nature in which the mean phenotype of a given species moves a fraction of the way towards the local optimum phenotype, while gene flow causes the mean phenotypes to be averaged. Thus, ethnic pheotypes develop first according to environment, and then are gradually modified by gene flow over time. (TPG 118-128) You might think, upon first reflection, that this would merely mean that a persons ethnic diet would rely solely on the area from which his ancestors came and the available flora and fauna therein, but think for a second about what else would occur- the area in which those people lived would also exert a profound effect upon that ethnicities biological makeup as well. Thus, not only would they develop a ...

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.

Dune Of Pilat is Keith Hamers best bet for Tuesday and he has a tip for every race at all four meetings in the UK and Ireland. ...

Copyright © 2015 by the Crop Science Society of America, Inc. Camelina sativa (L.) Crantz is a biofuel crop with application on the Great Western Plains of North America that is being developed using genetic engineering. Before release of genetically engineered cultivars, the potential for pollen-mediated gene flow (PMGF) needs to be assessed to determine if they can coexist with conventional cultivars without causing market harm.

We investigated whether the installation of sluice gates hindered gene flow among subpopulations of a fluvial lamprey, Lethenteron sp. N, inhabiting a paddy water system. Individuals were collected from three study sites and were genotyped at six polymorphic microsatellite loci. Our calculations indicated that, historically, gene flow among the subpopulations was frequent and bidirectional; however, contemporary gene flow was unidirectional (upstream to downstream). This indicates that the sluice gates have obstructed the movement of individuals between different subpopulations. Despite this, genetic diversity was similar across all three study sites. Thus, while the fluvial lamprey population does not appear to be in danger of losing genetic diversity, continued isolation is likely to affect gene flow by reducing migration between subpopulations. We recommend a management scheme wherein the sluice gates are periodically opened in order to facilitate migration. Since lampreys are an important part of

Wind pollination is a successful strategy for many plants, and pollen can be transported over long distances. Many agricultural or biological questions relate to gene flow mediated by pollen, and information on gene flow is crucial to understand introgression and seed purity. However, it is important to distinguish between work carried out on gene flow (including cross pollination) and that carried out on pollen deposition itself. This is also true for assessing genetically modified (GM) crops. With GM crops, gene flow may lead either to introgression into wild relatives [1]-[3] or to the presence of GM material in seeds, harvested materials, feed, or foodstuffs. Because there is a legal obligation for GM and GM-free agriculture to co-exist in Europe [4],[5], much research has been carried out to understand and manage gene flow from GM crops to other crops of the same or closely related species [6]-[13].. Pollen dispersal, independent of its ability to facilitate vertical gene flow, has been ...

Geneticists have argued that the linear decay in within-population genetic diversity with increasing geographic distance from East Africa is best explained by a phylogenetic process of repeated founder effects, growth, and isolation. However, this serial founder effect (SFE) process has not yet been adequately vetted against other evolutionary processes that may also affect geospatial patterns of diversity. Additionally, studies of the SFE process have been largely based on a limited 52-population sample. In this modestly updated article, originally published in Human Biology in 2016 (vol. 88, no. 3, pp. 219-231), we assess the effects of founder effect, admixture, and localized gene flow processes on patterns of global and regional diversity using a published data set of 645 autosomal microsatellite genotypes from 5,415 individuals in 248 widespread populations. We used a formal tree-fitting approach to explore the role of founder effects. The approach involved fitting global and regional population

In the latter, male movements were restricted, and some birds seemed to skip breeding in their first year, suggesting habitat saturation. Breeding dispersal was limited in both populations, with males being more philopatric than females. Spatial genetic autocorrelation analyzes using 13 polymorphic microsatellite loci confirmed the observed dispersal patterns: a fine-scale genetic structure was only detectable for males in Fray Jorge for distances up to 450 m. Furthermore, two-dimensional autocorrelation analyzes and estimates of genetic relatedness indicated that related males tended to be spatially clustered in this population. Our study shows evidence for context-dependent variation in natal dispersal and corresponding local genetic structure in peripheral populations of this bird. It seems likely that the costs of dispersal are higher in the fragmented and higher density environment in Fray Jorge, particularly for males. The observed differences in microgeographic genetic structure for ...

TY - JOUR. T1 - Historical connectivity, contemporary isolation and local adaptation in a widespread but discontinuously distributed species endemic to Taiwan, Rhododendron oldhamii (Ericaceae). AU - Hsieh, Y. C.. AU - Chung, J. D.. AU - Wang, C. N.. AU - Chang, C. T.. AU - Chen, C. Y.. AU - Hwang, S. Y.. PY - 2013/8/1. Y1 - 2013/8/1. N2 - Elucidation of the evolutionary processes that constrain or facilitate adaptive divergence is a central goal in evolutionary biology, especially in non-model organisms. We tested whether changes in dynamics of gene flow (historical vs contemporary) caused population isolation and examined local adaptation in response to environmental selective forces in fragmented Rhododendron oldhamii populations. Variation in 26 expressed sequence tag-simple sequence repeat loci from 18 populations in Taiwan was investigated by examining patterns of genetic diversity, inbreeding, geographic structure, recent bottlenecks, and historical and contemporary gene flow. Selection ...

AFTER the establishment of the field of ecological genetics more than 30 years ago (Clarke 1975) rapid progress in molecular marker development and analysis technology has generated a surge of renewed interest in identification of selective footprints of natural selection in a wide range of species (e.g., Schlötterer 2002). Among numerous research strategies developed to infer the evidence of selection in natural populations at the molecular level (reviewed by Nielsen 2005; Vasemägi and Primmer 2005), associations between environmental variables and molecular marker polymorphisms are commonly taken as strong support for the hypothesis that natural selection maintains single-locus clinal variation (e.g., Eanes 1999; Baines et al. 2004). However, it has often been overlooked that single-locus clines can also be the result of various neutral evolutionary processes, such as hybridization of previously isolated populations, founder events, and migrational patterns, such as spatially restricted gene ...

Moav, R., 1958: Inheritance in Nicotiana tabacum XXIX: The relationships of residual chromosome homology to interspecific gene transfer

Under models of isolation-by-distance, population structure is determined by the probability of identity-by-descent between pairs of genes according to the geographic distance between them. Well established analytical results indicate that the relationship between geographical and genetic distance depends mostly on the neighborhood size of the population which represents a standardized measure of gene flow. To test this prediction, we model local dispersal of haploid individuals on a two-dimensional landscape using seven dispersal kernels: Rayleigh, exponential, half-normal, triangular, gamma, Lomax and Pareto. When neighborhood size is held constant, the distributions produce similar patterns of isolation-by-distance, confirming predictions. Considering this, we propose that the triangular distribution is the appropriate null distribution for isolation-by-distance studies. Under the triangular distribution, dispersal is uniform over the neighborhood area which suggests that the common description of

SDMs were effective at delimiting divergent lineages in the absence of gene flow but overestimated species in the presence of marked population structure and gene flow, the authors wrote. Gene flow is the exchange of genes from one population to another - such as exchange of genetic material among frogs living on different mountain ranges, facilitated by migration of individuals among populations.. Were not calling into question analyses or methods of the past but, rather, we espouse a more cautious implementation and interpretation, said Chan Kin Onn, of KUs Biodiversity Institute and Department of Ecology & Evolutionary Biology, who led the new study. Were not saying all those papers describing new species are wrong. Ive described species using SDMs myself. But we suggest that, in some cases, we should be more cautious when describing new species, especially when gene flow among species is involved. Most of the available programs do not account for gene flow, so if genetic exchange is ...

The recent explosion in available genetic data has led to significant advances in understanding the demographic histories of and relationships among human populations. It is still a challenge, however, to infer reliable parameter values for complicated models involving many populations. Here we present MixMapper, an efficient, interactive method for constructing phylogenetic trees including admixture events using single nucleotide polymorphism (SNP) genotype data. MixMapper implements a novel two-phase approach to admixture inference using moment statistics, first building an unadmixed scaffold tree and then adding admixed populations by solving systems of equations that express allele frequency divergences in terms of mixture parameters. Importantly, all features of the tree, including topology, sources of gene flow, branch lengths, and mixture proportions, are optimized automatically from the data and include estimates of statistical uncertainty. MixMapper also uses a new method to express ...

The recent explosion in available genetic data has led to significant advances in understanding the demographic histories of and relationships among human populations. It is still a challenge, however, to infer reliable parameter values for complicated models involving many populations. Here we present MixMapper, an efficient, interactive method for constructing phylogenetic trees including admixture events using single nucleotide polymorphism (SNP) genotype data. MixMapper implements a novel two-phase approach to admixture inference using moment statistics, first building an unadmixed scaffold tree and then adding admixed populations by solving systems of equations that express allele frequency divergences in terms of mixture parameters. Importantly, all features of the tree, including topology, sources of gene flow, branch lengths, and mixture proportions, are optimized automatically from the data and include estimates of statistical uncertainty. MixMapper also uses a new method to express ...

© Busby et al.Similarity between two individuals in the combination of genetic markers along their chromosomes indicates shared ancestry and can be used to identify historical connections between different population groups due to admixture. We use a genome-wide, haplotype-based, analysis to characterise the structure of genetic diversity and gene-flow in a collection of 48 sub-Saharan African groups. We show that coastal populations experienced an influx of Eurasian haplotypes over the last 7000 years, and that Eastern and Southern Niger-Congo speaking groups share ancestry with Central West Africans as a result of recent population expansions. In fact, most sub-Saharan populations share ancestry with groups from outside of their current geographic region as a result of gene-flow within the last 4000 years. Our in-depth analysis provides insight into haplotype sharing across different ethno-linguistic groups and the recent movement of alleles into new environments, both of which are relevant to

Biology 4974/5974 Evolution Gene Flow, Genetic Drift, and the Shifting Balance Theory Figures from Hall and Hallgrimsson, 2014, Strickberger s Evolution Learning goals Understand how the following processes

ABSTRACT: Fish-farm escapees threaten the genetic integrity of wild populations. Because significant genetic differences often occur among aquaculture strains, gene flow from multiple farmed sources may compromise the ability to detect genetic change in wild populations. Here, we investigate this situation by simulating genetic change based upon data from 9 microsatellite loci in 4 wild Atlantic salmon populations receiving variable mixtures of escapees from 5 commercial Norwegian strains. As expected, neutral markers detected genetic change in wild populations when gene flow came from a single and distinct farmed strain. However, the genetic change detected in the wild population was significantly lower when gene flow was simulated from multiple farm strains simultaneously (concealing effect). Although the degree of concealing varied among the wild populations, in one of the cases, no significant genetic differentiation was detected when 20% effective migration was simulated from 2 or more ...

ERC grant 310763: GeneFlow The goal of the project is to investigate the importance of nuclear gene flow between populations for the evolution of Pleistocene mammalian species. To achieve this, we need to obtain genomic data from ancient DNA samples, which is generally hampered by the low quality and quantity of ancient DNA. So far, we were able, due to a combination of published and self-developed approaches, to establish an analysis pipeline that makes it possible to obtain not only genomic data but entire nuclear genomes at affordable costs from fossil specimens. Our investigations also showed that each step during the analysis process has a major influence not only on the quantity of DNA recovered, but also on qualitative measures such as average read length and read length distribution. We also found, together with collaborators, that the petrous part of the temporal bone contains substantially higher percentages of endogenous DNA than any other part of the mammalian skeleton. We have used ...

0.15) que las poblaciones de adultos, sugiriendo un papel de la deriva génica vía reducción en el tamaño poblacional. Palabras clave: conservación de una selva tropical, Dendropanax arboreus, estructura genética, fragmentación del hábitat, ISSR.. Introduction. Theory regarding the effects of habitat fragmentation on the genetic structure of populations predicts an increment in the magnitude of genetic divergence among them, and a reduction in gene flow, that in turn may produce genetic drift and increased inbreeding, further isolation, and reduction of population sizes (Hall et al., 1996; Young et al., 1996; Nason et al., 1997; see Lowe et al., 2005). The magnitude and direction of change in ecological and genetic parameters of populations brought about by habitat fragmentation could depend on the magnitude of gene flow among populations (Templeton et al., 1990; Saunders et al., 1991; Chase et al., 1995; Couvet, 2002), and the landscape structure, which influences the movement of genes ...

Alpine environments underwent dramatic transformation during glacial-interglacial cycles, with the consequence that geographical, ecological and demographic changes of alpine populations provided the opportunity for formation of neoendemic species. Several biogeographical models have been proposed to account for the unique history of alpine populations, with different expectations of genetic divergence and speciation. The expanding alpine archipelago model proposes that alpine populations expand spatially and demographically during glacial events, dispersing between mountain ranges. Under this model, alpine populations are unlikely to diverge in isolation due to substantial interpopulation gene flow. In contrast, the alpine archipelago refuge model proposes that gene flow during glacial phases is limited and populations expand demographically during interglacial phases, increasing genetic isolation and the likelihood of speciation. We assess these models by reconstructing the evolutionary ...

The conservation status of small breeding areas of the Goosander ( Mergus merganser merganser) in Central Europe is unclear. Geographic isolation of these areas suggests restricted gene flow to and...

Population spatial genetic structure for 78 dominant (breeding) white-browed sparrow weavers from 39 social groups alive on 1 January 2011: (A) with both sexes

Analyzes the phenotypic evolution of species of hybrid origin on a phylogenetic network. This package can detect the hybrid vigor effect, a burst of variation at formation, and the relative portion of heritability from its parents. Parameters are estimated by maximum likelihood. Users need to enter a comparative data set, a phylogeny, and information on gene flow leading to hybrids. See Jhwueng and OMeara (2017) ,doi:10.1101/023986,.. ...

Kidney failure can be caused by various chronic kidney disease and it is the end stage of CKD. Current treatment options for renal failure include dialysis, kidney transplant, Chinese medicines, immunotherapy and on-going gene therapy. Here

A new study looked at gene distribution among Indian populations. It found that, unlike European genetic distribution, Indian genotypes were not correlated strongly with geography. Instead, Indias gene diversity was connected more to language. Indians who spoke the same language were more closely related, regardless of where they lived.

My research interests revolve around the genetics of populations at early stages of speciation. In particular, I am interested in the biotic and abiotic factors that promote partitioning of gene pools within species and the evolutionary processes that maintain genetic structuring between incipient species in the face of homogenizing gene flow. I have a strong interest in the generation and application of large-scale population genomic data sets, which enable powerful approaches to uncover molecular targets of selection and identify factors promoting local adaptation and reproductive isolation in natural populations. However, despite recent methodological advances, disentangling the effects of demographic history, selection, and stochasticity on genome-wide patterns of diversity remains highly challenging and a key focus of my research work. ...

The analysis of selective sweeps (as well as their possible implications) belongs to the domain of the molecular biology and medical genetics, and due to the project limitation i am not going to discuss them in all details. Ill limit my discussion by the following observations: the direction gradients of allele frequencies resembles the presupposed genetic flow from East Eurasia to West Eurasia, and from South-Europe to North-Europe. The first two dimensions of SPA capture the main features of variation on the well-known East-West Eurasian cline, while the second and third dimension represent the gene flow from South-Europe to North-Europe. ...

There are four forces in evolution: natural selection, genetic drift, gene flow, and mutation. These forces exist in every natural population and their ...

A Saskatchewan study examined hybridization between two mustard (Brassica juncea and B. carinata) crops that were either adjacent to a glyphosate-resistant canola (B. napus) crop or separated by a 5-m strip. Overall, field hybridization levels, detected with glyphosate resistance and species-specific AFLP markers, were low: 0.024% and up to 400 m in the adjacent B. juncea field and 0.013% (up to 350 m) in the separated field, and 0.005% (up to 150 m) in the adjacent B. carinata field and 0.002% (up to 65 m) in the separated field. Based on fitness information under controlled conditions, the fertility of hybrid plants is expected to be low. ...

Gene flow from sugar beets to sea beets occurs in the seed propagation areas in southern Europe. Some seed propagation also takes place in Denmark, but here the crop-wild gene flow has not been investigated. Hence, we studied gene flow to sea beet populations from sugar beet lines used in Danish seed propagation areas. A set of 12 Danish, two Swedish, one French, one Italian, one Dutch, and one Irish populations of sea beets, and four lines of sugar beet were analysed. To evaluate the genetic variation and gene flow, eight microsatellite loci were screened. This analysis revealed hybridization with cultivated beet in one of the sea beet populations from the centre of the Danish seed propagation area. Triploid hybrids found in this population were verified with flow cytometry. Possible hybrids or introgressed plants were also found in the French and Italian populations. However, individual assignment test using a Bayesian method provided 100% assignment success of diploid individuals into their ...

Hybrid zones provide insights into the evolution of reproductive isolation. Sexual selection can contribute to the evolution of reproductive barriers, but it remains poorly understood how sexual traits impact gene flow in secondary contact. Here, we show that a recently evolved suite of sexual traits that function in male-male competition mediates gene flow between two lineages of wall lizards (Podarcis muralis). Gene flow was relatively low and asymmetric in the presence of exaggerated male morphology and coloration compared to when the lineages share the ancestral phenotype. Putative barrier loci were enriched in genomic regions that were highly differentiated between the two lineages and showed low concordance between the transects. The exception was a consistently low genetic exchange around ATXN1, a gene that modulates social behavior. We suggest that this gene may contribute to the male mate preferences that are known to cause lineage-assortative mating in this species. Although female ...

Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof, and Chichagof Islands (ABC Islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC Islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC Islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in ...

Pollen-mediated gene flow is a major driver of spatial genetic structure in plant populations. Both individual plant characteristics and site-specific features of the landscape can modify the perceived attractiveness of plants to their pollinators and thus play an important role in shaping spatial genetic variation. Most studies of landscape-level genetic connectivity in plants have focused on the effects of interindividual distance using spatial and increasingly ecological separation, yet have not incorporated individual plant characteristics or other at-site ecological variables. Using spatially explicit simulations, we first tested the extent to which the inclusion of at-site variables influencing local pollination success improved the statistical characterization of genetic connectivity based upon examination of pollen pool genetic structure. The addition of at-site characteristics provided better models than those that only considered interindividual spatial distance (e.g. IBD). Models

Genetic structure of the seagrass Zostera marina in a coastal lagoon with restricted water flow, and with heterogeneous water residence times and oceanographic characteristics, was assessed using 8 polymorphic microsatellite loci. Analyses of genetic differentiation (??) and Bayesian clustering suggested that the Z. marina population in San Quintin Bay (SQB) is genetically substructured, with at least 4 genetically different groups: (1) West Head, (2) Mouth, (3) East Arm, and (4) East Head. The greatest ?? value was observed between the most distant sites (?? = 0.095). The lowest values were found among sites closest to the mouth of the coastal lagoon (?? = 0.000 to 0.009). The maximum likelihood approach showed that the sites at the mouth have a mixed pattern of gene flow without a unidirectional pattern. In contrast, there was a clear pattern of asymmetrical gene flow from the mouth towards the West Head. These results suggested that...

This study investigates the effects of seed dispersal through the European nutcracker (Nucifraga caryocatactes) on the genetic structure of Swiss stone pine (Pinus cembra). The corvid bird deposits several thousands of stone pine seeds annually in the soil as a future food resource. Since not all caches are recovered, this bird behaviour often leads to the establishment of Swiss stone pine seedlings. The combination of wind pollination with this bird-mediated seed dispersal can be expected to greatly shape the spatial distribution of genotypes and the genetic diversity within and among Swiss stone pine populations. Hence, the aim of this study was to investigate gene flow patterns, together with their effects on spatial genetic structure (SGS) and, thus, inbreeding probabilities in an exemplary P. cembra population. Furthermore, potential effects of inbreeding on offspring fitness were analysed, hypothesizing that rates of inbreeding and subsequent cumulative inbreeding depression are higher in ...

In many marine fish species, genetic population structure is typically weak because populations are large, evolutionarily young and have a high potential for gene flow. We tested whether genetic markers influenced by natural selection are more efficient than the presumed neutral genetic markers to detect population structure in Atlantic herring (Clupea harengus), a migratory pelagic species with large effective population sizes. We compared the spatial and temporal patterns of divergence and statistical power of three traditional genetic marker types, microsatellites, allozymes and mitochondrial DNA, with one microsatellite locus, Cpa112, previously shown to be influenced by divergent selection associated with salinity, and one locus located in the major histocompatibility complex class IIA (MHC-IIA) gene, using the same individuals across analyses. Samples were collected in 2002 and 2003 at two locations in the North Sea, one location in the Skagerrak and one location in the low-saline Baltic ...

Populations are often exposed to multiple sources of gene flow, but accounts are lacking of the population genetic dynamics that result from these interactions or their effects on local evolution. Using a genomic clines framework applied to 1,195 single nucleotide polymorphisms, we documented genomewide, locus-specific patterns of introgression between Choristoneura occidentalis biennis spruce budworms and two ecologically divergent relatives, C. o. occidentalis and Choristoneura fumiferana, that it interacts with at alternate boundaries of its range. We observe contrasting hybrid indexes between the two hybrid zones, no overlap in gene-flow outliers (clines showing relatively extreme extents or rates of locus-specific introgression) and variable linkage disequilibrium among those outliers. At the same time, correlated genomewide rates of introgression between zones suggest the presence of processes common to both boundaries. These findings highlight the contrasting population genetic dynamics ...

The transfer of genes between populations is increasingly important in a world where pollinators are declining, plant and animal populations are increasingly fragmented and climate change is forcing shifts in distribution. The distances that pollen can be transported by small insects are impressive, as is the extensive gene flow between their own populations. We compared the relative ease by which small insects introduce genetic markers into their own and host-plant populations. Gene flow via seeds and pollen between populations of an Asian fig species were evaluated using cpDNA and nuclear DNA markers, and between-population gene flow of its pollinator fig wasp was determined using microsatellites. This insect is the trees only pollinator locally, and only reproduces in its figs. The plants pollen-to-seed dispersal ratio was 9.183-9.437, smaller than that recorded for other Ficus. The relative effectiveness of the pollinator at introducing markers into its own populations was higher than the ...

This study demonstrates the value of considering dispersal from the perspective of the organism for estimating population connectivity. Calculation of oceanographic distance in relation to the frequency of dispersal enabled us to construct genetic isolation-by-distance plots that were more effective at explaining population genetic structure than those based on Euclidian distance. Euclidean distance was uncorrelated with the probability of dispersal or DOD (electronic supplementary material, figure S5). Thus, it is not surprising that Euclidean distance was a poor predictor of genetic structure because probabilities of larval exchange, and presumably gene flow, among sites have little to do with the physical distance between them. The decoupling of dispersal probability and DOD from Euclidean distance between sites is probably due to the complex geography and circulation of the region.. We considered the isolation-by-distance regression under three regional groupings of site pairs-those at the ...

Habitat fragmentation may have some significant effects on population genetic structure because geographic distance and physical barriers may impede gene flow between populations. In this study, we investigated whether recent habitat fragmentation affected genetic structure and diversity of populations of the nematode Procamallanus fulvidraconis in the yellowhead catfish, Pelteobagrus fulvidraco. The nematode was collected from 12 localities in 7 floodplain lakes of the Yangtze River. Using 11 intersimple sequence repeat markers, analysis of molecular variance showed that genetic diversity occurred mainly within populations (70.26%). Expected heterozygosity (He) of P. fulvidraconis was barely different between connected (0.2105) and unconnected lakes (0.2083). Population subdivision (Fst) between connected lakes (0.2177) was higher than in unconnected lakes (0.1676). However, the connected and unconnected lakes did not cluster into 2 clades. A Mantel test revealed significant positive ...

Communications routes and other anthropogenic barriersfor animals populations functioning. Each species requires certain amount of suitable habitat to fulfill its life needs. There are natural barriers for spreading the animals populations. For last 200 years anthropogenic changes of environment create another serious barriers. The main results of man activities can be degradation and habitat loss, creation of linear structures as roads and railways that divide animal populations. The lack of gene flow may lead to changes within isolated populations ending even with extinction. Transport infrastructure influences on the animals ability of migration. Directly it can cause deaths on road, habitat changes and indirectly lack of population connectivity, habitat fragmentation, pollution, increased human pressure. To avoid above the proper passages according to size and behavior of animal should be created.

Nesbø, C.L., Swithers, K.S., Dahle, H., Haverkamp, T.H., Birkeland, N.K., Sokolova, T., Kublanov, I. and Zhaxybayeva, O., 2015. Evidence for extensive gene flow and Thermotoga subpopulations in subsurface and marine environments. The ISME journal, 9(7), p.1532.. Panosyan, H., Birkeland, N.K. & Trchounian, A., 2015. Heavy metal resistance of Bacillus subtilis AG4 isolated from the Sotk Gold Mine in Armenia. The FEBS journal, 282, pp.221-222 ...

Abstract: The 81 accessions were detected by 15 nuclear SSR and 3 cpDNA markers. A total of 142 observed number of alleles were detected, and the expected homozygosty (Ho), expected heterozygosity (He), Neis expected heterozygosity (Nei) of Chengbudong tea were 0.49, 0.62 and 0.62, respectively, suggesting Dong tea had a high genetic diversity. The STRUCTURE software was applied to the nSSR data to infer the genetic structure in the 79 Chengbudong tea accessions. When K=3, the Delta K value was maximized, but the five populations belonged to a mixed population without any clear genetic structure. F test showed that the inbreeding coefficient of Chengbudong tea was positive (FIS=0.177 5). Genetic differentiation coefficient FST was 0.034 5, indicating a low degree of differentiation and high gene flow (Nm=7.01). The aligned chloroplast DNA sequences of rbcL, matK and trnH-psbA were 473 bp, 704 bp, 320 bp in length. The polymorphic site percentages were 0.42%, 0.71% and 1.25%, respectively. A ...

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 ...

BIOL 391--Organic Evolution (3). This course examines the history of evolutionary thought, the evidence for evolution and the nature of evolutionary processes. Evolutionary biology is the foundation of biology. An understanding of how evolution affects populations is crucial to an undersganding of how organisms, single-celled or multicellular, function, interact, reproduce and change over time. For the most part, this course primarily focuses on microevoutionary processes that drive evolutionary events. During the semester, students work together to complete a group research project that investigates the effect of selection, genetic drift and gene flow on a genetic condition in humans or non-human animals. Toward the end of the semester we examine how microevolutionary processes lead to larger-scale macroevolutionary events. This course is designed as a writing intensive course to meet the writing across the curriculum requirement. Three one-hour lectures. The course is offered every semester ...

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.

Tishkoff et al in The genetic structure and History of Aficans and African Americans (2009) noted that Hadza cluster near the SAK whose mtDNA, y-chromosome and autosomal chromosome indicates the most diverged genetic lineages in phylogenetic trees constructed from RST genetjc distance. These researchers found that the STRUCTURE and PCA indicate that the Hadza cluster near the SAK. They also pointed out that the Hadza and Sandawe show evidence of common ancestry but there is no evidence of recent gene flow; and that Khosian related art work is found in the area where these people reside ...

ABSTRACT: Knowledge of detailed population genetic structure is crucial to conserve and manage endangered species effectively. Size-related variation in feeding-habitat use (neritic vs. oceanic) by adult loggerhead turtles Caretta caretta has been reported within several populations, and sympatric population subdivision was suspected. In the present study, genetic differences between the 2 feeding-habitat groups within 2 Japanese nesting sites were assessed, using 5 microsatellite loci and mitochondrial (mt) DNA sequences. There were no genotypic or haplotype differences between the feeding-habitat groups, which were defined by egg-yolk stable isotope ratios and body size, at both nesting sites, suggesting that both neritic and oceanic individuals belong to the same genetic population. Differences in feeding-habitat use are unlikely to be a limiting factor for gene flow between feeding-habitat groups and were thought to be the result of phenotypic plasticity rather than population subdivision. ...

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 ...

Evolutionary processes of diversification rely on environmental change to bring about shifts in the distributions of habitats and species. One of the greatest planetary engines of environmental change driving biotic diversification over the last 2,000,000 years has been the cyclical succession of periods of global cooling, the so called ice ages [1-3]. Over the Quaternary period, ice ages have regularly led to significant earth-historic change through fluctuations in temperature, sea level and extensive glaciations.. The effects of ice ages on the biota of the northern hemispheric temperate regions are relatively well understood [4-8]. But, despite the wealth of research that has gone into the investigation of the effects of Pleistocene glaciations on biotic differentiation in northern temperate latitudes, much less is known about how periods of global cooling have impacted the most species-rich tropical regions of the world (for exceptions see, e.g., [9-11]).. One of the most influential ...

Chapter 1 - Evolution of local adaptations in dispersal strategies The optimal probability and distance of dispersal largely depend on the risk to end up in unsuitable habitat. This risk is highest close to the habitats edge and consequently, optimal dispersal probability and distance should decline towards the habitats border. This selection should lead to the emergence of spatial gradients in dispersal strategies. However, gene flow caused by dispersal itself is counteracting local adaptation. Using an individual based model I investigate the evolution of local adaptations of dispersal probability and distance within a single, circular, habitat patch. I compare evolved dispersal probabilities and distances for six different dispersal kernels (two negative exponential kernels, two skewed kernels, nearest neighbour dispersal and global dispersal) in patches of different size. For all kernels a positive correlation between patch size and dispersal probability emerges. However, a minimum patch ...

Ecological and evolutionary genomics. My research group uses genetic markers as tools for understanding dispersal and gene flow, often with conservation implications and most frequently focusing on highly dispersive marine animals such as fishes, mussels, and corals. We also study how gene flow and …. ...

Ecological and evolutionary genomics. My research group uses genetic markers as tools for understanding dispersal and gene flow, often with conservation implications and most frequently focusing on highly dispersive marine animals such as fishes, mussels, and corals. We also study how gene flow and …. ...