scholarly journals GENE FLOW AND GENETIC DIFFERENTIATION

Genetics ◽  
1974 ◽  
Vol 78 (3) ◽  
pp. 961-965
Author(s):  
P T Spieth
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Population Size ◽  
Local Population ◽  
Biological Significance ◽  
Island Model ◽  
Genetic Identity ◽  
Biological Interpretation ◽  
Different Populations ◽  
Stepping Stone Model

ABSTRACT A brief analysis is presented for the effects of gene flow upon genetic differentiation within and between populations generated by mutation and drift. Previous results obtained with the "island" model are developed into a form that lends itself to biological interpretation. Attention is focused upon the effective local population size and the ratio of the genetic identity of two genes in different populations to that of two genes in the same population. The biological significance of this ratio, which is independent of population size, is discussed. Similarities between the results of this model and those of the "stepping-stone" model are noted.

scholarly journals A cladistic measure of gene flow inferred from the phylogenies of alleles.

Genetics ◽  
1989 ◽  
Vol 123 (3) ◽  
pp. 603-613 ◽  
Author(s):  
M Slatkin ◽  
W P Maddison
Keyword(s):  
Mitochondrial Dna ◽  
Gene Flow ◽  
Migration Rate ◽  
Local Population ◽  
Geographic Location ◽  
Island Model ◽  
Simple Function ◽  
Average Level ◽  
Minimum Number ◽  
Parsimony Criterion

Abstract A method for estimating the average level of gene flow among populations is introduced. The method provides an estimate of Nm, where N is the size of each local population in an island model and m is the migration rate. This method depends on knowing the phylogeny of the nonrecombining segments of DNA that are sampled. Given the phylogeny, the geographic location from which each sample is drawn is treated as multistate character with one state for each geographic location. A parsimony criterion applied to the evolution of this character on the phylogeny provides the minimum number of migration events consistent with the phylogeny. Extensive simulations show that the distribution of this minimum number is a simple function of Nm. Assuming the phylogeny is accurately estimated, this method provides an estimate of Nm that is as nearly as accurate as estimates obtained using FST and other statistics when Nm is moderate. Two examples of the use of this method with mitochondrial DNA data are presented.

scholarly journals Interspecific gene flow and vicariance in Northern African rear-edge white oak populations revealed by joint analysis of microsatellites and flanking sequences.

2021 ◽  
Author(s):  
Lepais Olivier ◽  
Abdeldjalil Aissi ◽  
Errol Véla ◽  
Yassine Beghami
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Population Size ◽  
Evolutionary History ◽  
Evolutionary Significance ◽  
Interspecific Gene Flow ◽  
Continental Scale ◽  
Rear Edge ◽  
Flanking Sequences ◽  
Edge Populations

Rear-edge populations represent reservoirs of potentially unique genetic diversity but are particularly vulnerable to global changes. While continental-scale phylogeographic studies usually do not cover these populations, more focused local scale study of rear-edge populations should help better understand both past evolutionary history and its consequences for the persistence and conservation of these potentially unique populations. We studied molecular variation at 36 sequenced nuclear microsatellites in 11 rear-edge Quercus faginea and Q. canariensis populations across Algeria to shed light on taxonomic relationship, population past evolutionary history and recent demographic trajectory. We used descriptive approach and simulation-based inference to assess the information content and complementarity of linked microsatellite and flanking sequence variations. Genetic differentiation among populations classified into eight well-defined genetic clusters do not allow to unambiguously delineate two species. Instead, continuous level of genetic differentiation indicates interspecific gene flow or drift in isolation. Whereas the analysis of microsatellite variation allowed inferring recent interspecific gene flow, additional nucleotide variation in flanking sequences, by reducing homoplasy, pointed towards ancient interspecific gene flow followed by drift in isolation. The assessment of the weight of each polymorphism in the inference demonstrates the value of linked variation with contrasted mutational mechanisms and rates to refine historical demographic inference. Past population size decline inferred in some of these oak populations as well as low contemporary effective population size for most populations is a concern for the persistence of these populations of high evolutionary significance and conservation value.

scholarly journals Relationship between migration and DNA polymorphism in a local population.

Genetics ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 231-234 ◽  
Author(s):  
F Tajima
Keyword(s):  
Dna Sequences ◽  
Migration Rate ◽  
Dna Polymorphism ◽  
Local Population ◽  
Island Model ◽  
Marginal Populations ◽  
Stepping Stone ◽  
Stepping Stone Model

Abstract The expected amount of DNA polymorphism, measured in terms of the number of nucleotide differences between the two DNA sequences randomly sampled from subpopulations, was studied by using the stepping-stone model and the finite island model, under the assumption that the migration rate is not the same among different subpopulations. The results obtained indicate that the expected amount of DNA polymorphism in the subpopulation with lower migration rate is smaller than that of higher migration rate. This suggests that marginal populations tend to have lower level of DNA polymorphism than central populations if the migration rate in the marginal populations is lower than that of the central populations.

scholarly journals Influence of gene flow and breeding tactics on gene diversity within populations.

Genetics ◽  
1991 ◽  
Vol 129 (2) ◽  
pp. 573-583 ◽  
Author(s):  
R K Chesser
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Population Size ◽  
Effective Population Size ◽  
Gene Diversity ◽  
Island Model ◽  
Effective Population ◽  
Migration Rates ◽  
Asymptotic Values ◽  
Fixation Indices

Abstract Expressions describing the accumulation of gene correlations within and among lineages and individuals of a population are derived. The model permits different migration rates by males and females and accounts for various breeding tactics within lineages. The resultant equations enable calculation of the probabilistic quantities for the fixation indices, rates of loss of genetic variation, accumulation of inbreeding, and coefficients of relationship for the population at any generation. All fixation indices were found to attain asymptotic values rapidly despite the consistent loss of genetic variation and accumulation of inbreeding within the population. The time required to attain asymptotic values, however, was prolonged when gene flow among lineages was relatively low (less than 20%). The degree of genetic differentiation among breeding groups, inbreeding coefficients, and gene correlations within lineages were found to be primarily functions of breeding tactics within groups rather than gene flow among groups. Thus, the asymptotic value of S. Wright's island model is not appropriate for describing genetic differences among groups within populations. An alternative solution is provided that under limited conditions will reduce to the original island model. The evolution of polygynous breeding tactics appears to be more favorable for promoting intragroup gene correlations than modification of migration rates. Inbreeding and variance effective sizes are derived for populations that are structured by different migration and breeding tactics. Processes that reduce the inbreeding effective population size result in a concomitant increase in variance effective population size.

scholarly journals A New Statistic for Detecting Genetic Differentiation

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 2011-2014 ◽  
Author(s):  
Richard R Hudson
Keyword(s):  
Genetic Differentiation ◽  
Dna Sequences ◽  
Genetic Data ◽  
Island Model ◽  
Wide Range ◽  
Infinite Sites Model ◽  
Parameter Values

Abstract A new statistic for detecting genetic differentiation of subpopulations is described. The statistic can be calculated when genetic data are collected on individuals sampled from two or more localities. It is assumed that haplotypic data are obtained, either in the form of DNA sequences or data on many tightly linked markers. Using a symmetric island model, and assuming an infinite-sites model of mutation, it is found that the new statistic is as powerful or more powerful than previously proposed statistics for a wide range of parameter values.

Shallow genetic divergence and distinct phenotypic differences between two Andean hummingbirds: Speciation with gene flow?

The Auk ◽  
2019 ◽  
Vol 136 (4) ◽  
Author(s):  
Catalina Palacios ◽  
Silvana García-R ◽  
Juan Luis Parra ◽  
Andrés M Cuervo ◽  
F Gary Stiles ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Incomplete Lineage Sorting ◽  
Lineage Sorting ◽  
Phenotypic Differences ◽  
Adaptive Mechanisms ◽  
The Face ◽  
Gloger’S Rule ◽  
Divergence With Gene Flow ◽  
Neutral Markers

Abstract Ecological speciation can proceed despite genetic interchange when selection counteracts the homogenizing effects of migration. We tested predictions of this divergence-with-gene-flow model in Coeligena helianthea and C. bonapartei, 2 parapatric Andean hummingbirds with marked plumage divergence. We sequenced putatively neutral markers (mitochondrial DNA [mtDNA] and nuclear ultraconserved elements [UCEs]) to examine genetic structure and gene flow, and a candidate gene (MC1R) to assess its role underlying divergence in coloration. We also tested the prediction of Gloger’s rule that darker forms occur in more humid environments, and examined morphological variation to assess adaptive mechanisms potentially promoting divergence. Genetic differentiation between species was low in both ND2 and UCEs. Coalescent estimates of migration were consistent with divergence with gene flow, but we cannot reject incomplete lineage sorting reflecting recent speciation as an explanation for patterns of genetic variation. MC1R variation was unrelated to phenotypic differences. Species did not differ in macroclimatic niches but were distinct in morphology. Although we reject adaptation to variation in macroclimatic conditions as a cause of divergence, speciation may have occurred in the face of gene flow driven by other ecological pressures or by sexual selection. Marked phenotypic divergence with no neutral genetic differentiation is remarkable for Neotropical birds, and makes C. helianthea and C. bonapartei an appropriate system in which to search for the genetic basis of species differences employing genomics.

The Use of Protein Electrophoresis for Determining Species Boundaries in Amphipods

Crustaceana ◽  
1993 ◽  
Vol 65 (2) ◽  
pp. 265-277 ◽  
Author(s):  
Barbara A. Stewart
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Morphological Variation ◽  
Protein Electrophoresis ◽  
Species Boundaries ◽  
Allopatric Populations ◽  
A Value ◽  
Electrophoretic Data

AbstractThe use of protein electrophoretic data for determining species boundaries in amphipods is addressed. Analysis of published literature on genetic differentiation in amphipods showed that pairs of allopatric populations which have genetic identities (I) above a value of 0.85 probably represent intraspecific populations, whereas pairs of populations which have genetic identities below about 0.45 probably represent different species. It was recommended that if I values fall between 0.45 and 0.85, additional factors such as evidence of a lack of gene flow between the populations, and concordant morphological variation should be considered.

Genetic differentiation and gene flow among six sheep breeds of Mongolian group in China

2008 ◽  
Vol 2 (3) ◽  
pp. 338-342 ◽  
Author(s):  
Yan Geng ◽  
Zhangping Yang ◽  
Hong Chang ◽  
Yongjiang Mao ◽  
Wei Sun ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Sheep Breeds

scholarly journals Dispersal and Differentiation of Deep-Sea Mussels of the GenusBathymodiolus(Mytilidae, Bathymodiolinae)

2009 ◽  
Vol 2009 ◽  
pp. 1-15 ◽  
Author(s):  
Akiko Kyuno ◽  
Mifue Shintaku ◽  
Yuko Fujita ◽  
Hiroto Matsumoto ◽  
Motoo Utsumi ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Shallow Water ◽  
Deep Sea ◽  
Dispersal Ability ◽  
Evolutionary Transition ◽  
Significant Genetic Differentiation ◽  
Evolutionary Processes ◽  
High Dispersal ◽  
High Gene

We sequenced the mitochondrial ND4 gene to elucidate the evolutionary processes ofBathymodiolusmussels and mytilid relatives. Mussels of the subfamily Bathymodiolinae from vents and seeps belonged to 3 groups and mytilid relatives from sunken wood and whale carcasses assumed the outgroup positions to bathymodioline mussels. Shallow water mytilid mussels were positioned more distantly relative to the vent/seep mussels, indicating an evolutionary transition from shallow to deep sea via sunken wood and whale carcasses.Bathymodiolus platifronsis distributed in the seeps and vents, which are approximately 1500 km away. There was no significant genetic differentiation between the populations. There existed high gene flow betweenB. septemdierumandB. breviorand low but not negligible gene flow betweenB. marisindicusandB. septemdierumorB. brevior, although their habitats are 5000–10 000 km away. These indicate a high adaptability to the abyssal environments and a high dispersal ability ofBathymodiolusmussels.

Sign in / Sign up

Export Citation Format

Share Document