scholarly journals GENETIC DRIFT AND GENE FLOW IN POPULATIONS OF THE GREAT GERBILS

2018 ◽  
Vol 3 (4) ◽  
pp. 147-151
Author(s):  
V. V. Sutyagin
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Drift ◽  
Small Groups ◽  
Stochastic Matrix ◽  
Large Population ◽  
Random Fluctuation ◽  
Gene Frequencies ◽  
The Family ◽  
Different Populations

The article describes the additional evolutionary factors, apart from natural selection, which can influence the genetic structure of the  populations of the main carriers of the plague microbe – the great  gerbil. The influence of genetic drift on random fluctuation of alleles  is considered. With the help of a stochastic matrix, on the example  of the family group of gerbils consisting of four individuals, the  probabilities of the transition of allele frequencies from parents to  offspring are calculated. Based on the previously calculated size of  the neighborhood in gerbils, it is concluded that any large population  of great gerbils can be considered as small in terms of deviation of gene frequencies. In such small groups – parcels –  the drift of genes will be of great importance. In addition, the effect  of the gene flow on the genetic structure of the gerbil population on  the example of the simplest population model “continent-island” is  considered. The dynamics of changes in allelic frequencies for 100  generations has been calculated. It is shown that the allele  frequency during the 20-30 generations changes at the maximum  rate, and then slows as the equilibrium is approached. It is  concluded that different populations of gerbils should be considered  as separate historically formed structures, with different sequence of influence of external environmental factors on them.

scholarly journals Uncorrelated genetic drift of gene frequencies and linkage disequilibrium in some models of linked overdominant polymorphisms

1974 ◽  
Vol 24 (3) ◽  
pp. 281-294 ◽  
Author(s):  
Joseph Felsenstein
Keyword(s):  
Linkage Disequilibrium ◽  
Covariance Matrix ◽  
Genetic Drift ◽  
Conditional Distribution ◽  
Large Population ◽  
Multivariate Normal ◽  
Gene Frequencies ◽  
Constant Variance ◽  
Population Sizes ◽  
Multiplicative Family

SUMMARYFor large population sizes, gene frequencies p and q at two linked over-dominant loci and the linkage disequilibrium parameter D will remain close to their equilibrium values. We can treat selection and recombination as approximately linear forces on p, q and D, and we can treat genetic drift as a multivariate normal perturbation with constant variance-covariance matrix. For the additive-multiplicative family of two-locus models, p, q and D are shown to be (approximately) uncorrelated. Expressions for their variances are obtained. When selection coefficients are small the variances of p and q are those previously given by Robertson for a single locus. For small recombination fractions the variance of D is that obtained for neutral loci by Ohta & Kimura. For larger recombination fractions the result differs from theirs, so that for unlinked loci r2 ≃ 2/(3N) instead of 1/(2N). For the Lewontin-Kojima and Bodmer symmetric viability models, and for a model symmetric at only one of the loci, a more exact argument is possible. In the asymptotic conditional distribution in these cases, various of p, q and D are uncorrelated, depending on the type of symmetiy in the model.

scholarly journals Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 2. Separating the relative effects of gene flow and genetic drift

2016 ◽  
Vol 9 (8) ◽  
pp. 1005-1016 ◽  
Author(s):  
Cécile Gracianne ◽  
Pierre-Loup Jan ◽  
Sylvain Fournet ◽  
Eric Olivier ◽  
Jean-François Arnaud ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Drift ◽  
Temporal Sampling ◽  
Naturally Occurring ◽  
Phytoparasitic Nematode

scholarly journals The genetic structure of populations of orchids and its evolutionary importance: understanding processes from patterns

Lankesteriana ◽  
2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Raymond L. Tremblay
Keyword(s):  
Gene Flow ◽  
Natural Selection ◽  
Genetic Structure ◽  
Population Size ◽  
Effective Population Size ◽  
Genetic Drift ◽  
Mating Systems ◽  
Mutation Rates ◽  
Effective Population ◽  
Genetic Structure Of Populations

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>Evolution through either natural selection or genetic drift is dependent on variation at the genetic and mor- phological levels. Processes that influence the genetic structure of populations include mating systems, effective population size, mutation rates and gene flow among populations. </span></p></div></div></div>

scholarly journals Genetic Structure and Gene Flow of Octopus maya (Mollusca: Cephalopoda) in the States of Yucatan and Campeche, Mexico / Estrutura genética e fluxo gênico do polvo maya (Mollusca: Cephalopoda) nos Estados de Yucatan e Campeche, México

2021 ◽  
Vol 4 (3) ◽  
pp. 3355-3367
Author(s):  
Jorge Arturo Tello Cetina ◽  
Mariel Sinai Garrido Balam ◽  
Flavia Jovita Cruz Pérez ◽  
Nidia Isabel Jiménez Suaste ◽  
Luis Joaquín Alberto Mota Pino ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Population Genetic ◽  
Marine Invertebrate ◽  
Yucatan Peninsula ◽  
Genetic Distances ◽  
Process Data ◽  
Gene Frequencies ◽  
Yucatán Peninsula ◽  
Octopus Maya

It was determined the population genetic structure of the red octopus Octopus maya in the states of Campeche and Yucatan in Yucatan Peninsula, Mexico, through the expression of isozymes in polyacrylamide gels. Mantle samples from 25 octopuses, captured in nine sites of the Yucatan Peninsula, were used to characterize the genotypic expression revealed by the expression of 26 loci in thirty enzyme systems. Program TFPGA version 1.3 (Tools for Population Genetic Analyses), was used to process data of allozyme gene frequencies of the studied populations. The parameters determined were: descriptive statistics, F statistics, genetic distances, Hardy - Weinberg, UPGMA and the number of migrants as an indicator of gene flow. The average number of alleles per locus, percentage of polymorphic loci, average and direct and direct heterozygosity were: 1.08 ± 0.05 to 1.15 ± 0.04. P95 26.9231% to 34.6154, Have 0.1142 to 0.1390 and Hdir = 0.0354 to 0.0938 respectively. Heterozygosity values in a range of 0.3506 to 0.4793 and G6PDH for ARGK with an average heterozygosity value of 0.1824, Fisher average value of 0.5313 and 0.0140 Fst indicates a heterozygous deficiency but it is within the ranges reported for marine invertebrate species. The number of migrants derived from the Slatkin equation is 1824 per generation, globally indicates some degree of variability between sites and is consistent with the low values of Nei genetic distance found, particularly the node showing the separation of the population of Lagartos River and Dzilam Bravo from the other locations with an obtained value of 0.0004. From the results of this study, it is concluded that locations of Octopus maya have a certain level of interpopulation genetic variability that does not reflect its fragility.

scholarly journals An investigation on the chloroplast and nuclear genomes of taxa belong to the subgenus Dracunculus (Bess.) Rydb. of Artemisia L. (Asteraceae) in Turkey

2022 ◽  
Vol 82 ◽  
Author(s):  
P. YILMAZ SANCAR ◽  
C. F. WAHI D ◽  
S. CIVELEK ◽  
M. KURSAT
Keyword(s):  
Gene Flow ◽  
Chloroplast Dna ◽  
Nuclear Dna ◽  
Molecular Study ◽  
Species Level ◽  
Accession Number ◽  
Natural Classification ◽  
The Family ◽  
Different Populations ◽  
Nuclear Genomes

Abstract Artemisia is one of the biggest genera in the family Asteraceae, with around 500-600 taxa at specific and sub-specific levels and organised in 5 subgenera. Due to the high number of taxa, a lot taxonomists are trying to solve the problem of its classification and phylogeny but its natural classification still hasn’t been achieved. In this research, 60 individuals belonging to 4 taxa of the subgenus Dracunculus of Artemisia L. in Turkey were examined. For all the examined individuals from both the same and different populations belonging to the taxa of the subgenus Dracunculus, the sequences of the regions both psbA-trnH of chloroplast DNA and ITS of nuclear DNA were determined. Also, the gene regions obtained were recorded in the NCBI GenBank database and an accession number was taken. It was found that there was no gene flow and hybridization between the four studied taxa of the subgenus Dracunculus, and these 4 taxa also completed their speciation. According to the results of this molecular study, A. campestris var. campestris, A. campestris var. marschalliana and A. campestris var. araratica were proposed to be raised from the variety level to the species level. This research is important as it is the first molecular based study relating with the subgenus Dracunculus growing in Turkey.

scholarly journals Recent large-scale landscape changes, genetic drift and reintroductions characterize the genetic structure of Norwegian wild reindeer

2019 ◽  
Vol 20 (6) ◽  
pp. 1405-1419 ◽  
Author(s):  
Kjersti S. Kvie ◽  
Jan Heggenes ◽  
Bård-Jørgen Bårdsen ◽  
Knut H. Røed
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Structure ◽  
Population Size ◽  
Genetic Drift ◽  
Genetic Connectivity ◽  
Conservation Strategies ◽  
Landscape Changes ◽  
Anthropogenic Habitat ◽  
Wild Reindeer

Abstract Landscape changes, such as habitat loss and fragmentation, subdivide wild populations, reduce their size, and limit gene flow. These changes may further lead to depletion of genetic variation within populations as well as accelerating differentiation among populations. As a migratory species requiring large living areas, wild reindeer (Rangifer tarandus) is highly vulnerable to human activity. The number and continued presence of wild reindeer have been significantly reduced due to accelerating anthropogenic habitat modifications, as well as displacement in benefit of domesticated herds of the species. As a basis for future management strategies we assess genetic structure and levels of genetic variation in Norwegian wild reindeer by analysing 12 microsatellite loci and the mitochondrial control region in 21 management units with varying population sizes. Overall, both markers showed highly varying levels of genetic variation, with reduced variation in the smaller and more isolated populations. The microsatellite data indicated a relationship between population size and genetic variation. This relationship was positive and linear until a threshold for population size was reached at approximately 1500 reindeer. We found high levels of differentiation among most populations, indicating low levels of gene flow, but only a weak correlation between geographic and genetic distances. Our results imply that the genetic structure of Norwegian wild reindeer is mainly driven by recent colonization history, population size, as well as human-induced landscape fragmentation, restricting gene flow and leading to high levels of genetic drift. To sustain viable populations, conservation strategies should focus on genetic connectivity between populations.

Phylogeographic analysis reveals mito-nuclear discordance in Dasypterus intermedius

2020 ◽  
Vol 101 (5) ◽  
pp. 1400-1409 ◽  
Author(s):  
Sydney K Decker ◽  
Loren K Ammerman
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Sequence Data ◽  
Divergence Time ◽  
Secondary Contact ◽  
Nuclear Marker ◽  
Mitochondrial Sequence ◽  
Phylogeographic Analysis ◽  
The Family ◽  
Molecular Framework

Abstract Northern yellow bats (Dasypterus intermedius) are tree-roosting bats in the family Vespertilionidae comprised of two subspecies: D. intermedius intermedius and D. intermedius floridanus. The two subspecies are thought to be geographically separated. Due to their cryptic morphology, this hypothesis has never been tested and can benefit from being examined within a molecular framework. In this study, mitochondrial sequence data from 38 D. intermedius and nuclear sequence data from 14 D. intermedius from across their range were used to test the hypothesis that genetically defined groups correspond geographically with the two morphologically defined subspecies. Although high levels of divergence of the mitochondrial sequence (11.6%) suggest genetically distinct clusters sympatric in southern Texas, no genetic structure was recovered with the nuclear marker. Moreover, the mitochondrial sequence data recovered a paraphyletic relationship between the two subspecies of D. intermedius with the Cuban yellow bat (D. insularis), whereas no such paraphyly was recovered from analysis of the nuclear marker. Divergence time based on analyses of mitochondrial sequence for the two subspecies was approximately 5.5 Ma. The patterns observed are hypothesized to be the result of past isolation of lineages and secondary contact that is currently contributing to gene flow.

Immunological studies in an isolate in Hungary: Ivád. Frequency of blood groups, saliva secretion and antibody titers

1961 ◽  
Vol 10 (3) ◽  
pp. 321-330
Author(s):  
R. Backhausz ◽  
J. Nemeskéri
Keyword(s):  
Genetic Drift ◽  
Blood Groups ◽  
Random Genetic Drift ◽  
Prominent Feature ◽  
Gene Frequencies ◽  
Saliva Secretion ◽  
The Family ◽  
Antibody Titers

SummaryData are presented concerning the distribution of the ABO, MN and Rh blood groups and the saliva AB-secretion in the endogameous population of Ivád (Ivády family). Although a greater frequency of the A-, M-, and D-genes was observable, the differences between the Ivády family and the surrounding populations from where the family originated, were not significant. Isoagglutinin and bacterial agglutinin titres showed a narrower variation at Ivád than in Budapest. No agammaglobulinaemia or a higher frequency of Rhesus isoimmunization was observable. The most prominent feature of the Ivády isolate was the conservation of the original gene frequencies. The effect of random genetic drift or of selection was not demonstrable as far as the genes investigated are concerned.

Population fragmentation causes inadequate gene flow and increases extinction risk

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Gene Flow ◽  
Extinction Risk ◽  
Random Mating ◽  
Large Population ◽  
Isolated Population ◽  
Population Fragmentation ◽  
Single Population ◽  
Total Size ◽  
Limited Gene Flow

Most species now have fragmented distributions, often with adverse genetic consequences. The genetic impacts of population fragmentation depend critically upon gene flow among fragments and their effective sizes. Fragmentation with cessation of gene flow is highly harmful in the long term, leading to greater inbreeding, increased loss of genetic diversity, decreased likelihood of evolutionary adaptation and elevated extinction risk, when compared to a single population of the same total size. The consequences of fragmentation with limited gene flow typically lie between those for a large population with random mating and isolated population fragments with no gene flow.

scholarly journals Hierarchical Analysis of Genetic Structure in Native Fire Ant Populations: Results From Three Classes of Molecular Markers

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 643-655 ◽  
Author(s):  
Kenneth G Ross ◽  
Michael J B Krieger ◽  
D DeWayne Shoemaker ◽  
Edward L Vargo ◽  
Laurent Keller
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Solenopsis Invicta ◽  
Large Scale ◽  
Fire Ant ◽  
Nuclear Markers ◽  
Social Forms ◽  
Native Populations ◽  
Nest Level ◽  
Nuclear Differentiation

We describe genetic structure at various scales in native populations of the fire ant Solenopsis invicta using two classes of nuclear markers, allozymes and microsatellites, and markers of the mitochondrial genome. Strong structure was found at the nest level in both the monogyne (single queen) and polygyne (multiple queen) social forms using allozymes. Weak but significant microgeographic structure was detected above the nest level in polygyne populations but not in monogyne populations using both classes of nuclear markers. Pronounced mitochondrial DNA (mtDNA) differentiation was evident also at this level in the polygyne form only. These microgeographic patterns are expected because polygyny in ants is associated with restricted local gene flow due mainly to limited vagility of queens. Weak but significant nuclear differentiation was detected between sympatric social forms, and strong mtDNA differentiation also was found at this level. Thus, queens of each form seem unable to establish themselves in nests of the alternate type, and some degree of assortative mating by form may exist as well. Strong differentiation was found between the two study regions usinga all three sets of markers. Phylogeographic analyses of the mtDNA suggest that recent limitations on gene flow rather than longstanding barriers to dispersal are responsible for this large-scale structure.

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