Effects of Population Bottlenecks on Genetic Diversity as Measured by Allozyme Electrophoresis

Evolution ◽  
1992 ◽  
Vol 46 (2) ◽  
pp. 477 ◽  
Author(s):  
Paul L. Leberg
Keyword(s):  
Genetic Diversity ◽  
Population Bottlenecks ◽  
Allozyme Electrophoresis

Genetic variation in the greater bilby (Macrotis lagotis)

1994 ◽  
Vol 1 (1) ◽  
pp. 46 ◽  
Author(s):  
Richard Southgate ◽  
Mark Adams
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Variability ◽  
Population Genetic ◽  
Taxonomic Status ◽  
Biological Species ◽  
Significant Loss ◽  
Allozyme Electrophoresis ◽  
Allozyme Data ◽  
Data Support

The taxonomic status of and genetic diversity amongst extant populations of the greater bilby, Macrotis lagotis, were assessed using allozyme electrophoresis. A total of 47 bilbies sampled from three geographic areas and two captive colonies were screened for 42 loci, six of which were polymorphic. The results are consistent with the view that all extant populations represent a single biological species. All populations were genetically very similar (Nei D's 0.000 to 0.004) and overall levels of within-population genetic variability were low (Ho 0.004 � 0.004 to 0.0026 � 0.017). The allozyme data support the hypothesis that there has been no significant loss of variability in the captive colonies when compared to the species as a whole.

scholarly journals Evolutionary dynamics of human and avian metapneumoviruses

2008 ◽  
Vol 89 (12) ◽  
pp. 2933-2942 ◽  
Author(s):  
Miranda de Graaf ◽  
Albert D. M. E. Osterhaus ◽  
Ron A. M. Fouchier ◽  
Edward C. Holmes
Keyword(s):  
Genetic Diversity ◽  
Evolutionary Dynamics ◽  
Recent Common Ancestor ◽  
Human Populations ◽  
Population Bottlenecks ◽  
Genetic Lineages ◽  
The Past ◽  
Most Recent Common Ancestor ◽  
Large Sets ◽  
Respiratory Tract Illnesses

Human (HMPV) and avian (AMPV) metapneumoviruses are closely related viruses that cause respiratory tract illnesses in humans and birds, respectively. Although HMPV was first discovered in 2001, retrospective studies have shown that HMPV has been circulating in humans for at least 50 years. AMPV was first isolated in the 1970s, and can be classified into four subgroups, A–D. AMPV subgroup C is more closely related to HMPV than to any other AMPV subgroup, suggesting that HMPV has emerged from AMPV-C upon zoonosis. Presently, at least four genetic lineages of HMPV circulate in human populations – A1, A2, B1 and B2 – of which lineages A and B are antigenically distinct. We used a Bayesian Markov Chain Monte Carlo (MCMC) framework to determine the evolutionary and epidemiological dynamics of HMPV and AMPV-C. The rates of nucleotide substitution, relative genetic diversity and time to the most recent common ancestor (TMRCA) were estimated using large sets of sequences of the nucleoprotein, the fusion protein and attachment protein genes. The sampled genetic diversity of HMPV was found to have arisen within the past 119–133 years, with consistent results across all three genes, while the TMRCA for HMPV and AMPV-C was estimated to have existed around 200 years ago. The relative genetic diversity observed in the four HMPV lineages was low, most likely reflecting continual population bottlenecks, with only limited evidence for positive selection.

scholarly journals The effect of population bottleneck size and selective regime on genetic diversity and evolvability in bacteria

2019 ◽  
Author(s):  
Tanita Wein ◽  
Tal Dagan
Keyword(s):  
Genetic Diversity ◽  
Genetic Drift ◽  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Population Bottleneck ◽  
Population Bottlenecks ◽  
High Genetic Diversity ◽  
Temperature Regimes ◽  
Consequent Reduction ◽  
History Of

AbstractPopulation bottlenecks leading to a drastic reduction of the population size are common in the evolutionary dynamics of natural populations; their occurrence is known to have implications for genome evolution due to genetic drift, the consequent reduction in genetic diversity and the rate of adaptation. Nevertheless, an empirical characterization of the effect of population bottleneck size on evolutionary dynamics of bacteria is currently lacking. Here we show that selective conditions have a stronger effect on the evolutionary history of bacteria in comparison to genetic drift following population bottlenecks. We evolved Escherichia coli populations under three different population bottlenecks (small, medium, large) in two temperature regimes (37°C and 20°C). We find a high genetic diversity in the large in comparison to the small bottleneck size. Nonetheless, the cold temperature led to reduced genetic diversity in all bottleneck sizes, hence, the temperature has a stronger effect on the genetic diversity in comparison to the bottleneck size. A comparison of the fitness gain among the evolved populations reveals a similar pattern where the temperature has a significant effect on the fitness. Our study demonstrates that population bottlenecks are an important determinant of the evolvability in bacteria; their consequences depend on the selective conditions and are best understood via their effect on the standing genetic variation.

scholarly journals Molecular evolutionary consequences of island colonisation

2015 ◽  
Author(s):  
Jennifer James ◽  
Robert Lanfear ◽  
Adam Eyre-Walker
Keyword(s):  
Genetic Diversity ◽  
Population Bottleneck ◽  
Surprising Result ◽  
Population Bottlenecks ◽  
Adaptive Potential ◽  
Effective Population ◽  
Island Species ◽  
Population Sizes ◽  
Evolutionary Consequences ◽  
The Relationship

Island endemics are likely to experience population bottlenecks; they also have restricted ranges. Therefore we expect island species to have small effective population sizes (Ne) and reduced genetic diversity compared to their mainland counterparts. As a consequence, island species may have inefficient selection and reduced adaptive potential. We used both polymorphisms and substitutions to address these predictions, improving on the approach of recent studies that only used substitution data. This allowed us to directly test the assumption that island species have small values of Ne. We found that island species had significantly less genetic diversity than mainland species; however, this pattern could be attributed to a subset of island species that had undergone a recent population bottleneck. When these species were excluded from the analysis, island and mainland species had similar levels of genetic diversity, despite island species occupying considerably smaller areas than their mainland counterparts. We also found no overall difference between island and mainland species in terms of effectiveness of selection or mutation rate. Our evidence suggests that island colonisation has no lasting impact on molecular evolution. This surprising result highlights gaps in our knowledge of the relationship between census and effective population size.

scholarly journals Interspecific Comparisons of Genetic Population Structure in Members of the Jaera Albifrons Species Complex

1997 ◽  
Vol 77 (1) ◽  
pp. 77-93 ◽  
Author(s):  
Gary R. Carvalho ◽  
Stuart B. Piertney
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Differentiation ◽  
Species Complex ◽  
Niche Width ◽  
Allozyme Electrophoresis ◽  
Genetic Population ◽  
Interspecific Comparisons ◽  
The Relationship ◽  
Variability Data

Marked genetic differentiation in the intertidal isopod, Jaera albifrons (Crustacea: Isopoda) has been shown to occur on a scale of just a few metres on British shores. Allozyme electrophoresis at 21 enzyme-coding loci has been employed to examine genetic structure in other UK members of the complex (Jaera forsmani, J. ischiosetosa, J. praehirsuta), and explore the relationship between genetic diversity and perceived niche-width. Comparisons were made with the nonsibling species J. nordmanni. Three subpopulations of each species taken from each of two shores on Anglesey, UK (subpopulations N=30) were assayed for electrophoretic variability. Data from 11 polymorphic loci (P0·95) demonstrated marked genetic differentiation in all populations of J. albifrons and J. praehirsuta, and on one shore for each of J. ischiosetosa and J. nordmanni, with J. praehirsuta (GST=0·207) and J. albifrons (GST=0·121) showing the highest genetic differentiation. In contrast, J. forsmani exhibited population homogeneity on both shores studied. Genetic diversity ranged markedly across species (H0=0·165—0·040), with the two most widely distributed species, J. albifrons (H0=0·135) and J. ischiosetosa (Ho=0·165) exhibiting the highest genetic variability, providing support for the niche-width variation hypothesis. Data indicate that although habitat fragmentation and direct development is associated with microgeographic differentiation in Jaera spp., localized factors such as habitat continuity and exposure to water movements determines the magnitude of such effects.

scholarly journals Bachelor groups in primate multilevel society facilitate gene flow across fragmented habitats

2020 ◽  
Vol 66 (2) ◽  
pp. 113-122 ◽  
Author(s):  
Yu-Li Li ◽  
Lu Wang ◽  
Jin-Wei Wu ◽  
Xin-Ping Ye ◽  
Paul A Garber ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Habitat Fragmentation ◽  
Ecological Factors ◽  
Primate Species ◽  
Population Bottlenecks ◽  
Landscape Resistance ◽  
Resistance Surface ◽  
Multilevel Society ◽  
The Face

Abstract In the face of ongoing habitat fragmentation, many primate species have experienced reduced gene flow resulting in a reduction of genetic diversity, population bottlenecks, and inbreeding depression, including golden snub-nosed monkeys Rhinopithecus roxellana. Golden snub-nosed monkeys live in a multilevel society composed of several 1 male harem units that aggregate to form a cohesive breeding band, which is followed by one or more bachelor groups composed of juvenile, subadult, and adult male members. In this research, we examine the continuous landscape resistance surface, the genetic diversity and patterns of gene flow among 4 isolated breeding bands and 1 all-male band in the Qinling Mountains, China. Landscape surface modeling suggested that human activities and ecological factors severely limit the movement of individuals among breeding bands. Although these conditions are expected to result in reduced gene flow, reduced genetic diversity, and an increased opportunity for a genetic bottleneck, based on population genetic analyses of 13 microsatellite loci from 188 individuals inhabiting 4 isolated breeding bands and 1 all-male band, we found high levels of genetic diversity but low levels of genetic divergence, as well as high rates of gene flow between males residing in the all-male band and each of the 4 breeding bands. Our results indicate that the movement of bachelor males across the landscape, along with their association with several different breeding bands, appears to provide a mechanism for promoting gene flows and maintaining genetic diversity that may counteract the otherwise isolating effects of habitat fragmentation.

scholarly journals Genetic consequences of subtropical rainforest fragmentation on Macadamia tetraphylla (Proteaceae)

2011 ◽  
Vol 60 (1-6) ◽  
pp. 241-249 ◽  
Author(s):  
C. S. Spain ◽  
A. J. Lowe
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Population Differentiation ◽  
Adult Population ◽  
Population Divergence ◽  
Population Bottlenecks ◽  
Significant Difference ◽  
Adult Tree ◽  
Eventual Loss

Abstract Habitat fragmentation can bring about a variety of gene-flow alterations in plant populations, potentially threatening adaptive potential and local persistence. It is expected that following habitat fragmentation an increased level of inbreeding will be evident. In addition, a reduction in genetic diversity and increased genetic differentiation is expected following severe or long term population bottlenecks. We examined population genetic parameters for the subtropical rainforest tree Macadamia tetraphylla (Proteaceae) at six field sites throughout its recently fragmented range, using four microsatellite loci. Genetic diversity (HE) of the juvenile cohort was significantly correlated with estimated population size. No significant difference was observed for genetic diversity between adult and juvenile cohorts, but juveniles, and not adults, exhibited significant population differentiation (θ =0.061; P<0.0001 and θ =0.016; P=0.23, respectively). A second, standardised measure of differentiation, ×′, yielded similarly large differences between the two cohorts, though higher estimates of differentiation overall (adults – θ′=0.034, juveniles – θ′=0.116). The coefficient of population inbreeding (f) was significant and positive in all juvenile, and four out of six adult, populations, and was significantly positively correlated with adult tree density, but not adult population size. Since fragmentation is relatively recent for this species, the population bottleneck must have been quite severe to have produced the observed patterns of population differentiation and genetic diversity. Fragmentation of forest across the study area over the last 100+ years has led to the genetic isolation of M. tetraphylla populations resulting in increased population divergence and likely eventual loss of genetic variation in future generations.

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