scholarly journals Establishment of locally adapted mutations under divergent selection

2018 ◽  
Author(s):  
Matteo Tomasini ◽  
Stephan Peischl
Keyword(s):  
Gene Flow ◽  
Local Adaptation ◽  
Migration Rate ◽  
Analytical Approximation ◽  
Multitype Branching Process ◽  
Process Framework ◽  
Establishment Probability ◽  
Two Populations ◽  
Closed Form Approximation

AbstractWe study the establishment probabilities of locally adapted mutations using a multitype branching process framework. We find a surprisingly simple and intuitive analytical approximation for the establishment probabilities in a symmetric two-deme model under the assumption of weak (positive) selection. This is the first analytical closed-form approximation for arbitrary migration rate to appear in the literature. We find that the establishment probability lies between the weak and the strong migration limits if we condition the origin of the mutation to the deme where it is advantageous. This is not the case when we condition the mutation to first occur in a deme where it is disadvantageous. In this case we find that an intermediate migration rate maximizes the probability of establishment. We extend our results to the cases of multiple demes, two demes with asymmetric rates of gene flow, and asymmetric carrying capacities. The latter case allows us to illustrate how density regulation can affect establishment probabilities. Finally we use our results to investigate the role of gene flow on the rate of local adaptation and identify cases in which intermediate amounts of gene flow facilitate the rate of local adaptation as compared to two populations without gene flow.

scholarly journals The limits to parapatric speciation 3: evolution of strong reproductive isolation in presence of gene flow despite limited ecological differentiation

2020 ◽  
Vol 375 (1806) ◽  
pp. 20190532 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Claudia Bank ◽  
Joachim Hermisson
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Theme Issue ◽  
Genetic Barrier ◽  
Incipient Species ◽  
Postzygotic Reproductive Isolation ◽  
Minimal Configuration ◽  
Parapatric Speciation ◽  
Two Populations

Gene flow tends to impede the accumulation of genetic divergence. Here, we determine the limits for the evolution of postzygotic reproductive isolation in a model of two populations that are connected by gene flow. We consider two selective mechanisms for the creation and maintenance of a genetic barrier: local adaptation leads to divergence among incipient species due to selection against migrants, and Dobzhansky–Muller incompatibilities (DMIs) reinforce the genetic barrier through selection against hybrids. In particular, we are interested in the maximum strength of the barrier under a limited amount of local adaptation, a challenge that many incipient species may initially face. We first confirm that with classical two-locus DMIs, the maximum amount of local adaptation is indeed a limit to the strength of a genetic barrier. However, with three or more loci and cryptic epistasis, this limit holds no longer. In particular, we identify a minimal configuration of three epistatically interacting mutations that is sufficient to confer strong reproductive isolation. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers’.

scholarly journals The role of gene flow asymmetry along an environmental gradient in constraining local adaptation and range expansion

2012 ◽  
Vol 25 (8) ◽  
pp. 1676-1685 ◽  
Author(s):  
K. M. FEDORKA ◽  
W. E. WINTERHALTER ◽  
K. L. SHAW ◽  
W. R. BROGAN ◽  
T. A. MOUSSEAU
Keyword(s):  
Gene Flow ◽  
Local Adaptation ◽  
Range Expansion ◽  
Environmental Gradient ◽  
Flow Asymmetry

scholarly journals Assortative mating and the role of phenotypic plasticity in male competition: implications for gene flow among host-associated parasitoid populations

2008 ◽  
Vol 4 (5) ◽  
pp. 508-511 ◽  
Author(s):  
Lee M Henry
Keyword(s):  
Gene Flow ◽  
Phenotypic Plasticity ◽  
Local Adaptation ◽  
Assortative Mating ◽  
Host Species ◽  
Relative Size ◽  
Mating Preference ◽  
Adult Males ◽  
Mating Preferences

Local adaptation is promoted when habitat or mating preferences reduce gene flow between populations. However, gene flow is not only a function of dispersal but also of the success of migrants in their new habitat. In this study I investigated mating preference in conjunction with phenotypic plasticity using Aphidius parasitoids adapted to different host species. Males actively attempted to assortatively mate, but actual mating outcomes were strongly influenced by the relative size of the adult males. Results are discussed in the context of assortative mating in combination with the success of migrant males in mitigating gene flow between host-associated parasitoid populations.

scholarly journals The limits to parapatric speciation 3: Evolution of strong reproductive isolation in presence of gene flow despite limited ecological differentiation

2020 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Claudia Bank ◽  
Joachim Hermisson
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Maximum Amount ◽  
Genetic Barrier ◽  
Incipient Species ◽  
Postzygotic Reproductive Isolation ◽  
Minimal Configuration ◽  
Parapatric Speciation ◽  
Two Populations

AbstractGene flow tends to impede the accumulation of genetic divergence. Here, we determine the limits for the evolution of postzygotic reproductive isolation in a model of two populations that are connected by gene flow. We consider two selective mechanisms for the creation and maintenance of a genetic barrier: local adaptation leads to divergence among incipient species due to selection against migrants, and Dobzhansky-Muller incompatibilities (DMIs) reinforce the genetic barrier through selection against hybrids. In particular, we are interested in the maximum strength of the barrier under a limited amount of local adaptation, a challenge that may initially face many incipient species. We first confirm that with classical two-locus DMIs, the maximum amount of local adaptation is indeed a limit to the strength of a genetic barrier. However, with three or more loci and cryptic epistasis, this limit holds no longer. In particular, we identify a minimal configuration of three epistatically interacting mutations that is sufficient to confer strong reproductive isolation.

scholarly journals Consequences of gene flow in spatially structured populations

1997 ◽  
Vol 69 (1) ◽  
pp. 49-60 ◽  
Author(s):  
KATRINA A. LYTHGOE
Keyword(s):  
Gene Flow ◽  
Simple Model ◽  
Migration Rate ◽  
Genetic Variance ◽  
Structured Populations ◽  
Stabilizing Selection ◽  
Heritable Variation ◽  
Fluctuating Selection ◽  
Spatially Structured Populations ◽  
Two Populations

A simple model of migration between two populations, each in a balance between mutation and stabilizing selection on a polygenic trait, is explored. Below a critical migration rate, genetic differences between the two populations can be maintained, even if the populations are selected towards the same phenotypic optimum. Gene flow then maintains genetic variance within each population. For this process to account for heritable variation, there must be some mechanism that causes divergence. The possibility that fluctuating selection could lead to the initial differentiation of the populations is explored.

scholarly journals The impact of global selection on local adaptation and reproductive isolation

2019 ◽  
Author(s):  
Gertjan Bisschop ◽  
Derek Setter ◽  
Marina Rafajlović ◽  
Stuart J.E. Baird ◽  
Konrad Lohse
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Genetic Load ◽  
Divergent Selection ◽  
Mutation Process ◽  
Genome Wide ◽  
The Impact ◽  
Two Populations ◽  
Global Selection

AbstractDespite the homogenising effect of strong gene flow between two populations, adaptation under symmetric divergent selection pressures results in partial reproductive isolation: adaptive substitutions act as local barriers to gene flow, and if divergent selection continues unimpeded, this will result in complete reproductive isolation of the two populations, i.e. speciation. However, a key issue in framing the process of speciation as a tension between local adaptation and the homogenising force of gene flow is that the mutation process is blind to changes in the environment and therefore tends to limit adaptation. Here we investigate how globally beneficial mutations (GBMs) affect divergent local adaptation and reproductive isolation. When phenotypic divergence is finite, we show that the presence of GBMs limits local adaptation, generating a persistent genetic load at the loci which contribute to the trait under divergent selection and reducing genome-wide divergence. Furthermore, we show that while GBMs cannot prohibit the process of continuous differentiation, they induce a substantial delay in the genome-wide shutdown of gene flow.

scholarly journals The impact of global selection on local adaptation and reproductive isolation

2020 ◽  
Vol 375 (1806) ◽  
pp. 20190531 ◽  
Author(s):  
Gertjan Bisschop ◽  
Derek Setter ◽  
Marina Rafajlović ◽  
Stuart J. E. Baird ◽  
Konrad Lohse
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Genetic Load ◽  
Divergent Selection ◽  
Mutation Process ◽  
Genome Wide ◽  
The Impact ◽  
Two Populations ◽  
Global Selection

Despite the homogenizing effect of strong gene flow between two populations, adaptation under symmetric divergent selection pressures results in partial reproductive isolation: adaptive substitutions act as local barriers to gene flow, and if divergent selection continues unimpeded, this will result in complete reproductive isolation of the two populations, i.e. speciation. However, a key issue in framing the process of speciation as a tension between local adaptation and the homogenizing force of gene flow is that the mutation process is blind to changes in the environment and therefore tends to limit adaptation. Here we investigate how globally beneficial mutations (GBMs) affect divergent local adaptation and reproductive isolation. When phenotypic divergence is finite, we show that the presence of GBMs limits local adaptation, generating a persistent genetic load at the loci that contribute to the trait under divergent selection and reducing genome-wide divergence. Furthermore, we show that while GBMs cannot prohibit the process of continuous differentiation, they induce a substantial delay in the genome-wide shutdown of gene flow. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers’.

scholarly journals Premating barriers in young sympatric snail species

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arina L. Maltseva ◽  
Marina A. Varfolomeeva ◽  
Arseniy A. Lobov ◽  
Polina O. Tikanova ◽  
Egor A. Repkin ◽  
...  
Keyword(s):  
Gene Flow ◽  
Snail Species ◽  
Sympatric Populations ◽  
Gastropod Species ◽  
Shell Size ◽  
Closely Related Species ◽  
Partial Canonical Correspondence Analysis ◽  
In The Wild ◽  
Isolation Index

AbstractSympatric coexistence of recently diverged species raises the question of barriers restricting the gene flow between them. Reproductive isolation may be implemented at several levels, and the weakening of some, e.g. premating, barriers may require the strengthening of the others, e.g. postcopulatory ones. We analysed mating patterns and shell size of mates in recently diverged closely related species of the subgenus Littorina Neritrema (Littorinidae, Caenogastropoda) in order to assess the role of premating reproductive barriers between them. We compared mating frequencies observed in the wild with those expected based on relative densities using partial canonical correspondence analysis. We introduced the fidelity index (FI) to estimate the relative accuracy of mating with conspecific females and precopulatory isolation index (IPC) to characterize the strength of premating barriers. The species under study, with the exception of L. arcana, clearly demonstrated preferential mating with conspecifics. According to FI and IPC, L. fabalis and L. compressa appeared reliably isolated from their closest relatives within Neritrema. Individuals of these two species tend to be smaller than those of the others, highlighting the importance of shell size changes in gastropod species divergence. L. arcana males were often found in pairs with L. saxatilis females, and no interspecific size differences were revealed in this sibling species pair. We discuss the lack of discriminative mate choice in the sympatric populations of L. arcana and L. saxatilis, and possible additional mechanisms restricting gene flow between them.

scholarly journals Microtubule–microtubule sliding by kinesin-1 is essential for normal cytoplasmic streaming in Drosophila oocytes

2016 ◽  
Vol 113 (34) ◽  
pp. E4995-E5004 ◽  
Author(s):  
Wen Lu ◽  
Michael Winding ◽  
Margot Lakonishok ◽  
Jill Wildonger ◽  
Vladimir I. Gelfand
Keyword(s):  
Cytoplasmic Streaming ◽  
Cell Types ◽  
Nurse Cells ◽  
Wild Type ◽  
Actin Cortex ◽  
Microtubule Motor ◽  
Multiple Cell ◽  
Cytoplasmic Microtubules ◽  
Two Populations

Cytoplasmic streaming in Drosophila oocytes is a microtubule-based bulk cytoplasmic movement. Streaming efficiently circulates and localizes mRNAs and proteins deposited by the nurse cells across the oocyte. This movement is driven by kinesin-1, a major microtubule motor. Recently, we have shown that kinesin-1 heavy chain (KHC) can transport one microtubule on another microtubule, thus driving microtubule–microtubule sliding in multiple cell types. To study the role of microtubule sliding in oocyte cytoplasmic streaming, we used a Khc mutant that is deficient in microtubule sliding but able to transport a majority of cargoes. We demonstrated that streaming is reduced by genomic replacement of wild-type Khc with this sliding-deficient mutant. Streaming can be fully rescued by wild-type KHC and partially rescued by a chimeric motor that cannot move organelles but is active in microtubule sliding. Consistent with these data, we identified two populations of microtubules in fast-streaming oocytes: a network of stable microtubules anchored to the actin cortex and free cytoplasmic microtubules that moved in the ooplasm. We further demonstrated that the reduced streaming in sliding-deficient oocytes resulted in posterior determination defects. Together, we propose that kinesin-1 slides free cytoplasmic microtubules against cortically immobilized microtubules, generating forces that contribute to cytoplasmic streaming and are essential for the refinement of posterior determinants.

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