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Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Dynamics of drift, gene flow, and selection during speciation in Silene
Graham Muir1, Christopher J Dixon, Andrea L Harper
1Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, United Kingdom. graham.muir@plants.ox.ac.uk
Evolution; International Journal of Organic Evolution
|April 24, 2012
Summary
Speciation with gene flow remains complex. This study reveals that while gene flow occurs between Silene species, selection can maintain species boundaries by preventing adaptive alleles from crossing, indicating independent evolutionary paths.
Area of Science:
- Evolutionary Biology
- Population Genetics
Background:
- Speciation with gene flow is a key evolutionary process, but its underlying genetic mechanisms are not fully understood.
- Population differentiation (F(ST)) is often used to infer species boundaries, but its interpretation requires considering drift, gene flow, and selection dynamics.
Purpose of the Study:
- To investigate the mechanics of speciation with gene flow using a multigenic analysis.
- To examine gene flow and selection patterns in three closely related Silene species: S. latifolia, S. dioica, and S. diclinis.
Main Methods:
- Multigenic analysis of population differentiation (F(ST)) and gene flow.
- Comparative genomic analysis to detect signatures of selection across species.
Main Results:
- S. diclinis likely evolved in allopatry, while S. latifolia and S. dioica show evidence of isolation with bidirectional gene flow, possibly from parapatric speciation followed by sympatry.
- Independent instances of positive selection were detected at the same genetic locus in both S. latifolia and S. dioica.
- Despite gene flow, adaptive alleles at this locus did not introgress across species boundaries.
Conclusions:
- Species boundaries can be maintained by selection even in the presence of gene flow.
- Independent, species-specific selection at the same locus can drive diversification or parallel evolution.
- Understanding the interplay of drift, gene flow, and selection is crucial for interpreting genetic data in the context of speciation.
Related Concept Videos
02:16Genetics of Speciation
Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.
01:07Speciation Rates
Overview
01:31Formation of Species
Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the parent species, and barriers to reproduction will typically exist. There are two primary mechanisms, speciation with and without geographic isolation—allopatric and sympatric speciation, respectively.
02:29Hybrid Zones
Hybrid zones are narrow regions where two closely related species interact, mate, and produce hybrids. Relative to either parent species, hybrids may possess distinct phenotypic or genetic differences that impact their survival and reproductive success. The genetic variances introduced by hybridization influence species diversity and speciation processes within the hybrid zone.
02:39Gene Flow
Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.
01:09Mutation, Gene Flow, and Genetic Drift
In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).