GENETIC HITCHHIKING AND THE DYNAMIC BUILDUP OF GENOMIC DIVERGENCE DURING SPECIATION WITH GENE FLOW
Authored by Samuel M Flaxman, Jeffrey L Feder, Patrik Nosil
Date Published: 2013
DOI: 10.1111/evo.12055
Sponsors:
European Research Council (ERC)
United States Department of Agriculture (USDA)
United States National Science Foundation (NSF)
Platforms:
C
Model Documentation:
Other Narrative
Model Code URLs:
https://sourceforge.net/projects/bu2s/files/
Abstract
A major issue in evolutionary biology is explaining patterns of
differentiation observed in population genomic data, as divergence can
be due to both direct selection on a locus and genetic hitchhiking.
Divergence hitchhiking (DH) theory postulates that divergent selection
on a locus reduces gene flow at physically linked sites, facilitating
the formation of localized clusters of tightly linked, diverged loci.
Genome hitchhiking (GH) theory emphasizes genome-wide effects of
divergent selection. Past theoretical investigations of DH and GH
focused on static snapshots of divergence. Here, we used simulations
assessing a variety of strengths of selection, migration rates, population sizes, and mutation rates to investigate the relative
importance of direct selection, GH, and DH in facilitating the dynamic
buildup of genomic divergence as speciation proceeds through time. When
divergently selected mutations were limiting, GH promoted divergence, but DH had little measurable effect. When populations were small and
divergently selected mutations were common, DH enhanced the accumulation
of weakly selected mutations, but this contributed little to
reproductive isolation. In general, GH promoted reproductive isolation
by reducing effective migration rates below that due to direct selection
alone, and was important for genome-wide congealing or coupling of
differentiation (F-ST) across loci as speciation progressed.
Tags
Migration
Evolution
models
Populations
Consequences
Natural-selection
Establishment
Ecological speciation
Local
adaptation
Threespine stickleback