The effects of sexual selection on trait divergence in a peripheral population with gene flow.
The unique aspects of speciation and divergence in peripheral populations have long sparked much research. Unidirectional migration, received by some peripheral populations, can hinder the evolution of distinct differences from their founding populations. Here, we explore the effects that sexual selection, long hypothesized to drive the divergence of distinct traits used in mate choice, can play in the evolution of such traits in a partially isolated peripheral population. Using population genetic continent-island models, we show that with phenotype matching, sexual selection increases the frequency of an island-specific mating trait only when female preferences are of intermediate strength. We identify regions of preference strength for which sexual selection can instead cause an island-specific trait to be lost, even when it would have otherwise been maintained at migration-selection balance. When there are instead separate preference and trait loci, we find that sexual selection can lead to low trait frequencies or trait loss when female preferences are weak to intermediate, but that sexual selection can increase trait frequencies when preferences are strong. We also show that novel preference strengths almost universally cannot increase, under either mating mechanism, precluding the evolution of premating isolation in peripheral populations at the early stages of species divergence.
Department of Biology, University of North Carolina, Chapel Hill, North Carolina, 27599. servedio@email.unc.edu.
Maria R
MR
Servedio
Department of Mathematics, University of Vienna, Oskar-Morgenstern-Platz 1, 1090, Vienna, Austria.
Reinhard
R
Bürger
D025041:Animal Migration; D000818:Animals; D005075:Biological Evolution; D005260:Female; D051456:Gene Flow; D049810:Genetic Speciation; D005828:Genetics, Population; D008297:Male; D052586:Mating Preference, Animal; D008957:Models, Genetic; D010641:Phenotype; D012098:Reproduction / Q000235:genetics; D012641:Selection, Genetic
Assortative mating; continent-island model; mate choice; phenotype matching; preference; speciation