title: The evolution of recombination rates in finite populations during ecological speciation.
abstract: Recombination can impede ecological speciation with gene flow by mixing locally adapted genotypes with maladapted migrant genotypes from a divergent population. In such a scenario, suppression of recombination can be selectively favoured. However, in finite populations evolving under the influence of random genetic drift, recombination can also facilitate adaptation by reducing Hill-Robertson interference between loci under selection. In this case, increased recombination rates can be favoured. Although these two major effects on recombination have been studied individually, their joint effect on ecological speciation with gene flow remains unexplored. Using a mathematical model, we investigated the evolution of recombination rates in two finite populations that exchange migrants while adapting to contrasting environments. Our results indicate a two-step dynamic where increased recombination is first favoured (in response to the Hill-Robertson effect), and then disfavoured, as the cost of recombining locally with maladapted migrant genotypes increases over time (the maladaptive gene flow effect). In larger populations, a stronger initial benefit for recombination was observed, whereas high migration rates intensify the long-term cost of recombination. These dynamics may have important implications for our understanding of the conditions that facilitate incipient speciation with gene flow and the evolution of recombination in finite populations.
authors: School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors: James
authors: J
authors: Reeve
authors: School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors: Daniel
authors: 0000-0002-7493-416X
authors: D
authors: Ortiz-Barrientos
authors: School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia j.engelstaedter@uq.edu.au.
authors: Jan
authors: 0000-0003-3340-918X
authors: J
authors: Engelstädter
mesh_terms: D000222:Adaptation, Physiological; D051456:Gene Flow; D040961:Genetic Drift; D049810:Genetic Speciation; D008957:Models, Genetic; D011995:Recombination, Genetic; D012641:Selection, Genetic
keywords: Hill–Robertson effect; adaptive divergence; maladaptive gene flow; mathematical model; random genetic drift; recombination modifier