title: Speciation in peripheral populations: effects of drift load and mating systems.
abstract: Speciation in peripheral populations has long been considered one of the most plausible scenarios for speciation with gene flow. In this study, however we identify two additional problems of peripatric speciation, as compared to the parapatric case, that may impede the completion of the speciation process for most parameter regions. First, with (predominantly) unidirectional gene flow, there is no selection pressure to evolve assortative mating on the continent. We discuss the implications of this for different mating schemes. Second, genetic load can build up in small populations. This can lead to extinction of the peripheral species, or generate selection pressure for lower assortative mating to avoid inbreeding. In this case, either a stable equilibrium with intermediate assortment evolves or there is cycling between phases of hybridization and phases of complete isolation.
authors.affiliation: Department of Mathematics, University of Vienna, Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Rettelbach
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Servedio
authors.affiliation: Department of Mathematics, University of Vienna, Vienna, Austria.|Max-Perutz-Laboratories, University of Vienna, Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Hermisson
mesh_terms: D051456:Gene Flow; D049810:Genetic Speciation; D006824:Hybridization, Genetic; D012098:Reproduction
keywords: assortative mating; drift load; local adaptation; peripatric speciation; reinforcement