title: The genetic architecture of hybrid incompatibilities and their effect on barriers to introgression in secondary contact.
abstract: Genetic incompatibilities are an important component of reproductive isolation. Although theoretical studies have addressed their evolution, little is known about their maintenance when challenged by potentially high migration rates in secondary contact. Although theory predicts that recombination can erode barriers, many empirical systems have been found to retain species-specific differences despite substantial gene flow. By simulating whole genomes in individuals of hybridizing species, we find that the genetic architecture of two contrasting models of epistatic hybrid incompatibilities and the context of hybridization can substantially affect species integrity and genomic heterogeneity. In line with theory, our results show that intergenomic incompatibilities break down rapidly by recombination, but can maintain genome-wide differentiation under very limited conditions. By contrast, intragenomic interactions that arise from genetic pathways can maintain species-specific differences even with high migration rates and gene flow, whereas introgression at large parts of the genome can simultaneously remain extensive, consistent with empirical observations. We discuss the importance of intragenomic interactions in speciation and consider how this form of epistatic fitness variation is implicated and supported by other theoretical and empirical studies. We further address the relevance of replicates and knowledge of context when investigating the genomics of speciation.
authors.affiliation: Department of Botany and Program in Ecology, University of Wyoming, Laramie, Wyoming 82071. d.lindtke@sheffield.ac.uk.|Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom. d.lindtke@sheffield.ac.uk.
authors.forename: Dorothea
authors.initials: D
authors.lastname: Lindtke
authors.affiliation: Department of Botany and Program in Ecology, University of Wyoming, Laramie, Wyoming 82071.
authors.forename: C Alex
authors.initials: CA
authors.lastname: Buerkle
mesh_terms: D005075:Biological Evolution; D003198:Computer Simulation; D004843:Epistasis, Genetic; D051456:Gene Flow; D049810:Genetic Speciation; D016678:Genome; D006824:Hybridization, Genetic; D008957:Models, Genetic; D060047:Reproductive Isolation; D013045:Species Specificity
keywords: Coadaptation; Dobzhansky-Muller incompatibilities; gene flow; genetic pathways; simulation; speciation