title: Bounds to parapatric speciation: A Dobzhansky-Muller incompatibility model involving autosomes, X chromosomes, and mitochondria.
abstract: We investigate the conditions for the origin and maintenance of postzygotic isolation barriers, so called (Bateson-)Dobzhansky-Muller incompatibilities or DMIs, among populations that are connected by gene flow. Specifically, we compare the relative stability of pairwise DMIs among autosomes, X chromosomes, and mitochondrial genes. In an analytical approach based on a continent-island framework, we determine how the maximum permissible migration rates depend on the genomic architecture of the DMI, on sex bias in migration rates, and on sex-dependence of allelic and epistatic effects, such as dosage compensation. Our results show that X-linkage of DMIs can enlarge the migration bounds relative to autosomal DMIs or autosome-mitochondrial DMIs, in particular in the presence of dosage compensation. The effect is further strengthened with male-biased migration. This mechanism might contribute to a higher density of DMIs on the X chromosome (large X-effect) that has been observed in several species clades. Furthermore, our results agree with empirical findings of higher introgression rates of autosomal compared to X-linked loci.
authors.affiliation: Mathematics and BioSciences Group, Faculty of Mathematics and Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.|Vienna Graduate School of Population Genetics, Vienna, Austria.
authors.forename: Ilse
authors.initials: I
authors.lastname: Höllinger
authors.affiliation: Mathematics and BioSciences Group, Faculty of Mathematics and Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.
authors.forename: Joachim
authors.initials: J
authors.lastname: Hermisson
mesh_terms: D000818:Animals; D005260:Female; D018628:Gene Dosage; D051456:Gene Flow; D016678:Genome; D008297:Male; D008928:Mitochondria; D008957:Models, Genetic; D014960:X Chromosome
keywords: Hybrid incompatibility; Introgression on X and autosomes; Large X-effect; Speciation-with-gene-flow; Two-locus DMI