Structure and dynamics of hybrid zones at multiple stages of speciation in the common vole (Microtus arvalis)

The genetic structure and dynamics of hybrid zones provides crucial information for the understanding of the processes and mechanisms of evolutionary divergence and speciation. In general, higher levels of evolutionary divergence between taxa are more likely to be associated with reproductive isolation and may result in suppressed or strongly restricted hybridization. In this study, we examined the structure and processes in two secondary contact zones between three deep evolutionary lineages in the common vole (Microtus arvalis). Differences in divergence times between the lineages have the potential to shed light on different stages of reproductive isolation and thus provide information on the ongoing speciation process in M. arvalis. We examined more than 800 individuals for mitochondrial (mtDNA), Y-chromosome and autosomal markers, and used assignment and cline analysis methods to characterize the extent and direction of gene flow in the contact zones. Introgression of both autosoma...