A contact zone between two distinct Rana temporaria lineages in northern Germany

Abstract

Recolonization of northern Europe after last glaciations has left distinct marks on its biota, and several contact zones between different refugial-lineages have been identified. Earlier studies of the common frog (Rana temporaria) have revealed two old (c. 0.75 Myr) mitochondrial DNA (mtDNA) lineages occurring in Europe, but the location of the contact zone has not been identified. Here we have performed mtDNA haplotyping for individuals from Ave populations form the suspected contact zone area in northern Germany. The distributions of the eastern and western mtDNA haplotypes strongly support a secondary contact zone between these two lineages, situated in between the rivers Weser and Elbe. This finding contributes not only to our understanding of the biogeography of European fauna, but also offers an opportunity for studies of introgression across a relatively narrow contact zone.