Reconstruction of the colonization route from glacial refugium to the northern distribution range of the European butterfly Polyommatus coridon (Lepidoptera: Lycaenidae)

Genetic analyses are useful tools for reconstructing glacial distribution patterns and postglacial expansion corridors. However, little information is available about the latter. We reconstruct the expansion corridors of the butterfly Polyommatus coridon from its glacial refugium to the northern edge of its current distribution by comparing populations from southern Lower Saxony (central Germany) to other existing genetic data sets. The populations from Lower Saxony clearly belonged to a western lineage that expanded postglacially from the Adriatic‐Mediterranean region. They form part of a southern German group passing through the Burgundian Gap. In the southern German group, populations belong to a western subgroup. Therefore, expansion followed the Rhine valley and through Hesse, finally reaching southern Lower Saxony and western Thuringia in central Germany. Thus, we present a complete colonization route from the glacial refugium to the northern distribution range of P. coridon. Such data are useful for understanding the biogeographic structure and migration corridors for other mobile Mediterranean species.