Figure 3 in The genetic legacy of the Quaternary ice ages

Figure 3 The general position of some well­known hybrid zones in Europe, which show major clustering in Scandinavia, central Europe and the Alps. Other clusters are apparent in the Pyrenees and the Balkans. These suture zones are caused by commonalities of iceage refugia, rate of postglacial expansion and physical barriers. There is further subdivision in the southern regions.