The contact zone between two migration routes of silver fir, Abies alba (Pinaceae), revealed by allozyme studies

Enzyme data from 35 populations or regional samples of Abies alba were obtained from different regions of Austria and Bavaria. The genetic analysis revealed a clear differentiation between the western and the north/eastern populations. A rather narrow transition zone (the river valleys of Salzach and Traun) with genetically intermediate populations connects these two regions. This west-east differentiation can be interpreted as the result of distinct migration routes from a glacial refuge in Central Italy. The transition zone is assumed to be the contact area of two routes north of the Alps. Each migration route of silver fir parallels the distribution range of Cardamine trifolia (east) and Aposeris foetida (west) respectively. It is supposed that these two species were already associated with silver fir during colonization.