Fossil records (pollen, macroremains) and genetic structures based on molecular markers provide complementary data sets for elucidating the (post-)glacial histories of extant plant populations. Based on comparative studies using both data sources, this article focuses on the effects of postglacial recolonization on the genetic structures in common, widespread forest tree species in the Alpine range. We recall that at least at the continental level, the three large southern European peninsulas, Iberia, Italy and the Balkans, but also the Carpathians represented important refugial areas for many European tree species during the last glacial maximum. However, these refugia had a minimal impact on the recolonization of the Alpine range. In contrast, recent studies demonstrate that refugial areas in the proximity of the Alps, e.g. at their eastern and western ends, harbored prominent source populations of current occurrences of the dominant forest trees in the Alpine range. Furthermore, there is strong evidence that several species were able to maintain populations north of the Alps, such as in the Bohemian Massif. We advocate that the Alps did not necessarily represent a barrier to northward migration, since terrain for advancement from various refugia was available along the margins of this mountain range. Such migration patterns allowed diverged genetic lineages to meet, leading to increased genetic diversity in respective contact zones. This overview underlines how paleoecological and molecular genetic studies may complement each other to develop a more comprehensive vision of the postglacial history of forest trees in the Alpine range.
Potential Future Ranges of Tree Species in the Alps