Two main possibilities of glacial survival of the mountain flora of the European Alps during the Quaternary have been proposed: the tabula rasa and the nunatak hypotheses. Eritrichium nanum (L.) Gaudin (Boraginaceae) is a perennial cushion plant occurring at high elevations of the Central Alps and having a preference for extreme habitats. It belongs to a group of high-alpine plants, for which in-situ glacial survival on nunataks has been suggested. By investigating 20 populations of E. nanum from potential nunatak and refugial regions using AFLPs, substantial genetic differences between populations from the Central Alps and populations from peripheral refugia in the Southern Alps were detected, excluding the latter as potential sources for the recolonization of the Central Alps after glaciation. Genetic variation was hierarchically structured (AMOVA), and three genetically separated regions could be identified in the Central Alps. Two of these, the Penninic and Rhaetic Alps, correspond to narrow nunatak regions formerly proposed in the biogeographic literature. Populations from the Lepontic Alps formed a third, separate genetic group. Genetic correlation (Mantel test) was highest within populations, showing a modest decline among populations within specific nunatak regions and a negative correlation outside the radius of the 'genetic influence' of specific nunatak regions. The present demonstration of in-situ glacial survival in E. nanum could be exemplary for the Quaternary history of other alpine plants, especially those occurring at high elevations and in similar habitats as E. nanum.

Key words: AFLP, alpine species, Boraginaceae, Eritrichium nanum, historical biogeography, Quaternary glacial survival