STEHLIK, IVANA*, JOHANN JAKOB SCHNELLER, AND KONRAD BACHMANN. Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland. - Molecular evidence for nunatak survival of the high-alpine plant Eritrichium nanum within the Central Alps.
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