Chloroplast and nuclear DNA variation on a circumpolar scale: migration history of the clonal Saxifraga cernua

Abstract

Vast areas of the Arctic were covered by ice during the Quaternary glaciations. Plant populations were repeatedly fragmented into refugia and differentiated genetically for long periods of time, followed hy large-scale expansion from refugia during each of the short-term interglacials. The present geographical structuring of their organellar and nuclear genomes may thus reflect where the plants survived and the migration routes followed during postglacial expansion. Saxifraga cernua is an arctic -alpine , perennial polyploid
with efficient vegetative reproduction via bulbils . It is distributed almost ubiquitously throughout the Arctic and has isolated occurrences in more southern mountain areas.