Molecular analysis of plant migration and refugia in the Arctic

The arctic flora is thought to have originated during the Late Tertiary, ap proximately 3 million years ago. Plant migration routes during colonization of the Arctic are currently unknown, and uncertainty remains over where ar ctic plants survived Pleistocene glaciations. A phylogenetic analysis of ch loroplast DNA variation in the purple saxifrage (Saxifraga oppositifolia) i ndicates that this plant first occurred in the Arctic in western Beringia b efore it migrated east and west to achieve a circumpolar distribution. The geographical distribution of chloroplast DNA variation in the species suppo rts the hypothesis that, during Pleistocene glaciations, some plant refugia were Located in the Arctic as well as at more southern Latitudes.