Migration patterns and taxonomy of Dryas octopetala L. in the North Atlantic region

Abstract

The climatic fluctuations of the Quaternary have greatly influenced the distribution, composition and genetic structure of plant populations. Dryas octopetala sensu lato is an arctic-alpine plant belonging to a circumpolar genus where the species delimitation is disputed. In the present study, the genetic structure of D. octopetala plants (N = 292) from selected populations (N = 26) in the North Atlantic region was analysed using nine microsatellite markers to test for and discuss an independent western immigration route of North Western Norwegian populations and the taxonomic justification of D. babingtoniana. Population structure analyses revealed two main groups in D. octopetala in the North Atlantic region; a northern group and a southern group. These findings were further supported by principal coordinate and AMOVA analyses. The division into two groups probably reflect glacial survival in two different areas in the North Atlantic region. The analyses were ambiguous with regard to the question of an independent western immigration route for the North Western Norwegian populations of D. octopetala, and no evidence was found for the maintenance of more than one Dryas taxon (D. octopetala) in Scotland and North Western Norway. It is accordingly no justification for a babingtoniana-taxon at any taxonomic level.