• Arctic;
  • clonal plants;
  • genetic diversity;
  • RAPDs;
  • Saxifraga cernua

Arctic plants in general and arctic clonal plants in particular have often been assumed to contain low levels of genetic diversity. We used RAPDs (random amplified polymorphic DNAs) to investigate genetic diversity in the arctic-alpine Saxifraga cernua, which mainly reproduces clonally via bulbils, at three spatial scales in Svalbard: (i) ‘macroscale’, between two sites 11 km apart; (ii) ‘mesoscale’, along two crossing transects at each site; and (iii) ‘microscale’, within a 3 × 3 m square at each site. Thirteen putative clones (RAPD phenotypes) were distinguished among 93 ramets based on 38 RAPD markers. The genetic diversity (D; mean 0.52, range 0.10–0.81) and evenness (E; mean 0.42, range 0.00–0.82) were at the same level as in clonal plants in general. However, the diversity strongly depended on site and spatial scale. Several clones were highly divergent and clustered independently of site in UPGMA and PCO analyses. In an analysis of molecular variance (AMOVA), most of the variation (59%) was found within sites. Mantel tests revealed no correlation between spatial and genetic distance within sites. Our results suggest that occasional sexual reproduction as well as clonal migration via bulbil dispersal play a significant role in the treeless arctic environment, where S. cernua is widespread and locally very abundant. In contrast, Bauert et al. (Molecular Ecology 7, 1519–1527) found no genetic variation within populations or regions of the Alps, where the species has highly isolated occurrences.