Geographical differentiation of Dryas octopetala in Europe based on morphological features.

Dryas octopetala is an important arctic alpine species, but its morphological analyses are scarce. The study deals with present European biogeographical structure based on morphology and its relations to the phylogenetic structure and the climate. Characters of leaves from 23 isolated populations were measured, statistically characterized and analyzed with the use of ANOVA and the discriminant analysis. All the features differentiated the tested samples significantly. Differences between plants representing regions were greater than between the samples within regions with regard to the four characters. The most visible division ran between the samples coming from the southern and the northern parts of the range, with the sample from the Western Scandinavia occupying the central position. Correlations between characters and climactic factors were shown, and the size of the leaf was associated mainly with the minimum temperatures of spring months, while the leaf shape with the rainfall during the summer months. Characters differentiating the regions and discriminating populations strongly were mostly dependent on the influence of the climate. The results of the present study were not fully consistent with the outcomes of the biogeographic molecular analyses of the researched species. Some parallels can be drawn when comparing the present analyses with the geographic differentiation of two other arctic-alpine shrubs Salix herbacea and S. reticulata. Although morphological diversity of Dryas octopetala showed a geographic structure, it was most probably shaped mainly by the influence of the environmental and climatic factors. [ABSTRACT FROM AUTHOR]