Comparative phylogeography of land snail species in mountain refugia in the European Southern Alps

Abstract

AbstractAimWe investigated the location of Pleistocene mountain refugia in the European Southern Alps based on distribution data for four endemic land snail taxa and tested the hypothesis that the subdivision of species into endemic subspecies may be attributed to the same vicariance events.LocationThe European Southern Alps between Lago di Como and Lago di Garda in Italy.MethodsWe compiled distributional data for four land snail species (Cochlostoma porroi, Clausilia brembina, Clausilia whateliana and Charpentieria itala), which are subdivided into endemic subspecies in the study region, and investigated to what extent their distribution areas are congruent and correspond to regions that remained unglaciated during the glacials. To examine also whether their phylogeographic patterns are concordant, as would be expected if the subdivision of the species was caused by the same vicariance events, we reconstructed the phylogenetic relationships between the subspecies of the four species using 16S rDNA sequences and amplified fragment length polymorphism (AFLP) data.ResultsThe endemic subspecies were found to be concentrated in mountain regions that remained unglaciated during the glacials, consistent with these regions acting as Pleistocene refugia for these snails. Although the Oglio glacier did not equally affect the differentiation of the investigated species, the repeated contractions of their ranges into these refugia resulted in similar patterns of colonization and differentiation.Main conclusionsClimate change such as the recurrent glaciations during the Pleistocene can result in similar distribution and colonization patterns, but the patterns in different species and their evolutionary trajectories are rarely completely identical because of their different histories, the randomness of dispersal, and small differences in ecology or dispersal capability.