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Phylogeography of Southern Water Vole (Arvicola sapidus): evidence for refugia within the Iberian glacial refugium?

Authors


  • Alejandro Centeno-Cuadros is interested on the study of genetic structure at different hierarchical scales (individual, population and species) and on current (e.g. landscape effects) and historical (phylogeographic) processes that might influence on the current distribution of genetic diversity of species. Miguel Delibes conducts research involved on the ecology, evolution and conservation of wildlife, mainly focused on the study of mammals. José A. Godoy is interested in the application of molecular markers to address ecological and evolutionary questions with a special focus on endangered vertebrate species and conservation biology.

Alejandro Centeno-Cuadros, Fax: +34 954 62 11 25; E-mail: acenteno@ebd.csic.es

Abstract

The role of Southern European peninsulas as glacial refugia for temperate species has been widely established, but phylogeographic patterns within refugia are being only recently addressed. Here we describe the phylogeographic patterns for Southern water vole (Arvicola sapidus) in its whole distribution across Iberia and France. Control region and cytochrome b sequences were obtained for 228 samples from 130 localities across Iberia and France. Eighty-five haplotypes were found in total yielding a high overall mitochondrial diversity (π = 0.027; H = 0.974). Phylogeographic structure was relatively shallow (3.1% average intraspecific divergence) with few supported clades and 95% and 90% maximum parsimony unconnected networks, but significant, as reflected in increased pairwise nucleotide divergences with distance (r = 0.197, P = 0.03) and significant autocorrelation up to ∼500 km. Spatial analysis of molecular variance analysis detected seven geographical groups explaining 43.73% of the total mitochondrial variation. We detected demographic expansions in three of these groups. A recent colonization of France from Iberia was suggested and estimated around 62 000 years bp by an isolation-with-migration model. Our results suggest the contribution of episodes of isolation in glacial subrefugia in Iberia, but seem to exclude a long-term isolation over successive glacial cycles. Phylogeographic divergence was probably tempered by relatively large population sizes and rapid and extensive mixing among subrefugia during interglacials, that might have eroded the phylogeographic structure accumulated at glacial peaks. Phenotypic differences in A. sapidus do not delineate historically isolated intraspecific divisions and do not warrant subspecific delimitations. Our results do support the existence of subrefugia within Iberia and their role in promoting intraspecific divergences.

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