PHYLOGENY OF THE ARVICOLIDAE (RODENTIA) - BIOCHEMICAL AND PALEONTOLOGICAL EVIDENCE

Genetic distances between 24 arvicolid species of eight genera were estimated by electrophoretic comparison of homologous proteins. A dendrogram was constructed. This dendrogram was compared to the phylogeny of the Arvicolidae as inferred from the fossil record. In many respects, biochemical criteria support current views on arvicolid evolution, including the homogeneity of the family, a fact that agrees with the recent origin of the Arvicolidae (5 106 years). They also agree with the early divergence of the branches that lead to Dicrostonyx, Clethrionomys, and Lemmus-Synaptomys. In addition, biochemical data support the view that various lineages of the large genus Microtus share a recent common ancestor (1.6-2 106 years). One case of disagreement concerns the phylogenetic position of the snow vole, Chionomys nivalis. Whereas the fossil record seems to indicate that separation of Chionomys from Microtus occurred less than 1 106 years ago, biochemical data suggest that isolation of Chionomys took place more than 2.4 106 years ago. Disagreement also exists with respect to the phylogeny of North American species of the genus Microtus. Despite suspected polyphyletism of the subgenera Pitymys and Pedomys, the analyzed species form a homogeneous cluster with respect to protein electrophoresis.