Systematics, Historical Biogeography, and Evolution of the Genus Sorex

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Abstract
Systematic relationships among 26 Palearctic and Nearctic species of Sorex were examined using allozyme electrophoresis. The genus has been classified into three subgenera, Sorex, Otisorex, and Microsorex. Cladistic, phenetic, and distance-Wagner analyses of 26 loci indicate that the subgenus Microsorex should be included within Otisorex, and the subgenus Sorex should be divided into two subgenera. The new subgenus is the sister taxon to Otisorex and Sorex. Comparing results of electrophoretic analyses to the fossil record provides a divergence time from ancestral stock of early Pliocene for the new subgenus, and a time of late Pliocene for the Otisorex-Sorex divergence. Fossil evidence suggests that the S. fumeus, S. cinereus, S. vagrans, S. palustris, and S. hoyi lineages were established in the early Pleistocene. Results of allozymic analyses support the fossil data, and suggest that the divergence from the basic Otisorex stock into these five lineages occurred over a short period of time.