Allozyme differentiation in five species of North American shrews (Soricidae: Mammalia)

Abstract

Starch gel electrophoresis was used to investigate patterns of genetic variation in five species of shrews from southern Illinois, and western Kentucky and Tennessee. Four of the five species occur sympatrically. Twenty-eight presumptive loci were examined in the following species: pygmy shrew Sorex hoyi Baird, southeastern shrew Sorex longirostris, northern short-tailed shrew Blarina brevicauda, southern short-tailed shrew Blarina carolinensis, and least shrew Cryptotis parva. Of the 28 loci, 11 were monomorphic for the same allele in all species. Only one locus ( Mpi) was diagnostic, with a different allele for each species. At two other loci ( Est and PepD) the two species of Blarina also demonstrated significant differences. These three loci could be used to distinguish the two morphologically very similar species of Blarina. The mean heterozygosity values for B. brevicauda and S. hoyi were higher than previously reported. Levels of heterozygosity did not show a correlation with known degree of habitat specialization in the five species. Genetic distance analysis demonstrated greater genetic similarity between the two Blarina species than the two Sorex species. A dendrogram produced from a genetic distance matrix is consistent with current views of soricid phylogeny.