Genetic relationships and differentiation in ground squirrels Marmotinae Pocock, 1923 (Rodentia, Sciuridae) from Palearctics

Genetic distances between eight species of sousliks (Spermophilus) and five species of marmots (Marmota) were estimated on the basis of 39 biochemical loci. All taxa were shown to be genetically discrete. The genetic differen tiation was minimal (Pfd = 11.3) between parapatric species of Palearctic s ousliks of the suslicus-pygmaeus group and Marmota species (Pfd = 11.9), in termediate (Pfd = 34.7) between allopatric sousliks species, and maximal (P fd = 56.7) between representatives of different genera. The following trend s were revealed in the geographic differentiation of the genus Spermophilus : (1) genetic similarity was associated with the geographic distance; (2) t he eastern and western Palearctic phyla were markedly different genetically ; (3) the eastern Palearctic forms exhibited higher differentiation than th e western ones. The revealed speciation pattern is consistent with the gene ral trend of temporal differentiation in Palearctic phyla and confirms the periodic speciation mode in the Palearctics.