New karyotypes of the common shrew Sorex araneus (Lipotyphla, Mammalia) at the northern periphery of the species range in European Russia

Abstract

The karyotypic diversity of the common shrew was examined in a poorly studied area of northeastern European Russia between the estuary of the Pechora River and the North Ural Mountains. The karyotypes that belonged to the Serov chromosomal race were found at 500 km to the north from the previously known race range limit. In addition, three new homozygous karyotypic variants were detected in the vicinities of the towns of Inta and Naryan-Mar (near and above the Arctic Circle, respectively). An individual with the diagnostic metacentrics go, hn, im, kq, and pr—termed the “Inta” variant—could have originated from a single whole-arm reciprocal translocation (WART) from the karyotype of the Sok race. This variant corresponds to the predicted karyotype that links the Petchora and Sok races. The second variant had the metacentrics go, hn, im, kr, and pq (Naryan-Mar) and could have arisen from the “Inta” variant by a single WART. An unusual karyotype that was found on the left bank of the Pechora River was determined to be a recombinant that resulted from natural hybridization between the Petchora race and new “Naryan-Mar” variant. Thus, we have determined the origin of new karyotypic variants in a small local hybrid population.