A contrasted pattern of chromosome evolution in two genera of lemmings, Lemmus and Dicrostonyx (Mammalia, Rodentia)

Abstract

Lemmings of the genus Lemmus display a very moderate degree of karyotype diversity. In L. lemmus from the Kola Peninsula, L. sibiricus sibiricus from the Pechora inlet coast and the Laptev Sea coast, L.s. portenkoi from the Vrangell Island and L. amurensis from Southern Yakutia the gross chromosome morphology and C-banding pattern proved to be identical (2n = 50, NF = 50). The chromosome set of L.s. chrysogaster (the Chukotka Peninsula) consists of 23 pairs of acrocentrics and 2 pairs of subtelocentrics (2n = 50, NF = 54), and so it is identical to the karyotype of North American Lemmus. As to spatial structure of populations, population dynamics, degree of inbreeding and uniformity of habitats throughout the area, Lemmus is basically similar to the lemmings of another genus, Dicrostonyx. In the latter, however, an extensive chromosome diversity has been found. Therefore, the ecological and population characteristics mentioned above are suggested not to be essential for the rate of chromosome evolution in lemmings.