One more Microtus species with asynaptic sex chromosomes

Abstract

Arvicoline voles are known as a karyotypically extremely polymorphic group in which the genus Microtus leads with the highest rate of karyotype change. A member of this genus, the European pine vole Microtus subterraneus (de Selys-Longchamps, 1836), is widely distributed in Europe and parts of Asia. There are two cytotypes differing in diploid chromosome number, 2n=54 and 52, each showing different chromosomal polymorphisms. At two localities in southeastern Serbia, Mt. Jastrebac and Vlasina, we found the 2n=52 cytotype. Meiotic preparations from males revealed the presence of asynaptic sex chromosomes. Although asynaptic sex chromosomes are frequent in Microtus, this is the first finding for M. subterraneus. From summarized data it appears that two-thirds of the studied species, mainly from Microtus and Terricola subgenera, possess asynaptic sex chromosomes.