Nucleolar organizing regions (NORs) of common vole chromosomes as nuclear markers of genome differentiation in data from a hybrid zone of two karyoforms, arvalis and obscurus

Abstract

Contrasting chromosome location of nucleolar organizing regions (NORs), a poorly studied differentiating feature of two karyoforms of the 46-chromosome common voles, arvalis and obscurus, is demonstrated in the heterozygous karyotype of a natural hybrid from the arvalis/obscurus contact zone in European Russia. It was deduced from the karyotype analysis that the obscurus form was parental in this case and the arvalis form was defined as maternal via the markers of the mitochondrial genome. The similarities in the levels of chromosome polytypy and the lineage differentiation of the arvalis/obscurus and obscurus mitochondrial genomes according to the new and earlier published data is noticeable.