Comparative karyology of Palearctic marmots (Marmota, Sciuridae, Rodentia)

Abstract

G- and nucleolar organizer regions-banded chromosomal sets of some Palearctic Marmota species were examined. Based on G-banding chromosomes homology in different species karyotypes was investigated. A schema of Palearctic marmots' karyotype evolution is proposed. All of the studied marmots karyotypes likely originated from one ancestral karyotype with 2n=38, NF=70 that was similar to the M. caudata and M. menzbieri ones. A 38-chromosomal karyotype within the Palearctic marmots group clearly demonstrates considerable stability. “Good” morphological species, M. caudata, M. menzbieri, M. himalayana, have similar karyotypes, and other species with 2n=38 carry single minor rearrangements of chromosomes. Only two species karyotypes, M. camtschatica and M. kastschenkoi, originated from the prominent chromosomal reorganizations. It may be explained by juvenility of the group or by high stability of ancestral 38-chromosomal karyotype. The one submetacentric pair of chromosomes participates in both of the most important rearrangements in Marmota history that may indicate some instability of this part of marmot karyotype. A combination of karyological and morphological data supports the distinction of all recognized Palearctic species of marmots adding to the list a new one, M. kastschenkoi. A segregation of bobak and camtschatica species group is supported.