[Revision of the Taxonomic Position of the Olkhon Mountain Vole (Rodentia, Cricetidae)].

An analysis of the phylogenetic position of the Olkhon mountain vole (Alticolaolchonensis Litvinov 1960) using the sequences of four nuclear (BRCA, GHR, LCAT, and IRBP) and one mitochondrial (cyt. b) genes was undertaken. It was noted that, until recently, multiple studies of the systematic position of this vole had been based exclusively on morphological data, while the major taxonomic traits contained contradictory information regarding both the subgeneric status of this species and its genus. It was established that the molecular data and morphology data allow us to attribute the Lake Baikal vole unambiguously to the nominative subgenus Alticola instead of Aschizomys.

[Supraspecies relationships in the subfamily (Rodentia, Cricetidae, Arvicolinae): unexpexted result of nuclear genes analysis].

Phylogenetic analysis of supraspecies relationships in one of the most young and species rich group of myomorph rodents - subfamily Arvicolinae was carried out on the base of two nuclear genes. Results have shown that mole-voles - Ellobiusini, steppe voles - (Lagurini) and grey voles (Arvicolini) are sister groups. This divergence is the most late, third wave of radiation within the family. The sister clade to this group is the tribe of red-back voles - Myodini (=Clethrionomini) - "second radiation". The order of divergence for earliest radiation remains still unresolved (Ondatrini, Prometheomyini, Dicrostonychini, Lemmini). New data on the close relationships of mole voles, grey voles and steppe voles are unexpected one and contradict to the conventional views. The latter ideas on the significant ancientry and separation of Ellobiusini from all other voles is based on extreme simplicity of their rooted molars and very peculiar structure of the skull and postcranial skeleton. However, many of these characters most likely indicate on significant degree of adaptation to the subterranean life and have no phylogenetic signal.

[Genetic variation and phylogeography of the bank vole (Clethrionomys glareolus, Arvicolinae, Rodentia) in Russia with special reference to the introgression of the mtDNA of a closely related species, red-backed vole (C. rutilus)].

Totally, 294 bank voles (Clethrionomys glareolus) and 18 red-backed voles (C. rutilus) from 62 sites of European Russia were studied. Incomplete sequences (967 bp) of the mitochondrial cytochrome b gene were determined for 93 C. glareolus individuals from 56 sites and 18 C. rutilus individuals from the same habitats. Analysis of the cytochrome b gene variation has demonstrated that practically the entire European part of Russia, Ural, and a considerable part of Western Europe are inhabited by bank voles of the same phylogroup, displaying an extremely low genetic differentiation. Our data suggest that C. glareolus very rapidly colonized over the presently occupied territory in the post-Pleistocene period from no more than two (central European and western European) refugia for ancestral populations with a small efficient size. PCR typing of the mitochondrial cytochrome b gene allowed us to assess the scale of mtDNA introgression from a closely related species, C. rutilus, and to outline the geographical zone of this introgression. Comparison with the red-backed vole haplotypes in the habitats shared by both species favors the hypothesis of an ancient hybridization event (mid-Holocene) and a subsequent introgression. These results suggest that the hybridization took place in the southern and middle Pre-Ural region.

[Evaluation of the gene encoding translation termination factor eRF3 as a possible phylogenetic marker].

We have tested if a part of nuclear gene GSPT2 encoding N and M domains of translation termination factor eRF3b could be applied as a new molecular marker, using order Rodentia as a model group. The proposed fragment cannot be used as a phylogenetic marker at intrageneric level because of low variability within families and impossibility to resolve relationships in family Cricetidae. However, this part of GSPT2 gene allows to divide higher taxa reliably. Phylogenetic relationships between families established using the proposed molecular marker mainly correspond with contemporary conceptions. The new marker indicates close relationship of genus Acomys with family Gerbillidae in agreement with other molecular data but opposing to morphological ones. Thus the part of gene GSPT2 encoding N and M domains of eRF3b protein can be applied as an adequate phylogenetic marker in placental mammals at family and higher taxonomic levels. Also it can be used while solving controversial questions of phylogeny and taxonomy.