Signatures of Adaptation in Mitochondrial Genomes of Palearctic Subterranean Voles (Arvicolinae, Rodentia).

This study evaluates signatures of selection in the evolution of the mitochondrial DNA of voles, subfamily Arvicolinae, during the colonization of subterranean environments. The comparative sequence analysis of mitochondrial protein-coding genes of eight subterranean vole species (, three species of the genus : , and , two species of the genus : and , and ) and their closest aboveground relatives was applied using codon-substitution models. The highest number of selection signatures was detected in genes and The relaxation of selection was observed in most mitochondrial DNA protein-coding genes for subterranean species. The largest amount of relaxed genes is discovered in mole voles (genus ). The number of selection signatures was found to be independent of the evolutionary age of the lineage but fits the degree of specialization to the subterranean niche. The common trends of selective pressures were observed among the evolutionary ancient and highly specialized subterranean rodent families and phylogenetically young lineages of voles. It suggests that the signatures of adaptation in individual mitochondrial protein-coding genes associated with the colonization of the subterranean niche may appear within a rather short evolutionary timespan.