Main Directions and Factors Determining the Variability of CYTB Amino Acid Sequences in Mountain Voles (Alticola, Rodentia, and Arvicolinae)

A statistical analysis of variability in the amino acid composition of the mitochondrial CYTB protein from Asian mountain voles (genus Alticola) has been carried out. The sequences used in the study (N = 36; 380 amino acid residues), as well as information about their geographic origin, have been taken from GenBank. For each sequence, amino acid frequencies have been calculated, as has the matrix of squared Euclidean distances between them, followed by the calculation of principal components (PCs) by the principal coordinate method. Within the space of the first two PCs (Σλ = 76.89%), all sequences are grouped according to their species membership and form the East Siberian (A. strelzowi, A. olchonensis, A. semicanus, and A. tuvinicus), southern (A. stracheyi, A. argentatus, A. albicaudus, A. stoliczkanus, and A. barakshin), and northeastern (A. lemminus and A. macrotis) groups. For the PC1 direction, a change in the frequencies of Met, Gly, Ile → Ala, Thr occurs; the component strongly correlates with a large subset of AA indices (N = 362 at p < 0.01, with allowance for multiple comparisons according to Bonferroni) and the average evolutionary rank of CYTB sequences. For the PC2 direction, there is a change in the Val and Phe → Leu frequencies. This direction significantly correlates with the latitude (r = 752; p < 0.001) and altitude (r = –717; p < 0.01) of the vole habitats, as well as with 21 climatic variables and 54 AA indices.