Kartavtseva I.V., Pozdnyakov A.A., Stepanova A.I., Sheremetyeva I.N., Pavlenko M.V.
Zoologicheskiy zhurnal 2025; 104(9): 85-104
The Evoron vole is a narrow-range species known from three isolated populations in three mountain basins in the south of the Russian Far East. The species has multiple chromosomal polymorphism found in two chromosomal races: "evoron" and "argi". Morphotypic variations in the masticatory surface of 357 third upper molars (M3) belonging to voles from six natural populations (Evoron-Chukchagir Lowland - 2, Verkhne-Bureinskaya Depression - 1, Verkhne-Zeya Basin - 2, upper reaches of the Amgun River - 1), as well as three lines of laboratory breeds of chromosomal races were analyzed. Traditional and complex methods were used to describe morphotypes. Sixteen morphotypes were described using the complex method, ten of which were not previously described for the species. Each sample was characterized by its own set of main morphotypes. The number of reserve morphotypes in natural populations was less (from 0 to 5) than in laboratory lines (from 5 to 10). In individuals of the chromosomal race "evoron" (animals from the Evoron-Chukchagir Lowland), the complex method revealed both the presence of M3 morphotypes with fused first two prisms and lower morphotypic variability compared to the chromosomal race "argi" (animals from the Verkhne-Bureinskaya Depression and the Verkhne-Zeya Basin). The chromosomal races were also shown to differ in the number of morphotypes (M3), their combinations, asymmetry index, and the frequency of combinations. Comparing the M3 complexity coefficients of two groups of all samples taken at different times in the 1970s and 2000s from three intermountain basins revealed a chronographic trend of an increased proportion of simple teeth in the forty-year long interval of studies.
