For the first time, different lifetime was established in representatives of three colour morphs (brown, bicolor, black) in 10 populations of the Mole Vole of the Volga region, the Urals and the Trans-Urals. With the longest life span of the species – 5 years, numerically dominant morphs in the population are able to live 1–4 years longer than the accompanying ones. Spearman’s correlation coefficient between the longest life span of morphs and their proportion in the population was Rsp = 0.81. A number of morphofunctional features of colour morphs have been identified. The results obtained have general biological significance, confirming the hypothesis of adaptive polymorphism, and allowing us to evaluate the evolutionary and ecological mechanisms of the formation of selective advantages of morphs (as probable ecomorphs), using them as a natural model of the initial stage of sympatric formation in different parts of the range.