[Genetic-ecology monitoring of cycling populations of water voles (Arvicola terrestris L.) in the south of Western Siberia].

Long-term studies on the role of the structural and functional organization of a population in reproduction control showed that the optimum level of reproduction is maintained via a complex of ethological, physiological, and genetic mechanisms. The coat color genes have a pleiotropic effect on the reproductive capacity of females and the potential for social dominance in males. The relative reproductive success of brown water voles is greater when the population size increases, whereas dark-brown individuals gain the advantage at peaks of population size. At the peak followed by a decrease in abundance, dark brown males usually held higher social ranks in the experimental groups. The results of field and laboratory experiments showed that high-ranking males gain reproductive advantage. Changes in the genetic structure in the course of population cycle depend on relative differences in fitness demonstrated by animals of different coat color under conditions of changing population size. The fact that females actively choose their mates is important for differentiation of males with respect to their adaptive value, prevention of inbreeding, and the maintenance of heterogeneity of populations as the basis of their stability.