The Edible Dormouse (Glis glis, Gliridae, Rodentia) in the Periphery of Its Distribution Range: Body Size and Life History Parameters

Resumo

The body size, longevity, growth rate, and the intensity of breeding in a peripheral population of the edible dormouse from the Zhiguli Mountains are analyzed from the standpoint of life cycle theory. A breeding peculiarity of the species lies in periodically repeated years of reproductive failure, i.e., the total absence of young, seen throughout the species range. In reproductively successful years, anticipatory reproduction is observed, when the birth of posterity precedes a period of maximum food abundance. In the optimum of the distribution range, in Central and Western Europe, the mechanism of reproductive control in unfavorable years is based on the suppressing of the male reproductive activity at the beginning of the active season. In the Zhiguli population, natality regulation is rooted in mass resorption of embryos in the vast majority of females. In that population, the body size and weight are the minimum, while the difference from individuals from other populations studied may reach three times. The peculiarities of the edible dormouse biology in the peripheral population are related to the life cycle parameters. In contrast to the Central European populations, reproduction in the Zhiguli occurs every year, but in pregnant females, the death of embryos is observed in lean years. In males of that population, which are reproductively active every year, no significant costs of reproduction related to weight loss have been identified. The lower growth rate in comparison with more western European populations is shown in four age groups conventionally distinguishable based on morphometric parameters. In yearling males whose growth is not yet finished, the onset of the mating period depends on the body mass. Typically, the lifespan in the study population does not exceed four years, this being much shorter than in other populations where it lasts seven to nine years.