Age-related dynamics of reproductive activity and physical conditions in Cricetidae of different ecological speciation (Rodentia)

Abstract

To understand the evolutionary preconditions of extended longevity, one can compare the key life-history events and age related changes in body conditions in related species with different ecological speciation. Cricetid rodents possessing a wide spectrum of adaptive forms with different life history strategies are an excellent model for this purpose. We compared median and maximum longevity, life expectancy, temporal distribution of reproductive efforts, and age related dynamic of several physical condition indexes: body mass, muscle strength, locomotor activity and frequency of vertical postures in open field tests in five species of this family. Studied species vary both in maximum (from three years in steppe lemmings (Lagurus lagurus) to more than six years in mole voles (Ellobius talpinus) and rock voles (Alticola strelzovi) and median longevity (from less than one year in Lagurus lagurus to 2.8 years in rock vole Alticola tuvinicus). Both species with high maximum longevity – Ellobius talpinus and Alticola strelzovi face chronic hypoxia in their native environment. The total amount of litters born varied from three in A. strelzovi to 13 in Phodopus sungorus. Species under study also differed in age-related dynamics of physical conditions. Among the studied species, the subterranean E. talpinus has the highest maximum longevity with relatively long duration of reproductive period and only weak age-related deterioration in body conditions, i.e. shares many aspects of the life history strategy of such a specialized group as the Bathyergidae family.