Ecological and evolutionary preconditions of extended longevity in subterranean rodents

Abstract

According to the evolutionary theory of aging, a low level of extrinsic mortality, i.e., a low probability of the early death of animals, promotes an increase in the maximum lifespan. The subterranean rodents that dwell in well-protected environment, live longer than the terrestrial species. In the social African mole rat species with reproductive division of labor, the mortality of workers in wildlife is considerably higher than in breeders, while significant interspecific differences in the lifespan patterns may emerge in captivity. The lifespans of different castes in the family groups of the naked mole rat (Heterocephalus glaber) in captivity are almost equal. However, the breeders of another social species, the Ansell’s mole rat (Fukomys anselli), on the average live twice as long as workers. A possible explanation for the observed differences can be associated with the species specificity in their social organization, first and foremost, the mechanisms responsible for reproductive skew. A unique feature of the naked mole rat is tolerance for incest, which theoretically equalizes the chances of all individuals to be a breeder within the native family. In other social mole rat species, which avoids inbreeding, the only possibility for reproduction is dispersal. In captivity, the inability to leave the maternal family may cause the suppression of homeostatic functions responsible for longevity.