Kinship structure and mating system in a solitary subterranean rodent, the silvery mole-rat

The African mole-rats (Bathyergidae, Rodentia) are subterranean rodents that have evolved a wide range of social organisations varying from solitary to eusocial. Due to some unusual features of their breeding and social systems, much attention has been focused on social species, with solitary species being virtually ignored. Here, we present the first genetic study on the mating system of any solitary mole-rats, the silvery mole-rat (Heliophobius argenteocinereus) - a species which is assumed to be monogamous. Microsatellite markers were used to analyse the mating system and the kinship structure in populations in southern Malawi. Isolation by distance between individuals was apparent in two studied populations, but not in the third, probably, as a result of barriers limiting dispersal in the latter population. Polygyny was found to be a mating system in this population, where a strongly female-biased adult sex ratio was present. In this case, large distances between the burrow systems of mating partners exclude the possibility of belowground searching for mates, suggesting that the males might seek females aboveground. Interestingly, among analysed litters from various localities, one multiple-sired litter was found. Therefore, the results suggest that the mating system in potentially monogamous solitary subterranean rodents may be much more variable than expected and can differ among populations.