No evidence of inbreeding avoidance or inbreeding depression in a social carnivore

Dispersal by young mammals away from their natal site is generally thought to reduce inbreeding, with its attendant negative fitness consequences. Genetic data from the dwarf mongoose, a pack-living carnivore common in African savannas, indicate that there are exceptions to this generalization. In dwarf mongoose populations in the Serengeti National Park, Tanzania, breeding pairs are commonly related, and close inbreeding has no measurable effect on offspring production or adult survival. Inbreeding occurs because average relatedness among potential mates within a pack is high, because mating patterns within the pack are random with respect to the relatedness of mates, and because dispersal does little to decrease the relatedness among mates. Young females are more likely to leave a pack when the dominant male is a close relative but are relatively infrequent dispersers. Young males emigrate at random with respect to the relatedness of the dominant female and tend to disperse to packs that contain genetically similar individuals.