INCLUSIVE FITNESS AND REPRODUCTIVE STRATEGIES IN DWARF MONGOOSES

Dwarf mongooses (Helogale parvula) are small, communally breeding carn ivores found in woodland and tree-savanna throughout Africa. Within a pack, socially subordinate mongooses do not normally breed, yet they i nvariably participate in all aspects of parental care. The primary alt ernative to tolerating reproductive suppression is dispersal, which sh ortens the wait for dominance and breeding. Here, we calculate the ann ual inclusive fitness payoffs to the dispersing and nondispersing stra tegies for males and females of ages one to seven, using data from a 1 4-year study in Serengeti National Park, Tanzania. Factors with effect s on inclusive fitness included relatedness to pack mates before and a fter dispersal, the effect of help on recipients' reproductive success , the probability of dispersing successfully, the probability of attai ning dominance, and reproductive success after attaining dominance. Al l of these factors differed between male and female dwarf mongooses. W e compared the contributions of direct and indirect fitness to the tot al fitness of mongooses pursuing each of the strategies, across a rang e of ages. In our population, dispersal and nondispersal both yielded direct and indirect payoffs at most ages. For dispersers of both sexes , direct fitness was the primary component of total fitness but indire ct fitness was substantial for young (less-than-or-equal-to 2 years ol d) dispersers. For nondispersers of both sexes, indirect fitness was t he major component of total fitness among young mongooses (up to 2 or 3 years), but direct fitness was the major component among older mongo oses. By comparing the inclusive fitness payoffs for the two strategie s, we determined the range of ages at which dispersal should be favore d for each sex. These comparisons correctly predicted that males shoul d be more dispersive than females at all ages, and that males should d isperse over a broader range of ages.