Inclusive fitness and reproductive strategies in dwarf mongooses

Abstract

Dwarf mongooses (Helogale parvula) are small, communally breeding carnivores found in woodland and tree-savanna throughout Africa. Within a pack, socially subordinate mongooses do not normally breed, yet they invariably participate in all aspects of parental care. The primary alternative to tolerating reproductive suppression is dispersal, which shortens the wait for dominance and breeding. Here, we calculate the annual inclusive fitness payoffs to the dispersing and nondispersing strategies for males and females of ages one to seven, using data from a 14-year study in Serengeti National Park, Tanzania. Factors with effects on inclusive fitness included relatedness to pack mates before and after dispersal, the effect of help on recipients' reproductive success, the probability of dispersing successfully, the probability of attaining dominance, and reproductive success after attaining dominance. All of these factors differed between male and female dwarf mongooses. We compared the contributions of direct and indirect fitness to the total fitness of mongooses pursuing each of the strategies, across a range 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 indirect fitness was substantial for young (< 2 years old) dispersers. For nondispersers of both sexes, indirect fitness was the major component of total fitness among young mongooses (up to 2 or 3 years), but direct fitness was the major component among older mongooses. By comparing the inclusive fitness payoffs for the two strategies, we determined the range of ages at which dispersal should be favored for each sex. These comparisons correctly predicted that males should be more dispersive than females at all ages, and that males should disperse over a broader range of ages.

The evolution of female social relationships in nonhuman primates

“…Usually suppression is complete; when subordinates breed, they risk infanticide by dominants (Digby 1994), and probably have little chance of raising o spring successfully even without infanticide. Callitrichid maternal energetics and mating systems ®nd parallels among communally breeding carnivores (e.g., dwarf mongoose: Creel and Waser 1994;reviewed in Creel and Creel 1991). They are unusual for primates, but partial reproductive suppression, coupled with targeted aggression, may be common in RN species (above; cf.…”

Cooperation among unrelated individuals: the ant foundress case

“…This makes those exceptional cases where cooperators are unrelated particularly interesting, because these groups should confer direct benefits, or a probability of direct benefits, on all their members, a condition which should have a great impact on the nature of their cooperation. Unrelated group members have been reported in kingfishers 2 , manakins 3 , mongooses 4 , halictine bees 5 and ant foundresses 6,7 .…”

The Right Tools for the Job: Cooperative Breeding Theory and an Evaluation of the Methodological Approaches to Understanding the Evolution and Maintenance of Sociality

“…However, the authors believe that estimates of the survival rate of emigrants and philopatric animals could be calculated from existing census data and behavioral observations to estimate such a parameter. Waser et al (1994) demonstrated the effectiveness of this approach using data from a number of observational studies on dwarf mongooses, Helogale parvula (Rood, 1983(Rood, , 1987(Rood, , 1990Creel and Waser, 1994). This study showed that in this species, older and more experienced individuals had greater dispersal success.…”