Patterns of parasitism in the cooperatively breeding meerkat: a cost of dominance for females

Within animal societies, demographic and social factors, as well as the different reproductive efforts of group members, may influence individual patterns of reproductive success and parasitism. In mammals, such relationships have been studied primarily in male-dominant species. To better understand these linkages in other social systems, we studied a female-dominant cooperative breeder, the meerkat (Suricata suricatta). This species is characterized by intense intrasexual competition and extreme reproductive skew in both sexes. Within adults, we examined heterogeneities in infection by 6 species of endoparasites in relation to host factors (e.g., weight, age, social status, sex, and group size). We explored potential trade-offs between reproduction and parasitism in dominant and subordinate animals of both sexes. Whereas weight and age were predictive of a few parasite taxa, social status or sex predicted parasite species richness and patterns of infection for the majority of parasites examined. Moreover, a significant interaction between sex and status for 2 nematode taxa revealed that dominant females were the most at risk of infection. Lastly, a positive relationship between group size and parasitism was evident in females only. In sum, compared with subordinates, dominant meerkats may experience increased exposure to directly transmitted parasites. Coupled with hormone-mediated immunosuppression, the increased susceptibility of dominant females may reflect energy allocation for preferentially maintaining dominance and breeding status over parasite defense. In species in which female intrasexual competition is intense, this trade-off between reproduction and health may be more pronounced in females than in males.