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Kuruman, South Africa

Smyth K.N.,Duke University | Smyth K.N.,Kalahari Research Trust | Drea C.M.,Duke University | Drea C.M.,Kalahari Research Trust
Behavioral Ecology | Year: 2016

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. © 2015 The Author 2015. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


delBarco-Trillo J.,Kalahari Research Trust | delBarco-Trillo J.,Duke University | delBarco-Trillo J.,Liverpool John Moores University | Greene L.K.,Kalahari Research Trust | And 16 more authors.
Hormones and Behavior | Year: 2016

In male vertebrates, androgens are inextricably linked to reproduction, social dominance, and aggression, often at the cost of paternal investment or prosociality. Testosterone is invoked to explain rank-related reproductive differences, but its role within a status class, particularly among subordinates, is underappreciated. Recent evidence, especially for monogamous and cooperatively breeding species, suggests broader androgenic mediation of adult social interaction. We explored the actions of androgens in subordinate, male members of a cooperatively breeding species, the meerkat (. Suricata suricatta). Although male meerkats show no rank-related testosterone differences, subordinate helpers rarely reproduce. We blocked androgen receptors, in the field, by treating subordinate males with the antiandrogen, flutamide. We monitored androgen concentrations (via baseline serum and time-sequential fecal sampling) and recorded behavior within their groups (via focal observation). Relative to controls, flutamide-treated animals initiated less and received more high-intensity aggression (biting, threatening, feeding competition), engaged in more prosocial behavior (social sniffing, grooming, huddling), and less frequently initiated play or assumed a 'dominant' role during play, revealing significant androgenic effects across a broad range of social behavior. By contrast, guarding or vigilance and measures of olfactory and vocal communication in subordinate males appeared unaffected by flutamide treatment. Thus, androgens in male meerkat helpers are aligned with the traditional trade-off between promoting reproductive and aggressive behavior at a cost to affiliation. Our findings, based on rare endocrine manipulation in wild mammals, show a more pervasive role for androgens in adult social behavior than is often recognized, with possible relevance for understanding tradeoffs in cooperative systems. © 2015 Elsevier Inc.

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