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Patterns of interventions and the effect of coalitions and sociality on male fitness

Authors

  • LARS KULIK,

    1. Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
    2. Institute for Biology, University of Leipzig, Talstrasse 32, 0341 Leipzig, Germany
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  • LAURA MUNIZ,

    1. Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
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  • ROGER MUNDRY,

    1. Max-Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
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  • ANJA WIDDIG

    1. Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
    2. Institute for Biology, University of Leipzig, Talstrasse 32, 0341 Leipzig, Germany
    3. Caribbean Primate Research Center, PO Box 906, Punta Santiago, PR 00741, USA
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Anja Widdig, Fax: +49 341 3550 299; E-mail: anja.widdig@eva.mpg.de

Abstract

In group living animals, especially among primates, there is consistent evidence that high-ranking males gain a higher reproductive output than low-ranking males. Primate studies have shown that male coalitions and sociality can impact male fitness; however, it remains unclear whether males could potentially increase their fitness by preferentially supporting and socializing with females. Here we investigate patterns of male interventions and the effect of coalitions and sociality on male fitness in rhesus macaques (Macaca mulatta) with particular focus on male–female interactions. We combined behavioural observations collected on Cayo Santiago with genetic data analysed for male reproductive output and relatedness. Our results revealed that the ten top-ranking males provided the majority of all male support observed. In contrast to other primates, male rhesus macaques mainly formed all-down coalitions suggesting that coalitions are less likely used to enhance male dominance. Males supporting females during and before their likely conception were not more likely to fertilize those females. We also found no evidence that males preferably support their offspring or other close kin. Interestingly, the most important predictor of male support was sociality, since opponents sharing a higher sociality index with a given male were more likely to be supported. Furthermore, a high sociality index of a given male–female dyad resulted in a higher probability of paternity. Overall, our results strengthen the evidence that sociality affects fitness in male primates, but also suggest that in species in which males queue for dominance, it is less likely that males derive fitness benefits from coalitions.

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