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Age at maturity in wild baboons: genetic, environmental and demographic influences

Authors

  • M. J. E. CHARPENTIER,

    1. Department of Biology, Duke University, PO Box 90338, Durham, NC 27708, USA,
    2. Centre d’Ecologie Fonctionnelle et Evolutive, Unite Mixte de Recherche 5175, Centre National de la Recherche Scientifique, 1919 Route de Mende, 34293 Montpellier Cedex 5, France,
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  • J. TUNG,

    1. Department of Biology, Duke University, PO Box 90338, Durham, NC 27708, USA,
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  • J. ALTMANN,

    1. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08540, USA,
    2. Institute of Primate Research, National Museums of Kenya, PO Box 24481, Nairobi, Kenya
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  • S. C. ALBERTS

    1. Department of Biology, Duke University, PO Box 90338, Durham, NC 27708, USA,
    2. Institute of Primate Research, National Museums of Kenya, PO Box 24481, Nairobi, Kenya
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Marie Charpentier, Department of Biology, Duke University, PO Box 90338, Durham, NC 27708, USA. Fax: +01 919 660 7293; E-mail: mariecharp@yahoo.fr

Abstract

The timing of early life-history events, such as sexual maturation and first reproduction, can greatly influence variation in individual fitness. In this study, we analysed possible sources of variation underlying different measures of age at social and physical maturation in wild baboons in the Amboseli basin, Kenya. The Amboseli baboons are a natural population primarily comprised of yellow baboons (Papio cynocephalus) that occasionally hybridize with anubis baboons (Papio anubis) from outside the basin. We found that males and females differed in the extent to which various factors influenced their maturation. Surprisingly, we found that male maturation was most strongly related to the proportion of anubis ancestry revealed by their microsatellite genotypes: hybrid males matured earlier than yellow males. In contrast, although hybrid females reached menarche slightly earlier than yellow females, maternal rank and the presence of maternal relatives had the largest effects on female maturation, followed by more modest effects of group size and rainfall. Our results indicate that a complex combination of demographic, genetic, environmental, and maternal effects contribute to variation in the timing of these life-history milestones.

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