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Loss of oestrus, concealed ovulation and paternity confusion in free-ranging Hanuman langurs

Michael Hestermann, Thomas Ziegler, Carel P. van Schaik, Kristin Launhardt, Paul Winkler, J. Keith Hodges

Abstract

Ovarian cycles in catarrhine primates are uniquely characterized by prolonged periods of sexual activity in which the timings of ovulation and copulation do not necessarily correspond. According to current hypotheses of primate social evolution, extended sexuality in multi-male groups might represent part of a female strategy to confuse paternity in order to reduce the risk of infanticide by males. We test this hypothesis by examining mating behaviour in relation to timing of ovulation and paternity outcome in a multi-male group of free-living Hanuman langurs. Using faecal progestogen measurements, we first document that female langurs have extended receptive periods in which the timing of ovulation is highly variable. Next, we demonstrate the capacity for paternity confusion by showing that ovulation is concealed from males and that copulations progressively decline throughout the receptive phase. Finally, we demonstrate multiple paternity, and show that despite a high degree of monopolization of receptive females by the dominant male, non-dominant males father a substantial proportion of offspring. We believe that this is the first direct evidence that extended periods of sexual activity in catarrhine primates may have evolved as a female strategy to confuse paternity.

Footnotes

  • * Author for correspondence (mheiste{at}gwdg.de).

  • Present Address: Abteilung Forschung, Georg-August-Universität, Goßlerstrasse 9,37073 Göttingen, Germany.

  • Present Address: Brandgasse 12,35390 Gießen, Germany.

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