1Department of Anthropology, University of Texas at Austin, 2Wisconsin National Primate Research Center, University of Wisconsin-Madison
April 18, 2020 , Platinum Ballroom
Female fertility varies according to reproductive hormone concentrations, but females may be sexually receptive during different reproductive stages. Among many primate species, females have been observed engaging in post-conceptive copulations, which are sometimes discussed as a strategy to confuse paternity and reduce the risk of infanticide. Here, we describe post-conceptive mating behaviors in a population of wild woolly monkeys (Lagothrix lagotricha poeppigii) at the Tiputini Biodiversity Station in Amazonian Ecuador. Woolly monkeys live in multimale-multifemale social groups that are characterized by a promiscuous mating system with no clear dominance hierarchies among males. Genetic evidence suggests that paternity skew may be high; nonetheless, mating skew is minimal, and all males display affiliative behavior towards young infants. We investigated the temporal relationship between copulations and fecal progesterone (PdG) and estrogen (E1G) metabolites from receptive females in 2017 who gave birth to offspring in 2018 (n = 4). Estimated conceptions were confirmed with endocrine profiles that showed a significant increase in PdG and E1G (W = 0, p < 0.05) after conception. All females were seen copulating both before and after they conceived, with higher rates of copulations post conception (W = 1, p < 0.05). The last mating event recorded for these females averaged 35±22 days after conception. Our results indicate that post-conceptive mating is not restricted to primate species with high levels of infanticide and, in woolly monkeys, might be used by females to confuse paternity among different males who may provide certain social benefits to a female and her offspring.
Funded by NSF BCS-1540403, NSF BCS-1638822, the L.S.B. Leakey Foundation, and the University of Texas at Austin.