The strategic use of sex in wild female western gorillas

Doran-Sheehy, Diane M.; Fern�ndez, David; Borries, Carola

Abstract

Human females, unlike most mammals, are sexually active outside of fertile periods. This decoupling of sexual behavior from its conceptive function has had an enormous impact on human social relationships, and yet we know little about why there was selection for nonconceptive mating. Here we examine one form of nonconceptive mating, the mating that occurs during pregnancy or post-conceptive (PC) mating, in wild western gorillas (Gorilla gorilla). Using a near complete mating record for five females during gestation, we show that pregnant females varied in the timing and frequency of mating, and used PC mating conditionally, synchronizing copulations to occur on days when other females mated, and refraining from mating for lengthy periods when no other females mated. As pregnant females mated exclusively with the same male before and after conception, and mated in response to group female (and not male) behavior, we conclude that western gorillas used PC mating as a form of female competition, and not to confuse paternity or to obtain immediate benefits from the male, as suggested earlier. The male initiated copulations preferentially with females of high rank, rather than distinguishing between pregnant and cycling females. Therefore, PC mating appears to be a strategy by which high-ranking pregnant females attempt to minimize male interest in other females, while reinforcing their own status and potentially delaying conception in others. These findings indicate that female-mating competition is more important than considered earlier, and may be a factor in the evolution of nonconceptive mating in humans. © 2009 Wiley-Liss, Inc.

Citation

Doran-Sheehy, D. M., Fernández, D., & Borries, C. (2009). The strategic use of sex in wild female western gorillas. American Journal of Primatology, 71(12), 1011-1020. https://doi.org/10.1002/ajp.20743

• Journal Article Type: Article
• Acceptance Date: Jul 30, 2009
• Online Publication Date: Aug 31, 2009
• Publication Date: Dec 1, 2009
• Deposit Date: Jun 12, 2017
• Journal: American Journal of Primatology
• Print ISSN: 0275-2565
• Electronic ISSN: 1098-2345
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 71
• Issue: 12
• Pages: 1011-1020
• DOI: https://doi.org/10.1002/ajp.20743
• Keywords: post-conceptive mating, female reproductive competition, mating synchrony
• Public URL: https://uwe-repository.worktribe.com/output/989608
• Publisher URL: http://dx.doi.org/10.1002/ajp.20743
• Additional Information: Additional Information : "This is the peer reviewed version of the following article: Doran-Sheehy, D. M., Fernández, D. and Borries, C. (2009) The strategic use of sex in wild female western gorillas. American Journal of Primatology, 71 (12). pp. 1011-1020. ISSN 02752565 Available from: http://eprints.uwe.ac.uk/32010, which has been published in final form at http://dx.doi.org/10.1002/ajp.20743. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.