Oestrous females avoid mating in front of adult male bystanders in wild chacma baboons.

Alice Baniel,Guy Cowlishaw,Elise Huchard,Axelle Delaunay

doi:10.1098/rsos.181009

Abstract

In social species, female mating strategies can be constrained by both male and female groupmates through sexual conflict and reproductive competition, respectively. This study tests if females adjust their sexual behaviour according to the presence of male and female bystanders in wild chacma baboons (Papio ursinus) and assesses their relative importance. Our results show that oestrous females initiate fewer copulations in the presence of adult male bystanders, irrespective of whether they are mate-guarded or not. This inhibitory effect probably reflects a response to indirect sexual coercion by males, whose close proximity may dissuade females to initiate copulations with rival males to avoid punishment and/or aggressive mating interference. By contrast, females initiate more matings with their mate-guard in the presence of higher-ranking female bystanders, which may reflect an attempt to secure bodyguard services from their mate when they feel threatened. These results emphasize the importance of intra- and intersexual conflicts in shaping female sexual behaviour in this promiscuous society.

Highlights

In social species, male and female groupmates frequently constrain the reproductive strategies of females
This study examines the relative importance of male and female bystanders on female mating behaviour in wild chacma baboons (Papio ursinus)
Our results show that oestrous females modulate their mating activity in the presence of adult male bystanders in wild chacma baboons

Summary

Introduction

Male and female groupmates frequently constrain the reproductive strategies of females. Males may attempt to control female sexuality through the use of forced copulations, sexual harassment, intimidation and punishment [2,3,4]. Females may evolve counter-strategies to alleviate the costs of social control, by inhibiting or 2 hiding copulations in the presence of potentially aggressive bystanders [5,6]. Copulations are conspicuous because females give loud vocalizations at the end of the copulation These copulation calls are thought to be sexually selected traits that advertise female sexual receptivity to stimulate male–male competition and/or sperm competition—and obtain higher quality offspring [7,8,9,10], or to confuse paternity and reduce infanticide risk [11]. Females and subordinate males are more likely to copulate and emit copulation calls when dominant males are out of sight in wild geladas (Theropithecus gelada) [12] and in captive macaques (Macaca mulatta and Macaca fascicularis) [6,13,14], while in chimpanzees (Pan troglodytes), the presence of high-ranking females around a mating couple inhibits the emission of copulation calls [15,16]

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Conclusion