Sexual Interference Behaviors in Male Adult and Subadult Tibetan Macaques (Macaca thibetana).

Kui-Hai Pang,Lori K Sheeran,Dong-Po Xia,Jin-Hua Li,Lixing Sun,Amanda K Rowe

doi:10.3390/ani11030663

Abstract

Simple SummarySexual interference behaviors (interruption/harassment) by male nonhuman primates can lead copulating individuals to separate and is hypothetically a form of male–male competition for access to sexually receptive females. Tibetan macaques (Macaca thibetana) provide an example of male sexual interference that can be used to discuss the sexual competition hypothesis. We found male sexual interference in this species showed significant seasonal variation. Age did not affect the proportion or type of interference behaviors that a male performed, but his social status did. Dominant males more often interrupted copulations. Subordinate males more often directed harassment behaviors toward dominant males, which reduced copulation duration, especially the post-ejaculatory phase of copulation. Our results suggest that sexual interference (interruption or harassment) may be a tactic to reduce the mating success of other males by either preventing ejaculation or reducing the duration of the post-ejaculatory phase, which is critical for sperm transport and, thus, reproductive success. Male nonhuman primate sexual interference, which includes copulation interruption and copulation harassment, has been related to reproductive success, but its significance has been challenging to test. Copulation interruption results in the termination of a copulation before ejaculation, whereas copulation harassment does not. We conducted this study using the all-occurrence behavior sampling method on sexual interference behaviors of seven adult and four subadult male Tibetan macaques (Macaca thibetana) in mating and non-mating seasons at Mt. Huangshan, China, from August 2016 to May 2017. Our results showed that males’ individual proportion of copulation interruption and harassment was higher during the mating season than during the non-mating season. In addition, dominant males more often performed interruption, whereas subordinate males more often performed harassment. We found no difference in the individual proportion of copulation interruption or harassment between adult and subadult males. Adult and subadult males both directed copulation interruption and harassment more often toward the mating male than toward the mating female. Lastly, the post-ejaculation phase of copulation was shorter when copulation harassment occurred than when it did not. Our results suggest that sexual interference may be an important mating tactic that adult and subadult males use in male–male sexual competition.

Highlights

A male’s reproductive success may change throughout the male’s lifetime, and the use of an effective mating strategy may assist the male in male–male mating competition [1].A male may increase their reproduces success either by maximizing males’ own mating opportunity or disrupting competitors’ copulation [2,3]
Sexual interference has been observed in many nonhuman primate species [7,55,56,57], but studies focusing on the quantification of sexual interference behaviors are rare
Our results showed that sexual interference was common in male Tibetan macaques and supported our hypothesis that variation occurs in sexual interference behaviors across adult and subadult male Tibetan macaques

Summary

Introduction

A male’s reproductive success may change throughout the male’s lifetime, and the use of an effective mating strategy may assist the male in male–male mating competition [1].A male may increase their reproduces success either by maximizing males’ own mating opportunity or disrupting competitors’ copulation [2,3]. Interference in the copulatory behaviors of mating pairs is a strategy that may limit the competitor’s mating success in nonhuman primates and other species [3,4,5,6,7,8]. Sexual interference is any form of disruptive behavior in which group member(s) influence or attempt to influence a dyad’s ongoing copulatory behaviors [3,4,5,6,7,8]. Examples of interference behaviors include group members approaching mating males and females and vocalizing, reaching toward, and slapping at the mating male and/or female, moving around the pair, and sometimes making physical contact with them [9,13,14,15]. Sexual interference occurs in two forms: copulation interruption and copulation harassment

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Conclusion