Gregory Tremaine, Bowler Mark
Center for Conservation Education and Sustainability, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, D.C.
San Diego Zoo Global Institute for Conservation Research, Escondido, California.
Am J Primatol. 2016 May;78(5):550-60. doi: 10.1002/ajp.22404. Epub 2015 Apr 6.
Cooperation and affiliation between males may be key to the evolution of large multimale-multifemale primate groups in some species. Cacajao and Chiropotes form multimale-multifemale groups larger than those of most other platyrrhines (Cacajao: over 150 and Chiropotes: up to 80 individuals), and groups exhibit a high degree of fission-fusion dynamics. In both genera, males engage in affiliative, sex-specific behaviors and form all-male parties. Males in both genera also have conspicuous genitalia but can demonstrate sexual crypsis, or mimicry, wherein testes are retracted, resembling labia. Observed egalitarian interactions among males suggest that there is scramble competition for access to females, and aggression between males is uncommon relative to other social primates. As of yet, there are no genetic data to clarify dispersal patterns, and while relatedness among males would in part explain their affiliative relationships, there is some limited evidence for dispersal by males in Cacajao. In this review of recent studies of male-male social interactions in Chiropotes and Cacajao, we posit that the ability to maintain large groups in these genera may be related to the affiliative and perhaps coalitionary relationships between males, who may or may not be related. Affiliative male-male relationships may allow for monopolization of groups of females and facilitate group cohesion by reducing intragroup aggression; however data on male-male interactions with identified individuals will be required to determine patterns of affiliation, while genetic studies may be the most practical way of determining dispersal patterns for these genera.
在某些物种中，雄性之间的合作与联合可能是大型多雄多雌灵长类群体进化的关键。僧面猴属和绒毛蛛猴属形成的多雄多雌群体比大多数其他阔鼻猴类的群体更大（僧面猴属：超过150只，绒毛蛛猴属：多达80只个体），并且群体表现出高度的裂变-融合动态。在这两个属中，雄性会表现出具有性别特异性的亲和行为，并形成全雄群体。这两个属的雄性也都有明显的生殖器，但能表现出性隐避或拟态，即睾丸缩回，类似阴唇。观察到的雄性之间平等的互动表明，在获取雌性方面存在争夺竞争，并且相对于其他社会性灵长类动物，雄性之间的攻击行为并不常见。截至目前，尚无遗传数据来阐明扩散模式，虽然雄性之间的亲缘关系在一定程度上可以解释它们的亲和关系，但在僧面猴属中，有一些有限的证据表明雄性会扩散。在这篇对绒毛蛛猴属和僧面猴属中雄性间社会互动的近期研究的综述中，我们认为，这两个属维持大群体的能力可能与雄性之间的亲和关系以及或许的联盟关系有关，这些雄性可能有亲缘关系，也可能没有。雄性之间的亲和关系可能允许对雌性群体的垄断，并通过减少群体内的攻击行为来促进群体凝聚力；然而，需要关于与已识别个体的雄性间互动的数据来确定亲和模式，而遗传研究可能是确定这些属的扩散模式的最实用方法。
