Data from: Patterns of interventions and the effect of coalitions and sociality on male fitness

In group living animals, especially among primates, there is consistent evidence that high-ranking males gain a higher reproductive output than low-ranking males. Primate studies have shown that male coalitions and sociality can impact male fitness; however, it remains unclear whether males could potentially increase their fitness by preferentially supporting and socializing with females. Here we investigate patterns of male interventions and the effect of coalitions and sociality on male fitness in rhesus macaques (Macaca mulatta) with particular focus on male-female interactions. We combined behavioral collected on Cayo Santiago with genetic data analyzed for male reproductive output and relatedness. Our results revealed that the ten top-ranking males provided the majority of all male support observed. In contrast to other primates, male rhesus macaques mainly formed all-down coalitions suggesting that coalitions are less likely used to enhance male dominance. Males supporting females during and before their likely conception were not more likely to fertilize those females. We also found no evidence that males preferably support their offspring or other close kin. Interestingly, the most important predictor of male support was sociality, since opponents sharing a higher sociality index with a given male were more likely to be supported. Furthermore, a high sociality index of a given male-female dyad resulted in a higher probability of paternity. Overall, our results strengthen the evidence that sociality affects fitness in male primates, but also suggest that in species in which males queue for dominance, it is less likely that males derive fitness benefits from coalitions.

在群居动物中，尤其是灵长类动物，已有一致的研究证据表明，地位较高的雄性个体的繁殖产出显著高于地位较低的雄性。灵长类动物相关研究已证实，雄性联盟与社交性会对雄性进化适合度产生影响，但目前仍不清楚雄性是否可通过优先支持雌性并与之建立社交互动来提升自身适合度。本研究以恒河猴（Macaca mulatta）为研究对象，探究雄性干预行为模式、联盟与社交性对雄性适合度的影响，并重点关注雌雄个体间的互动。我们整合了在圣地亚哥岛（Cayo Santiago）采集的行为学数据，以及用于分析雄性繁殖产出与亲缘关系的遗传学数据。研究结果显示，在所有观测到的雄性支持行为中，排名前十的雄性个体贡献了绝大多数。与其他灵长类动物不同，恒河猴雄性主要组建全下级联盟，这提示联盟不太可能被用于强化雄性的统治地位。在雌性可能受孕的时段及此前为其提供支持的雄性，并未更大概率地使该雌性受孕。我们还未发现雄性优先支持自身后代或其他近缘亲属的相关证据。值得注意的是，雄性支持行为的最强预测因子为社交性：与特定雄性社交指数越高的个体，越有可能获得该雄性的支持。此外，特定雌雄配对的高社交指数，会显著提升该配对的父权获得概率。总体而言，本研究结果进一步证实了社交性会影响雄性灵长类的进化适合度，同时也表明，在雄性通过顺位获取统治地位的物种中，雄性不太可能从联盟行为中获得适合度方面的收益。