Instituto de Neuroetología, Universidad Veracruzana, Xalapa, 91190, México; Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, L3 3AF, Liverpool, UK.
Am J Phys Anthropol. 2013 Sep;152(1):86-95. doi: 10.1002/ajpa.22331. Epub 2013 Aug 1.
Dispersal patterns are critical for understanding social systems as they influence social interactions and relationships. Spider monkeys (Ateles spp.) are typically described as being characterized by male philopatry and female dispersal, with these patterns reflected in stronger affiliative and cooperative relationships among males than among females. Recent findings, however, indicate that male-male relationships may not be as uniformly strong as previously thought, which suggests that male philopatry in spider monkeys may not be universal. Here, we report the first confirmed cases of male immigration and group takeover in spider monkeys. Data were collected on one community of Ateles geoffroyi in northwestern Costa Rica. Behavioral and demographic data were recorded during subgroup follows across 6.5 years, and fecal samples of community members were collected for genetic analysis of relatedness. We documented two separate cases of immigration involving multiple males, which resulted in take-over of the study community by extra-community males and the concomitant disappearance of the resident males. In the study community, males were no more closely related to one another, on average, than females were, contrary to what would be expected if males were the more philopatric sex. Comparison of corrected assignment indices for males and females also revealed no evidence of sex-biased dispersal. Our findings suggest that in spider monkeys male immigration may occur under certain demographic circumstances, contributing to a view of greater flexibility in their social system than previously appreciated. This discovery has implications for other species that are typically characterized by male philopatry.
扩散模式对于理解社会系统至关重要，因为它们会影响社会互动和关系。蜘蛛猴（Ateles spp.）通常被描述为雄性亲缘关系和雌性扩散的特征，这些模式反映在雄性之间比雌性之间更强烈的亲和关系和合作关系。然而，最近的发现表明，雄性之间的关系可能并不像以前想象的那样统一强大，这表明蜘蛛猴的雄性亲缘关系可能不是普遍存在的。在这里，我们报告了蜘蛛猴中首次确认的雄性移民和群体接管案例。数据是在哥斯达黎加西北部的一个阿特莱斯·乔治奥伊社区收集的。在 6.5 年的时间里，通过对亚群的跟踪记录了行为和人口数据，并收集了社区成员的粪便样本，用于进行亲缘关系的遗传分析。我们记录了两起涉及多个雄性的移民案例，这些雄性导致了外社区雄性接管了研究社区，而居住的雄性则消失了。在研究社区中，雄性之间的亲缘关系平均而言并不比雌性之间更密切，这与雄性更亲代的性别预期相反。对雄性和雌性校正分配指数的比较也没有发现性别偏向扩散的证据。我们的研究结果表明，在蜘蛛猴中，雄性移民可能会在某些人口环境下发生，这使得我们对它们的社会系统有了更大的灵活性的看法，而不是以前所认为的那样。这一发现对其他通常以雄性亲缘关系为特征的物种具有重要意义。
