Competitive ability determines coalition participation and partner selection during maturation in wild male chimpanzees (Pan troglodytes schweinfurthii)
Competitive ability determines coalition participation and partner selection during maturation in wild male chimpanzees (Pan troglodytes schweinfurthii)
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DOI：
10.1007/s00265-020-02872-7
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发表时间：
2020-06-22
影响因子：
2.3
通讯作者：
Muller, Martin N.
中科院分区：
文献类型：
--
作者：
Enigk, Drew K.;Thompson, Melissa Emery;Muller, Martin N.
社会性哺乳动物通常生活在群体中，其中的统治等级是获得配偶的重要决定因素。除了单独竞争外，雄性还可能组成两个或多个联盟来攻击或恐吓竞争对手。联盟的形成对于青春期男性尤其有利，可以帮助他们弥补身体和社交上的不成熟。然而，由于这些不足，青少年可能很难吸引有效的联盟伙伴。在这里，我们研究了成熟雄性黑猩猩的行为，以测试在强大或较弱的个体中联盟是否更频繁。我们的纵向研究跟踪了 18 名雄性（年龄 5 至 25 岁），并在对乌干达基巴莱国家公园 Kanyawara 黑猩猩群落的 12 年观察中利用了 1517 个联盟。我们发现，随着成熟期，联盟形成率有所增加，而且这种增加与攻击行为总体使用率的增加无关。青少年几乎完全与母亲结成联盟，而青少年则主要与同龄人和成年男性结成伙伴。当青少年和成年男性彼此结成联盟时，青少年更有可能加入成年人，反之亦然。最后，青少年与成年男性的联合行为更常见于非攻击性的声音表现，而不是攻击性的联盟。总而言之，我们的研究结果表明，青春期男性在很大程度上无法吸引最强大的联盟伙伴，并且当受到对手攻击的风险较低时，他们会通过加入成年男性的竞争较少的环境来“充分利用糟糕的工作”。意义陈述 青春期男性在争夺强大盟友时处于不利地位，因为他们为合作二人做出贡献的力量较小。即使存在多种可能的联盟伙伴，地位较高的雄性的伙伴选择也可能会限制剩余的可以并愿意与青少年结成联盟的个体的数量。因此，我们发现，男性会与排名靠前的联盟伙伴进行排序，从而使青少年与与自己级别相似的伙伴组成联盟，而不是与排名较高的成年男性结盟。然而，没有证据表明联合声音展示中存在等级排序。此外，青少年参加的联合声音表演次数是联盟的两倍多。这些数据表明，对于试图融入成年男性社交世界的青少年来说，联合发声展示是联盟的可行替代方案。
Social mammals often live in groups in which a dominance hierarchy is an important determinant of access to mates. In addition to competing individually, males may form coalitions of two or more to attack or intimidate rivals. Coalition formation could be particularly advantageous for adolescent males by helping them compensate for their physical and social immaturity. However, adolescents may struggle to attract effective coalition partners because of these inadequacies. Here, we examine the behavior of maturing male chimpanzees to test whether coalitions are more frequent among more or less powerful individuals. Our longitudinal study followed 18 males (ages 5 through 25 years) and utilized 1517 coalitions across 12 years of observation of the Kanyawara chimpanzee community in Kibale National Park, Uganda. We found that rates of coalition formation increased across maturation and that this increase was independent of a rise in the overall use of aggression. Juveniles formed coalitions almost exclusively with their mothers, while adolescents partnered primarily with peers and adult males. When adolescents and adult males formed coalitions with each other, the adolescents were more likely to join the adults than vice versa. Finally, adolescents engaged in joint behavior with adult males more often in non-aggressive vocal displays than in aggressive coalitions. Taken together, our results suggest that adolescent males are largely unable to attract the most powerful coalition partners and that they "make the best of a bad job" by joining adult males in less competitive situations, when the risk of receiving aggression from opponents is lower. Significance statement Adolescent males are at a disadvantage in competing for powerful allies, because they have less strength to contribute to a cooperative dyad. Even when a variety of possible coalition partners are present, the partner choices of higher-ranking males likely limit the number of remaining individuals that are available and willing to form coalitions with adolescents. Accordingly, we found that males sorted with closely ranked coalition partners down the hierarchy, leaving adolescents to form coalitions with partners of similar rank to themselves rather than high-ranking adult males. There was no evidence for rank sorting in joint vocal displays, however. Additionally, adolescents participated in more than twice as many joint vocal displays as coalitions. These data suggest that joint vocal displays represent a viable alternative to coalitions for adolescents attempting to integrate themselves into the adult male social world.