Yamaguchi T, Kazahari N
Laboratory of Human Evolution Studies, Graduate School of Science, Kyoto University, Kyoto, Japan.
Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Japan.
Primates. 2022 Nov;63(6):575-582. doi: 10.1007/s10329-022-01011-2. Epub 2022 Sep 2.
The spatiotemporal cohesion of a group is an essential element of primate society. It is thus important to clarify the factors that influence the extent of variation in spatial cohesion and individual membership in a group over time, known as fission-fusion dynamics. During the mating season of 2019, the alpha male (TY) in a wild group of Japanese macaques on Kinkazan Island repeatedly disappeared from the group, and we observed fission-fusion dynamics caused by his movement. The group seemed to have split when TY left the group or its home range, and females who followed him had the most affiliative relationships with TY or were the relatives of those females. Although TY disappeared from the group in the post-mating season, these fission-fusion dynamics only occurred during the mating season probably because females had a more substantial need for protection against aggression from the other males during the mating season. These results indicate that, although rare, fission-fusion dynamics based on affiliative relationships between males and females can occur with the separation of alpha males from the group. More studies in other populations are needed to clarify the influence of group males on the spatial cohesion of groups.
群体的时空凝聚力是灵长类动物社会的一个基本要素。因此，明确影响群体空间凝聚力和个体成员随时间变化程度的因素很重要，这种变化被称为裂变-融合动态。在2019年的交配季节，位于金火山岛的一群野生日本猕猴中的优势雄性（TY）多次从群体中消失，我们观察到了由它的移动引起的裂变-融合动态。当TY离开群体或其活动范围时，群体似乎分裂了，跟随它的雌性与TY有最亲密的关系，或者是那些雌性的亲属。尽管TY在交配季节后从群体中消失了，但这些裂变-融合动态只发生在交配季节，可能是因为雌性在交配季节更需要保护自己免受其他雄性的攻击。这些结果表明，尽管罕见，但基于雄性和雌性之间亲密关系的裂变-融合动态会随着优势雄性与群体的分离而发生。需要对其他种群进行更多研究，以阐明群体中的雄性对群体空间凝聚力的影响。
