Huang Pengzhen, Zhang Endi, Chen Min
School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, Shanghai, China.
Primates. 2018 Sep;59(5):413-421. doi: 10.1007/s10329-018-0666-7. Epub 2018 Jun 5.
It has been suggested that social relationships are more likely to be prone to variation in the dispersing sex than the philopatric sex. However, we know less about the dynamics of all-male groups in male-dispersing species than we do about other types of primate groups. We studied male sociality in a captive group of golden snub-nosed monkeys (Rhinopithecus roxellana), which was composed of a one-male unit (OMU, N = 7) and an all-male unit (AMU, N = 7 or 8), in Shanghai Wild Animal Park, China. Using data collected for 6 months, during which there was a demographic change in the AMU and the alpha male was replaced by a newcomer, we found that a dramatic change in social ranks occurred accompanied by elevated aggression following this social upheaval. A proximity-based social network analysis revealed that members did not associate randomly any more but formed differentiated relationships post-upheaval, resulting in three distinct sub-units in the AMU. In terms of inter-unit interactions, significant changes were found in the affiliations between the male juvenile of OMU and AMU individuals. He interacted with AMU individuals randomly and frequently pre-upheaval, but cut down his affiliations and had a preferred partner post-upheaval, who was a member of the dominant male's sub-unit. Our findings suggest that social networks in the dispersing sex are dynamic structures and vary by some demographic change (e.g., individual immigration) in the studied species. We also put forward that individual dominance could be a criterion when the male juvenile chooses partners before he immigrates into a group. In conclusion, the high level of behavioral flexibility of the dispersing sex could be an evolutional strategy and good for individuals' future dispersing life.
有人提出，与留居性别的个体相比，扩散性别的个体之间的社会关系更易发生变化。然而，相较于其他类型的灵长类群体，我们对雄性扩散物种中全雄群体的动态了解较少。我们在中国上海野生动物园对一群圈养的川金丝猴（Rhinopithecus roxellana）的雄性社交行为进行了研究，该群体由一个单雄单元（OMU，N = 7）和一个全雄单元（AMU，N = 7或8）组成。利用为期6个月收集的数据，在此期间AMU发生了种群结构变化，原首领雄性被一个新来者取代，我们发现，这场社会动荡之后，社会等级发生了巨大变化，同时攻击行为也有所增加。基于接近度的社会网络分析表明，成员之间不再随机交往，而是在动荡后形成了有差异的关系，导致AMU中出现了三个不同的亚单元。在单元间互动方面，OMU的雄性幼崽与AMU个体之间的关联发生了显著变化。在动荡前，它与AMU个体随机且频繁地互动，但在动荡后减少了交往，并拥有了一个偏好的伙伴，该伙伴是占主导地位雄性所在亚单元的成员。我们的研究结果表明，扩散性别的个体的社会网络是动态结构，会因研究物种中的某些种群结构变化（如个体迁入）而有所不同。我们还提出，个体优势可能是雄性幼崽在迁入一个群体之前选择伙伴的一个标准。总之，扩散性别的个体高度的行为灵活性可能是一种进化策略，有利于个体未来的扩散生活。
