Data from: The socio-genetics of a complex society: female gelada relatedness patterns mirror association patterns in a multi-level society.

Multilevel societies with fission–fusion dynamics—arguably the most complex animal societies—are defined by two or more nested levels of organization. The core of these societies are modular social units that regularly fission and fuse with one another. Despite convergent evolution in disparate taxa, we know strikingly little about how such societies form and how fitness benefits operate. Understanding the kinship structure of complex societies could inform us about the origins of the social structure as well as about the potential for individuals in these societies to accrue indirect fitness benefits. Here, we combined genetic and behavioural data on geladas (Theropithecus gelada), an Old World Monkey, to complete the most comprehensive socio-genetic analysis of a multilevel society to date. In geladas, individuals in the core social ‘units’, associate at different frequencies to form ‘teams’, ‘bands’ and, the largest aggregations, ‘communities’. Units were composed of closely related females, and females remained with their close kin during permanent fissions of units. Interestingly, female–female relatedness also significantly predicted between-unit, between-team and between-band association patterns, while male–male relatedness did not. Thus, it is likely that the socio-genetic structure of gelada society results from females maintaining associations with their female relatives during successive unit fissions—possibly in an attempt to balance the direct and indirect fitness benefits of group living. Overall, the persistence of associations among related females across generations appears to drive the formation of higher levels of gelada society, suggesting that females seek kin for inclusive fitness benefits at multiple levels of gelada society具有裂变-融合动态（fission–fusion dynamics）的多级社会（multilevel societies）——可说是最为复杂的动物社会——由两层及以上的嵌套组织层级所定义。这类社会的核心为模块化社会单元（modular social units），这些单元会定期发生裂变并彼此融合。尽管在不同类群中均出现了这类社会的趋同演化，但我们对这类社会的形成机制以及适合度收益（fitness benefits）的运作模式仍知之甚少。解析复杂社会的亲缘结构（kinship structure），有助于我们理解社会结构的起源，同时也能揭示这类社会中个体获取间接适合度收益（indirect fitness benefits）的潜在可能。本研究结合了旧世界猴（Old World Monkey）狮尾狒（Theropithecus gelada）的遗传学与行为学数据，完成了迄今为止针对多级社会最为全面的社会遗传学（socio-genetic）分析。在狮尾狒社会中，核心社会"单元"内的个体会以不同的关联频率组建"团队"、"群队"，以及规模最大的聚合体"社群"。单元由亲缘关系紧密的雌性个体组成，且在单元发生永久性裂变时，雌性个体仍会与近亲结伴。值得注意的是，雌性间的亲缘关系同样显著预测了单元间、团队间以及群队间的关联模式，而雄性间的亲缘关系则无此关联。由此可见，狮尾狒社会的社会遗传学结构，大概率源于雌性个体在连续的单元裂变过程中，始终与雌性亲属保持结伴——这或许是为了平衡群体生活的直接与间接适合度收益。总体而言，亲缘雌性个体间的关联在多代间得以维持，这似乎推动了狮尾狒社会更高层级结构的形成，这表明雌性个体会在狮尾狒社会的多个层级中寻求亲缘伙伴，以获取广义适合度收益（inclusive fitness benefits）。