Data from: Group size differences may mask underlying similarities in social structure: a comparison of female elephant societies

Fission-fusion dynamics allow for the costs and benefits of sociality to be regulated through changes in group size. There are different modal fission-fusion societies, and female Asian and African elephant populations examined so far have shown different social structures and average group sizes. We report on female Asian elephant social structure in Nagarahole and Bandipur National Parks (Kabini population), southern India, and examine the role of group size in affecting the outcome of social structure analysis in female elephants. Based on five years of data, we found the Kabini association network structured into highly modular communities that we call clans. A comparison of the Kabini dataset, modified to match sampling methods, with previously published Uda Walawe Asian elephant and Samburu African elephant data showed that measures of association and network structure were more similar amongst the Asian elephant populations compared to Samburu. The Samburu population formed a hierarchically-nested multilevel society whereas the Asian populations did not. However, we found hierarchical levels in all three populations using Louvain community detection. Moreover, the average community sizes obtained through the Louvain method were not significantly different across populations, indicating basic similarities in social structure. We examined the effect of average group size on association and network statistics. Higher average association index and degree, and lower average path length in Samburu compared to Kabini were explained by larger average group size in Samburu. Thus, underlying similarities in the social networks of species showing fission-fusion dynamics may be obscured by differences in average group size.裂合动态（fission-fusion dynamics）可通过调整群体规模，调控社会性活动的成本与收益。裂合社会存在多种典型模态，目前已被研究的亚洲象与非洲象雌性种群，均展现出差异化的社会结构与平均群体规模。本研究针对印度南部纳加尔霍莱与班迪普尔国家公园内的亚洲象雌性种群（卡比尼种群）的社会结构展开报道，并探究群体规模对雌性象社会结构分析结果的影响作用。基于五年的调研数据，本研究发现卡比尼种群的关联网络可划分为多个高度模块化的社群，我们将其称之为宗族（clans）。我们将经过采样方法适配性调整的卡比尼数据集，与已公开的乌达瓦拉维亚洲象种群及桑布鲁非洲象种群数据进行对比后发现：相较于桑布鲁种群，亚洲象种群间的关联度指标与网络结构特征更为相似。桑布鲁非洲象种群形成了具有层级嵌套特征的多层级社会，而亚洲象种群则未呈现该结构。不过，通过卢万社群检测算法（Louvain community detection）分析，我们发现三个种群均存在层级结构。此外，通过该算法得到的平均社群规模在不同种群间并无显著差异，这表明三者的社会结构存在基本共性。我们还探究了平均群体规模对关联度指标与网络统计特征的影响。相较于卡比尼种群，桑布鲁种群拥有更高的平均关联指数与节点度，同时平均路径长度更低，这一差异可由桑布鲁种群更大的平均群体规模得到解释。由此可见，具有裂合动态的物种其社交网络所潜藏的共性，可能会因平均群体规模的差异而被掩盖。