From groups to communities in western lowland gorillas

Social networks are the result of interactions between individuals at different temporal scales. Thus, sporadic intergroup encounters and individual forays play a central role in defining the dynamics of populations in social species. We assessed the rate of intergroup encounters for three western lowland gorilla (Gorilla gorilla gorilla) groups with daily observations over five years, and noninvasively genotyped a larger population over four months. Both approaches revealed a social system much more dynamic than anticipated, with non-aggressive intergroup encounters that involved social play by immature individuals, exchanges of members between groups likely modulated by kinship, and absence of infanticide evidenced by infants non fathered by the silverback of the group where they were found. This resulted in a community composed of groups that interacted frequently and non-aggressively, contrasting with the more fragmented and aggressive mountain gorilla (G. beringei beringei) societi...

社交网络是个体在不同时间尺度上互动的结果。因此，偶发的群间相遇与个体的外出活动在塑造社会性物种的种群动态中发挥核心作用。我们通过五年的每日观察，评估了三个西部低地大猩猩（Gorilla gorilla gorilla）群体的群间相遇率，并在四个月内对更大规模的种群进行了无创基因分型。两种方法均揭示出一个远比预期更具动态性的社会系统：群间相遇无攻击性，涉及未成年个体的社交玩耍；群体间成员交换可能受亲缘关系调节；且未发现杀婴行为——证据是部分婴儿的父亲并非其所在群体的银背大猩猩。这形成了一个由频繁且无攻击性互动的群体构成的社群，与更为分散且具攻击性的山地大猩猩（G. beringei beringei）社会形成鲜明对比……