Complex sources of variance in female dominance rank in a nepotistic society

Many mammalian societies are structured by dominance hierarchies, and an individual's position within this hierarchy can influence reproduction, behaviour, physiology and health. In nepotistic hierarchies, which are common in cercopithecine primates and also seen in spotted hyaenas, Crocuta crocuta, adult daughters are expected to rank immediately below their mother, and in reverse age order (a phenomenon known as ‘youngest ascendancy’). This pattern is well described, but few studies have systematically examined the frequency or causes of departures from the expected pattern. Using a longitudinal data set from a natural population of yellow baboons, Papio cynocephalus, we measured the influence of maternal kin, paternal kin and group size on female rank positions at two life history milestones, menarche and first live birth. At menarche, most females (73%) ranked adjacent to their family members (i.e. the female held an ordinal rank in consecutive order with other members of her matern...

许多哺乳动物社群以支配等级为结构框架，个体在该等级中的地位可对其繁殖、行为、生理状态与健康状况产生显著影响。在裙带主导的等级体系中——这类体系常见于猕猴亚科灵长类，也见于斑鬣狗（Crocuta crocuta）——成年雌性后代的顺位理应紧邻其母亲，且遵循年龄逆序排列（该现象被称为「年幼优先上位」）。该等级模式已有充分研究描述，但鲜有工作系统性地探究偏离该预期模式的发生频率与成因。本研究依托黄狒狒（Papio cynocephalus）自然种群的纵向数据集，分析了母系亲属、父系亲属以及群体规模对雌性在两个生命史关键节点——初潮与首次产仔——时的顺位的影响。在初潮阶段，多数雌性（73%）的顺位与其家族成员相邻（即该雌性的序数顺位与其母系亲属的其他成员呈连续顺序……