Abstract

For many group-living animals, acquiring adult dominance rank is an important social transition. In species with maternal rank “inheritance,” juveniles appear to acquire their adult rank by receiving coalitionary support from kin and by altering patterns of aggressive behavior as they age. Previous studies of rank acquisition, however, have focused on species with high rates of aggression and coalitionary support. We studied rank acquisition in blue monkeys, a species with relatively low aggression and coalition rates, hypothesizing that individualistic changes in agonistic behavior would accompany rank acquisition while the presence of potential coalition partners would be relatively unimportant. Focusing on juvenile females in a wild population, we evaluated latency to reach maternal status and assessed how agonistic behavior changed with age. We also compared rank acquisition in orphaned vs. non-orphaned juveniles. Females from higher ranking matrilines and those in larger groups took longer to reach their maternal status and having more kin did not accelerate rank acquisition. As they aged, subjects were more likely to show aggression to individuals that they were expected to outrank as adults. Female juveniles also appeared to work their way up the hierarchy by overturning ranks with groupmates sequentially. Most orphans reached their matrilineal rank, though orphans were less likely to reach their matrilineal rank than non-orphans, suggesting that in some cases mothers do play an important role in rank acquisition. Orphans with more or high-ranking kin were not more likely to reach their matrilineal rank. These results support the hypothesis that age-related changes in agonistic behavior accompany rank acquisition in blue monkeys while the availability of kin as coalition partners often has little effect on the process. Behavioral mechanisms underlying maternal rank acquisition may vary between closely related species in conjunction with other patterns of social behavior, such as aggression and coalition rates.

Significance statement

In group-living animals with matrilineal hierarchies, individuals are born low-ranking, but eventually acquire a rank similar to their mother’s. In species with high rates of aggression and coalition formation, juveniles reach their mother’s rank by receiving support from kin in aggressive interactions, and by selectively directing aggression to groupmates from lower ranking families. We studied maternal rank acquisition in blue monkeys, hypothesizing that the process might occur differently in a species with low rates of aggression and coalitions. Indeed, the availability of kin appeared to have limited effects on rank acquisition. Maternal rank acquisition was, however, associated with age-related changes in juvenile behavior. We concluded that in some species with matrilineal hierarchies, rank acquisition might occur relatively independent of support from kin.

中文翻译：

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攻击性和联盟率低的灵长类动物的产妇等级获得

摘要

对于许多成群生活的动物来说，获得成年的统治地位是一个重要的社会转变。在具有母体等级“继承力”的物种中，青少年似乎可以通过获得亲属的联合支持并随着年龄的增长改变攻击行为的方式来获得成年等级。但是，先前的等级获取研究集中于具有高侵略性和联盟支持率的物种。我们研究了蓝猴子（一种攻击性和联盟率相对较低的物种）的等级获取，并假设在等级行为获得的同时伴随着激动行为的个人主义变化，而潜在的联盟伙伴的存在则相对不那么重要。针对野生人群中的未成年女性，我们评估了达到母体状态的潜伏期，并评估了激动行为如何随年龄而变化。我们还比较了孤儿与非孤儿的等级获得情况。来自较高母系的女性和较大群体的女性需要更长的时间才能达到产妇地位，而拥有更多的亲戚并不能加速获得等级。随着年龄的增长，受试者更有可能表现出对个人的攻击性，认为他们在成年后的排名会更高。女少年也似乎通过依次推翻同班人的队伍而在等级制度中发挥了作用。大多数孤儿都达到了母系等级，尽管孤儿比非孤儿更不可能达到母系等级，这表明在某些情况下母亲确实在等级获得中起着重要作用。有更多或更高亲戚的孤儿不太可能达到他们的母系等级。这些结果支持以下假设：与年龄相关的激动行为会随蓝猴的等级获得而变化，而亲属作为联盟伙伴的可用性通常对这一过程几乎没有影响。产妇等级获得的基本行为机制在密切相关的物种之间以及与其他社会行为模式（例如，侵略和同盟率）一起可能会有所不同。

重要性声明

在具有母系等级制度的集体生活动物中，个体天生排名较低，但最终获得的排名与母亲相似。在具有高侵略性和联盟形成率的物种中，少年通过在亲密互动中获得亲属的支持，并有选择地将侵略指向低等家庭的同伴，从而达到其母亲的地位。我们研究了蓝猴中的母体等级获取，假设该过程可能在侵略和联盟率较低的物种中以不同的方式发生。确实，亲属的可获得性似乎对等级获得的影响有限。但是，产妇等级的获得与青少年行为中与年龄有关的变化有关。我们得出的结论是，在某些具有母系等级制度的物种中，