Pinheiro Tatyana, Lopes Maria A
Instituto de Desenvolvimento Sustentável Mamirauá, Tefé, Amazonas, Brazil.
Universidade Federal do Pará, Belém, Pará, Brazil.
Primates. 2018 Sep;59(5):475-482. doi: 10.1007/s10329-018-0668-5. Epub 2018 Jun 14.
The dominance structure of primate social groups varies widely. In addition to the groups' composition, intrinsic attributes such as sex, body size and life experience are important factors that can affect hierarchical dominance relations. All primates are social animals, and the social environment has a direct influence on the physiological conditions of vital systems such as immunological, reproductive and cardiovascular systems. In this study, we analyze the hierarchical structure of Saimiri collinsi in captivity, including the hierarchical structure type, the influence of individual intrinsic characteristics (sex, age, weight and origin-born in captivity or in the wild) based on the prior-attributes model, the relation between agonistic behavior frequency and hierarchical position, and hierarchy steepness, which represents the dominance gradient. We found that the group order was characterized by a partial hierarchy: a dominance position could be occupied by more than one individual simultaneously, including individuals of both sexes. Intrinsic characteristics had no influence on hierarchical structure, with the exception of the male in the highest hierarchical position, which had a markedly larger body than all other group members. Thus, the prior-attributes model did not apply to hierarchical formation of S. collinsi in captivity. Only the frequency of agonistic behavior of males correlated with their hierarchical position, and they differed from all other group members in their more aggressive behavior. The steepness between adjacent positions along the dominance gradient was significant only between the dominant male and the next individual in the group, with a smooth gradient between the other positions in the rank. As the access to resources is directly related to hierarchical dominance, a smooth dominance gradient is to be expected in species that form very large groups, such as wild Saimiri populations.
灵长类动物社会群体的优势结构差异很大。除了群体组成外，性别、体型和生活经历等内在属性也是影响等级优势关系的重要因素。所有灵长类动物都是社会性动物，社会环境对免疫、生殖和心血管系统等重要系统的生理状况有直接影响。在本研究中，我们分析了圈养条件下柯氏松鼠猴的等级结构，包括等级结构类型、基于先赋属性模型的个体内在特征（性别、年龄、体重和来源——圈养出生或野外出生）的影响、攻击行为频率与等级地位之间的关系以及代表优势梯度的等级陡峭程度。我们发现，群体秩序的特点是部分等级制度：一个优势地位可以同时被多个个体占据，包括不同性别的个体。内在特征对等级结构没有影响，但处于最高等级地位的雄性除外，其体型明显大于群体中的所有其他成员。因此，先赋属性模型不适用于圈养条件下柯氏松鼠猴的等级形成。只有雄性的攻击行为频率与其等级地位相关，并且它们在行为上比所有其他群体成员更具攻击性。沿着优势梯度相邻位置之间的陡峭程度仅在占主导地位的雄性与群体中的下一个个体之间显著，等级中的其他位置之间的梯度较为平缓。由于资源获取与等级优势直接相关，在形成非常大群体的物种中，如野生松鼠猴种群，预计会有平缓的优势梯度。
