Doctoral Dissertation Improvement: The ontogeny of male-male bonds in wild Ethiopian geladas (Theropithecus gelada)

尽管雄性亲缘关系在雄性亲缘关系的灵长类动物中相对常见，但在雄性分散的物种中，这种关系的证据却很少。尽管有文献表明，在这种情况下，雄性之间的纽带会对生殖产生影响，但人们对这些纽带是如何形成的知之甚少。在Daniel Rubenstein博士的指导下，普林斯顿大学的博士生Caitlin Barale研究了狒狒（Theropithecus gelada）中雄性-雄性关系的个体发生。狒狒是一种以雄性分散和雄性-雄性结合为特征的物种。本研究的主要目的是研究雄性狒狒幼崽从出生时的单雄性个体，到临时同伴群体，再到全雄性单身群体，在个体生殖轨迹上形成的行为和激素因素。该项目有四个具体目标：(1)描述青少年同伴群体；(2)描述青少年时期男性与男性之间的联系；(3)评估这些联系的短期效益；(4)调查男性关系在肾上腺期如何变化。研究人员对埃塞俄比亚塞米恩山脉国家公园的所有幼年雄性狒狒（N=51）进行了横断面和纵向行为分析、社会网络分析和非侵入性粪便激素取样。这项研究是第一个专门针对幼年狒狒的长期研究。通过收集行为、生理和网络数据，为研究狒狒的社会发展提供了一个有价值的新视角，并建立了第一个关于已知雄性狒狒的纵向数据集。有了已知个体从幼年到成年的详细数据，研究人员可以将早期生活的影响与一生的生殖成功联系起来。本研究结果将为研究灵长类动物雄性-雄性关系的发展提供新的数据，推动社会网络理论在动物系统中的应用，并有助于建立早期古人类、现代人类和其他非人类灵长类动物的社会发展模型。

Although male-male bonds are relatively common in male-philopatric primates, evidence for these bonds in species with male dispersal is rare. Despite documentation that male-male bonds have reproductive consequences in this context, little is known about how these bonds develop. Doctoral student Caitlin Barale (Princeton University), under the supervision of Dr. Daniel Rubenstein, investigates the ontogeny of male-male relationships in the gelada (Theropithecus gelada), a species characterized by both male dispersal and male-male bonds. The primary objective of this research is to examine the nature of male-male bonds, and identify the behavioral and hormonal factors that set juvenile gelada males on individual reproductive trajectories as they transition from their natal one-male unit, to a temporary peer group, and onwards into an all-male bachelor group. The project has four specific goals: (1) to describe juvenile peer groups, (2) to characterize male-male bonds in the juvenile period, (3) to evaluate a short-term benefit of these bonds, and (4) to investigate how male relationships change at adrenarche. The investigators employ a combination of cross-sectional and longitudinal behavioral analyses, social network analysis and non-invasive fecal hormone sampling on all juvenile males (N=51) in a band of geladas in the Simien Mountains National Park, Ethiopia.This research represents the first long-term study focused exclusively on juvenile geladas. It provides a valuable new perspective on gelada social development through the collection of behavioral, physiological and network-based data, and initiates the first longitudinal dataset on known gelada males. Having detailed data on known individuals from juvenility to adulthood allows researchers to connect the effects of early life to lifetime reproductive success. The results of this research will contribute novel data on the development of male-male bonds in primates, advance the application of social network theory to animal systems, and help build a model for social development in early hominins, modern-day humans, and other non-human primates.