Doctoral Dissertation Improvement: The Reproductive Trajectories of Geladas (Theropithecus gelada)

牢固的雄性关系在灵长类动物中很少见，尤其是雌性结合的物种。因此，在雌性结合的物种中，雄性结合与生殖策略之间的关系在很大程度上仍未得到研究。狒狒（Theropithecus gelada）为理解雄性结合如何影响雌性结合物种的雄性生殖轨迹提供了一个理想的模型。在获得与雌性交配的机会之前，“单身”狒狒生活在有凝聚力的全雄性群体中。最终，雄性从这些群体中毕业，获得与一群雌性（一雄单位）的唯一生殖机会。单身汉们通过以下几种策略之一获得一个雄性单位：(1)直接推翻领头的雄性；(2)顺从地进入一个单位，并试图随着时间的推移将雌性从单位中分离出来；(3)利用最近接管的混乱局面，机会主义地与雌性交配。此外，人们还观察到，单身汉们会合作，试图推翻领头的雄性，并与原来的全雄性群体成员一起进入单雄性群体——但最终只有一只雄性获得了繁殖的好处。该项目研究了狒狒从全雄性群体向单雄性群体转变过程中，影响雄性狒狒繁殖轨迹的行为和激素因素。研究人员将(i)描述单身汉在全男性群体中的社会互动；（ii）确定影响单身汉参与领导雄性接管尝试的行为和激素因素，（iii）确定单身汉质量是否预测生殖策略。行为数据和非侵入性粪便激素取样将记录雄性狒狒的生殖轨迹。此外，将拍摄男性胸部斑块颜色的数码照片——一种可能表明男性品质的特征——以记录男性从单身群体转向单男性群体时颜色的变化。这项研究的结果将为这些稀有灵长类动物的保护决策提供信息，而调查员在四面山国家公园的存在有助于阻止这一濒危世界遗产的非法活动。该项目为埃塞俄比亚当地的实地助理提供收入和培训，合作项目还安排向美国几个州的高中生解释狒狒的行为。

Strong male bonds are rare among primates, especially for female-bonded species. Thus, the relationship between male bonding and reproductive strategies remains largely unexamined in female-bonded species. Geladas (Theropithecus gelada) provide an ideal model for understanding how male bonds influence male reproductive trajectories in a female-bonded species. Prior to acquiring reproductive access to females, "bachelor" geladas live in cohesive all-male groups. Eventually, males graduate from these groups to gain sole reproductive access to a group of females (one-male unit). Bachelors acquire one-male units using one of several strategies: (1) directly overthrowing the leader male, (2) submissively entering a unit and attempting to pare females away from the unit over time, or (3) capitalizing on the chaos of a recent takeover to opportunistically mate with females. Additionally, bachelors have been observed to cooperate in attempts to overthrow leader males and enter one-male units with former members of their all-male group - yet only one male eventually reaps the reproductive benefits. This project investigates the behavioral and hormonal factors that shape the reproductive trajectory of gelada males as they move from an all-male group to a one-male unit. The researchers will(i) describe the social interactions among bachelors within their all-male group; (ii) determine the behavioral and hormonal factors that influence bachelor participation in takeover attempts of leader males, and (iii) determine whether bachelor quality predicts a reproductive strategy. Behavioral data and noninvasive fecal hormone sampling will document the reproductive trajectories of male geladas. Additionally, digital photographs will be taken of male chest patch color - a feature that may indicate male quality - to document changes in color as males move from their bachelor groups to one-male units. Results from this research will inform conservation decisions regarding these rare primates, and the investigator's presence in the Simien Mountains National Park help deter illegal activities in this World Heritage Site that is in danger. This project provides income and training to local Ethiopian field assistants and the co-PI has arranged to explain gelada behavior to high school students in several U.S. states.