Group size and reproductive success of female and male blue monkeys

社会性是灵长类的一个特征，而理解群体生活的选择优势已被证明是一个持久的问题。研究人员正在肯尼亚卡卡梅加雨林研究六组野生蓝猴（Cercopithecus mitas stuhlmanni），它们的大小相差五倍，以了解群体生活的进化基础。本项目主要研究群体大小的变化对野生雌、雄蓝猴生物适应性的影响。群体规模应反映群体生活对个体群体成员的成本和收益。雌性会为了获得食物而与同伴激烈竞争，当群体变大时，雌性会进行分裂。这样的观察结果表明，在大群体中生活是有代价的，而集体的领土和捕食者的防御（主要是由雌性进行的）也表明了好处。研究小组调查了群体大小是如何影响女性健康的，直接衡量标准是生育间隔、婴儿存活率和第一胎年龄，间接衡量标准是喂养和社会行为。这个物种的雄性试图垄断雌性群体，在更大的群体中应该有更多的繁殖机会。然而，雄性生殖划分模型表明了其他重要因素，如雌性生殖同步性、入侵者压力和雄性自身的生殖历史。这个项目阐明了哪些因素最能解释男性在繁殖方面的巨大差异。研究人员监测人口变化、女性社会和性行为，并收集粪便样本，利用微卫星位点进行遗传父权鉴定。研究人群是少数有长期人口统计数据的人群之一。该项目直接衡量与社会和生态驱动因素相关的生殖结果。本项目支持一名女研究生的学位论文研究，以及其他本科生、硕士生、博士生的研究训练。与肯尼亚一所新大学的国际合作已导致建立与实地地点有关的森林生态学专业知识；项目人员支持一个以社区为基础的基层保护组织，并向正在为卡卡梅加森林制定参与性管理计划的科学小组提供咨询。

Sociality is a hallmark of the primate order, and understanding the selective advantage of group living has proved an enduring question. The researchers are studying six groups of wild blue monkeys (Cercopithecus mitas stuhlmanni), differing five-fold in size, in the Kakamega, Kenya rain forest to understand the evolutionary basis of group living. This project focuses on how variation in group size influences biological fitness in of wild female and male blue monkeys. Group size is expected to reflect costs and benefits of group living to individual group members. Females compete aggressively with group-mates over access to food, and engineer group splits when groups become large. Such observations suggest costs to living in larger groups, while collective territorial and predator defense, mainly by females, also suggests benefits. The research team investigates how group size influences female fitness, measured directly in terms of inter-birth interval, infant survival, and age at first birth, and indirectly by aspects of feeding and social behavior. Males of this species try to monopolize groups of females, and should have more reproductive opportunities in larger groups. Models of male reproductive partitioning suggest additional important factors, however, like female reproductive synchrony, intruder pressure and a male's own reproductive history. This project clarifies which factors best explain the considerable variation in reproduction among males. The researchers monitor demographic changes, female social and sexual behavior, and collect fecal samples for genetic paternity assignment using microsatellite loci. The study population is one of very few in which long-term demographic data exist. This project directly measures reproductive outcomes as related to social and ecological drivers.This project supports the dissertation research of a female graduate student, and research training of other undergraduate, M.A., and Ph.D. students. International collaboration with a new Kenyan university has led to building expertise in forest ecology related to the field site; the project personnel support a grass-roots community-based conservation organization, and advise the scientific team that is developing the participatory management plan for the Kakamega Forest.