Niche Expansion and Terrestriality in an Arboreal Primate

大多数灵长类动物行为生态学的比较模型假设野生灵长类动物的行为是适应性的，或者是过去生态条件下选择压力的产物。然而，人类活动改变环境的快节奏导致了新的生态挑战，并使得很难区分进化适应和更快获得的行为反应，这些反应可能会或可能不会随着时间的推移而适应。了解这种可塑性是分析进化机制的基础，也是评估生活在受干扰栖息地的濒危灵长类动物未来的当务之急。 这项研究建立在一个独特的历史数据库，从长期的实地研究野生北方muriqui猴（Brachyteles hypoxanthus）在巴西东南部的大西洋森林，以评估生态变化如何驱动行为创新，并确定新的行为模式传播的社会途径内和组之间。北方穆里基是极度濒危的，281只被限制在957公顷的受保护森林片段中，研究种群占整个物种的25%以上。 在过去的27年里，种群数量增加了五倍，种群密度现在是该物种已知的最高密度。 以前对人口压力的行为调整包括从内聚到流动的群体模式的转变。 最近，尽管它们的生活方式是树栖的，但人口中最大的群体对地面的使用增加了20倍，其他三个较小的群体现在都在陆地上觅食。 来自陆地捕食者和病原体的更大风险意味着，这种在鼠的栖息地使用的变化是一个极端的表现，其生态位的整体扩张所必需的人口的增长在一个有限的区域。 在这个拥挤的人口的所有四个muriqui组的系统行为数据的收集，本研究将量化生态位扩张和社会过程的影响，新获得的行为模式是通过分散女性群体之间的扩散，随后在组内沿着建立社交网络传播。 该研究的学术价值包括它将为其他灵长类动物与地面使用相关的生态条件提供新的比较视角，以及它将为当代灵长类动物的适应潜力及其在快速变化的世界中的生存前景提供关键见解。除了其科学贡献，这项研究将为这一极度濒危物种的唯一长期研究提供必要的连续性，也是对任何灵长类动物进行的最长的实地研究之一。 它将有助于保存和保护北方穆斯林仅存的据点之一，并保持研究人员为巴西学生提供培训机会的长期传统。 合作研究和保护活动的既定记录，以及巴西能力建设的成功，扩大了本研究的更广泛影响，包括国际保护和教育议程。

Most comparative models of primate behavioral ecology assume that the behaviors of wild primates are adaptive, or are the products of selection pressures under ecological conditions in the past. Yet, the fast pace at which human activities alter the environment results in new ecological challenges and makes it difficult to distinguish evolutionary adaptations from more rapidly acquired behavioral responses that may or may not be adaptive over time. Understanding this plasticity is fundamental to analyses of evolutionary mechanisms and represents an urgent priority for assessments of the future of endangered primates living in disturbed habitats. This study builds on a unique historical database from the long-term field study of wild northern muriqui monkeys (Brachyteles hypoxanthus) in the Atlantic Forest of southeastern Brazil to evaluate how ecological change drives behavioral innovations and to identify the social pathways by which new behavior patterns spread within and between groups. The northern muriqui is critically endangered, and with 281 individuals confined to a 957-hectare protected forest fragment, the study population represents more than 25% of the entire species. During the past 27 years, the population has quintupled in size and the population's density is now the highest known for the species. Previous behavioral adjustments to population pressures have included shifts from cohesive to fluid grouping patterns. More recently, and despite their arboreal lifestyle, the largest group in the population has undergone a 20-fold increase in its use of the ground and all three of the other smaller groups now engage in terrestrial feeding. The greater risks from terrestrial predators and pathogens imply that this change in the muriquis' habitat use is an extreme manifestation of an overall expansion of their ecological niche necessitated by the population's growth within a confined area. With the collection of systematic behavioral data on all four muriqui groups in this crowded population, this study will quantify the ecological implications of niche expansion and the social processes by which newly acquired behavior patterns are diffused between groups by dispersing females and subsequently spread within groups along established social networks. The intellectual merits of the study include the new comparative perspectives it will provide into the ecological conditions associated with ground use in other primates, and the critical insights it will provide into the adaptive potentials of contemporary primates and their prospects for survival in a rapidly changing world.In addition to its scientific contributions, this study will provide essential continuity for the only long-term study on this critically endangered species and one of the longest-running field studies of any primate. It will contribute to the conservation and protection of one of the last remaining strongholds for northern muriquis, and maintain the researcher's longstanding tradition of providing training opportunities for Brazilian students. The established record of collaborative research and conservation activities, and success with capacity building in Brazil, extend the broader impacts of this study to include an international conservation and educational agenda.