Doctoral Dissertation Improvement: Functions and Consequences of Intergroup Aggression in Tufted Capuchin Monkeys

灵长类动物行为进化的现有模型表明，群体间竞争的强度强烈地影响着灵长类动物社会性的基本方面，包括雌性和雌性之间的社会关系。尽管在许多物种中都发现了群体之间的相遇，并且经常被描述为攻击性，但人们对这些相互作用的功能和后果知之甚少。群体之间相遇时的攻击行为被认为有助于保护有限的资源或交配机会。本研究将在阿根廷伊瓜苏国家公园系统地研究簇尾卷尾猴（Cebus apella）群体间攻击的这些可能功能。研究人员将同时跟踪多个社会群体，记录个体参与群体间接触的模式，群体间攻击的总体强度，以及可能影响这些互动的几个因素，包括发情的雌性和脆弱的婴儿的存在，或靠近可争夺的食物资源。此外，研究人员将利用生态和行为数据的结合，测试更具侵略性的成功群体是否能在重叠区域获得或保留更优质的领土和资源。群体之间因遭遇和统治而获得或失去食物的情况，将与群体内成员之间的侵略行为产生的类似后果进行比较。为了对特定的假设进行控制测试，研究人员将通过声音回放实验来模拟另一个社会群体的存在。这些实验将在人工控制的资源附近进行，以独立操纵明显遭遇的社会和生态背景。以往对非人类灵长类动物群体间攻击的研究无法收集到详细的行为和生态数据，以区分群体间攻击的各种假设功能。这个研究项目将通过系统地检查配偶和关键食物资源竞争的重要性来解决这些差距。这项研究还将用于与以前研究过的秘鲁人口进行比较，这些人口表现出较少的群体间攻击，从而可以直接检查资源分配和可得性方面的人口差异对群体间竞争的影响。该项目将为阿根廷学生、瓜拉尼社区成员以及可能的美国大学生志愿者提供就业和培训。

Current models of the evolution of primate behavior suggest that the strength of between-group competition strongly affects fundamental aspects of primate sociality, including female-female and male-female social relationships. Although encounters between groups are found in many species and are often described as aggressive, the functions and consequences of these interactions remain poorly understood. Aggressive behavior during encounters between groups is thought to help defend access to limiting resources or mating opportunities. This study will systematically examine these possible functions of between-group aggression in tufted capuchin monkeys (Cebus apella) at Iguazu National Park, Argentina. The researchers will follow multiple social groups simultaneously and record patterns of individual participation in intergroup encounters, the overall intensity of intergroup aggression, and several factors that may affect these interactions, including the presence of estrous females and vulnerable infants or the proximity to contestable food resources. In addition, the researchers will test if more aggressively successful groups gain or retain access to better quality territories and resources in areas of overlap, using a combination of ecological and behavioral data. The loss or gain of food from encounters and dominance between groups will be compared to similar consequences of aggression among members within a group. To make controlled tests of particular hypotheses, the researchers will simulate the presence of another social group with vocal playback experiments. These experiments will occur near artificially-controlled resources to independently manipulate the social and ecological context of apparent encounters.Previous studies of intergroup aggression in non-human primates have been unable to collect the detailed behavioral and ecological data necessary to distinguish among all the various hypothesized functions of between-group aggression. This research project will address these gaps by systematically examining the importance of competition for mates and critical food resources. The study will also be used to compare with previously studied Peruvian populations that exhibit reduced intergroup aggression, thereby allowing direct examination of the influence of population differences in resource distribution and availability on between-group competition. The project will provide employment and training for Argentine students, members of the Guarani community, and possibly U.S. undergraduate volunteers.