Ecological Mechanisms Underlying Differences in Agonistic behavior Among Females in Two Cercopithecine Primate Species

本研究项目将阐明导致黑尾猴（Cercopithecus aethiops）和赤尾猴（Erythrocebus patas）群体内雌性竞争关系差异的生态机制。尽管它们的同乡关系和亲缘关系密切，但雌长尾鼠和野田鼠在雌性竞争关系的表达上存在差异：雌长尾鼠具有稳定的线性优势等级，而雌野田鼠具有不太稳定的非线性优势等级。尽管理论和经验证据表明，这些行为差异最终可以通过食物资源质量的差异来解释，但导致灵长类动物雌性竞争行为差异的食物的关键特征仍然让我们困惑。食物的空间分布一直被认为是关键特征的主要竞争者。然而，最近对这一种群的研究表明，关键特征实际上是取食地点的耗竭时间，这是由食物大小和处理时间决定的。尽管帕塔的食物比马尾草的食物间隔更广，但它们的消耗时间也更短。更能说明问题的是，当黑尾草在两个相邻的栖息地觅食时，它们所吃的食物在空间分布上没有差异，但在消耗时间上存在差异，并且在消耗时间较长的栖息地中，竞争相互作用发生得更频繁。消耗缓慢的食物比消耗迅速的食物更容易被窃取。本项目将阐明取食地点耗竭时间和食物间距离在决定雌性交配关系中马尾鼠和野马尾鼠差异中的作用。在一系列野外实验中，系统地操纵取食地点耗竭时间和食物间距离，以确定黑尾鼠和野田鼠可篡夺性的时空阈值水平。然后将实验中获得的可篡夺性阈值与野生食物的食物间距离和消耗时间进行比较，以评估阈值是否可以预测自然条件下对食物的竞争行为。

This research project will elucidate the ecological mechanisms that are ultimately responsible for differences between vervet monkeys (Cercopithecus aethiops) and patas monkeys (Erythrocebus patas) in female agonistic relationships within groups. Despite their sympatry and phylogenetically close relationship, vervets and patas differ in their expression of female competitive relationships: female vervets have stable, linear dominance hierarchies whereas female patas have less stable, non-linear dominance hierarchies. Although theoretical and empirical evidence suggests that these behavioral differences can be explained ultimately by differences in some quality of food resources, the critical characteristic of food that is responsible for variation in female competitive behavior in primates still eludes us. Spatial distribution of foods has long been the leading contender as the critical characteristic. Recent research on this population of vervets and patas suggests, however, that the critical characteristic is actually feeding site depletion time, which is determined by food size and handling time. Although the foods of patas are more widely spaced than the foods of vervets, they also have shorter depletion times. More revealing is that when vervets forage in two adjacent habitats, they eat foods that do not differ in their spatial distribution but that do differ in their depletion times, and agonistic interactions occur more frequently in the habitat with foods having the longer depletion times. Foods that are depleted slowly may be easier to usurp than foods that are depleted quickly. This project will clarify the roles of feeding site depletion time and interfood distance in determining the differences between vervets and patas in female agonistic relationships. Feeding site depletion time and interfood distance will be systematically manipulated in a series of field experiments to determine the temporal and spatial threshold levels of usurpability for vervets and patas. The thresholds of usurpability obtained in the experiments will then be compared to interfood distances and depletion times of wild foods to assess whether the thresholds can predict agonistic behavior over foods under natural conditions.