Predictors of Colobus Abundance: How Populations Respond to Stress

生态学的一个基本问题是确定调节动物种群密度的因素。随着对濒危或受威胁物种制定明智的管理计划的需要，了解动物丰度决定因素的重要性日益增加。对于灵长类动物来说，这些问题至关重要，因为灵长类动物居住的热带森林正在经历快速的人为改造。然而，理解和预测决定灵长类动物数量的因素已被证明是极其困难的。对森林灵长类动物的大量研究已经揭示了种群密度在不同地点之间的高度差异，但很少有对解释这种差异的一般假设的直接测试。值得注意的例外是对叶食性灵长类动物的研究，其中可用叶片的蛋白质/纤维比率已被用于预测叶食性灵长类动物的生物量。在之前的NSF中，Colin Chapman展示了这种关系适用于小空间尺度，并且他能够预测乌干达Kibale国家公园内邻近的科洛拜猴种群的生物量。他还展示了高蛋白纤维比食物的饮食选择，并测试了两种可供选择的假设（colobine是能量有限的，或者受到特定矿物质的可用性的限制）。然而，为复杂的生物现象找到单一因素的解释，比如决定colobine丰度的决定因素，是不可能的。相反，最近的长期研究强调了多因素解释的重要性。因此，本项目将探索营养和寄生协同作用影响疣虫种群动态的可能性。将采取两种方法。首先，在1995年以来监测的森林碎片系统中，该项目将检验人口变化的规模是否与优质食品供应和寄生虫感染水平的变化有关。为了部分评估采用第二种方法时所做的假设，从粪便样本中分离出的应激激素水平将与人口变化的幅度有关。其次，通过对稳定种群的长期观察，以粪便中皮质醇代谢物的水平为指标，评估压力时期与食物短缺和/或寄生虫感染增加时期的对应程度。这项研究的广泛影响是多方面的。例如，这些信息将有助于为世界各地的食草灵长类动物制定明智的管理计划。资金还将用于Kibale的长期监测、Makerere大学生物野外站的基础设施建设、促进乌干达学生的培训和保护（已确定两名学生）、佛罗里达大学的研究生和本科生培训，以及通过协助制作自然电影（特别是与BBC合作）向公众传播这些信息。

A fundamental issue in ecology is determining factors that regulate the density of animal populations. The importance of understanding determinants of animal abundance has increased with the need to develop informed management plans for endangered or threatened species. With respect to primates, these issues are critical because tropical forests occupied by primates are undergoing rapid anthropogenic transformation. However, understanding and predicting factors that determine primate abundance has proven extremely difficult. Numerous studies of forest primates have revealed a high degree of inter-site variation in density, but there are few direct tests of general hypotheses proposed to account for this variation. Notable exceptions are studies of folivorous primates, where the protein/fiber ratio of available leaves has been used to predict folivorous primate biomass. In a previous NSF, Colin Chapman showed that this relationship applied to small spatial scales, and he was able to predict the biomass of neighboring populations of colobine monkeys inside Kibale National Park, Uganda. He also demonstrated diet selection for foods with high protein to fiber ratios and tested two alternative hypotheses (colobines are energy limited or restricted by the availability of particular minerals). However, finding single factor explanations for complex biological phenomena, like determinants of colobine abundance, is unlikely. Rather, recent long-term studies have highlighted the importance of multifactoral explanations. As a result, this current project will explore the possibility that nutrition and parasitism operate synergistically to influence colobus population dynamics. Two approaches will be taken. First, in a system of forest fragments monitored since 1995, this project will test if the size of population change is a function of changes in the availability of quality foods and the level of parasitic infections. To partially evaluate assumptions made when taking the second approach, levels of stress hormones, isolated from fecal samples, will be relate to the magnitude of population change. Secondly, using long-term observation of a stable population, the degree to which periods of stress, as indexed by levels of cortisol metabolites in fecal material, correspond to periods of food scarcity and/or increased parasite infections will be assessed. The broader impacts of this study are many. For example, this information will be useful in construction of informed management plans for folivorous primates around the world. Funding will also facilitate long-term monitoring in Kibale, building the infrastructure of Makerere University Biological Field Station, promoting Ugandan student training and conservation (2 students have been identified), graduate and undergraduate training at the University of Florida, and dissemination of this information to the public by assisting the development of nature films (particularly with the BBC).