Doctoral Dissertation Improvement: Nutritional ecology of Mexican black howler monkeys: The role of nutrient mixing, plant secondary metabolites, and behavioral flexibility

许多灵长类物种全年都在利用低质量和难以加工的资源，或者在一年中食物有限的时候作为备用食物。除了解剖学上的专业化，灵长类还开发了行为和认知解决方案，在利用低质量食物时，有助于提高觅食效率或减少能量需求。最优觅食理论已经被用来解释灵长类的觅食行为，并预测个体的食物选择最好地描述为能量摄入的最大化。然而，根据最近的营养生态学模型，营养混合框架可能会为灵长类的觅食策略提供更好的解释。这项研究考察了Alouatta pgra的营养生态，这是一种濒临灭绝的灵长类动物，以低质量的资源为食，但与密切相关的物种相比，其特点是生长速度快，繁殖产量高。具体地说，通过整合营养、能量、生态和行为数据，这项研究调查了食物和补丁的选择、食物采食率、植物资源的营养成分、食物可获得性的季节性变化、繁殖的营养需求以及群体内摄食竞争等因素如何影响生活在墨西哥南部的两个相邻群体的雄性和雌性咆哮猴的觅食策略。三个模型的解释能力将使用营养学的几何框架进行测试。这将通过对被标记的个体进行详细的行为观察、植被评估和确定群体家庭范围内的食物可获得性，以及对从喂食树收集的食物进行植物化学分析来实现。虽然有关于咆哮猴觅食生态的数据，但对影响雄性和雌性食物选择的准确营养因素知之甚少。通过为每种重点动物构建完整的饮食结构，并使用营养显式模型分析个体觅食决策，这项研究提供了对营养平衡在评估灵长类食物选择和决策中的重要性的关键洞察。该项目还将为圈养灵长类动物的管理提供有价值的营养信息，加强墨西哥和美国大学之间的合作，并为包括理科女生在内的墨西哥本科生提供培训机会。

Many primate species exploit low quality and difficult to process resources year-round or as fallback foods during food-limited times of the year. In addition to anatomical specializations, primates have developed behavioral and cognitive solutions that serve to increase foraging efficiency or reduce energetic requirements when exploiting low quality foods. Optimal Foraging Theory has been used to explain foraging behavior in primates, and predicts that individual food choice is best described in terms of maximization of energy intake. However, according to recent nutritional ecology models, a nutrient mixing framework may provide a stronger explanation of primate foraging strategies. This study examines the nutritional ecology of Alouatta pigra, an endangered primate that feeds on low quality resources and yet is characterized by rapid growth rates and a high reproductive output compared to closely related species. Specifically, by integrating nutritional, energetic, ecological, and behavioral data, this research investigates how factors such as food and patch choice, food intake rates, the nutritional composition of plant resources, seasonal changes in food availability, the nutritional requirements of reproduction, and within-group feeding competition affect male and female foraging strategies in two neighboring groups of black howler monkeys living in Southern Mexico. The explanatory power of three models will be tested using a Geometric Framework for nutrition. This will be accomplished by detailed behavioral observations of marked individuals; vegetation assessments and determination of food availability in the groups' home ranges; and phytochemical analyses of foods collected from feeding trees.While there are data on howler monkey feeding ecology, the precise nutritional factors affecting male and female food choices are poorly understood. By constructing complete dietary profiles for each focal animal, and analyzing individual foraging decisions using a nutritionally explicit model, this research provides critical insight into the importance of nutrient balancing in assessing primate food choice and decision-making. The project also will provide valuable nutritional information for the management of captive primates, strengthen partnerships between Mexican and US universities, and offer training opportunities for Mexican undergraduates, including female students in science.