Collaborative Research: Causes and Consequences of Vocal Variation in a Howler Monkey (Alouatta spp.) Hybrid Zone: An Integrated Behavioral, Morphological and Genetic Approach

杂交带通常包括在相似的生态和社会条件下生活的各种分类和遗传上不同的个体。因此，杂交区提供了独特的机会来分离动物变异的内在和外在原因。此外，由于各种动物都处于直接竞争中，杂交区也是研究竞争能力的理想场所。这个项目的重点是两种吼叫猴，Alouatta palliata和a . pigra，它们在墨西哥南部的一个小地区杂交，叫声不同。这项研究建立在先前的杂交区形态学和遗传采样的基础上，并解决了两个主要问题：1)是什么导致了白斑单脚猿、pigra单脚猿和杂交单脚猿之间的声音变异？2)不同的发声方式如何影响混合区域的竞争能力？为了解决这些问题，该项目将分子、形态、行为和声学数据与回放实验相结合。通过比较纯种和杂交雄性的遗传背景、形态、位置和社会环境，将发现声音差异的来源。回放实验涉及雄性和雌性，并揭示了雄性觉得吓人或雌性觉得有吸引力的叫声类型（或两者兼而有之）。本研究探讨了灵长类动物发声的直接因素和最终因素，性选择如何构成混合和基因流动，以及发声的差异如何影响性选择。该项目是高度协作的，将在许多层面加强研究联系；密歇根大学各系之间，密歇根大学和俄亥俄州立大学之间，以及美国大学和墨西哥韦拉克鲁斯纳大学之间的国际关系。除了为墨西哥和美国学生提供大量培训外，该项目还将通过针对杂交区域内学龄儿童的教育研讨会，直接促进保护工作。此外，该地区的长期研究以及墨西哥研究人员和学生的参与将促进灵长类动物的研究和保护，墨西哥是一个对灵长类动物和其他新热带分类群具有高度生物地理重要性的国家。

Hybrid zones typically encompass a variety of taxonomically and genetically distinct individuals living under similar ecological and social conditions. Thus, hybrid zones represent unique opportunities to separate intrinsic and extrinsic causes of variation among animals. Furthermore, because a variety of animals are in direct competition, hybrid zones are also ideal locations for studies of competitive ability. This project focuses on two species of howler monkeys, Alouatta palliata and A. pigra, with different vocalizationsthat hybridize in a small region in southern Mexico. The research builds on previous morphological and genetic sampling of the hybrid zone and addresses two main questions: 1) what causes vocal variation among A. palliata, A. pigra, and hybrids? and, 2) how do different vocalizations impact competitive ability in the hybrid zone? To address these questions the project integrates molecular, morphological, behavioral, and acoustic data with playback experiments. Sources of vocal differences will be uncovered by comparing vocalizations among purebred and hybrid males to their genetic background, morphology, location, and social setting. The playback experiments involve both males and females and reveals the types of calls that males find intimidating or females find attractive (or both). The study examines the proximate and ultimate factors shaping primate vocalizations, how sexual selection structures admixture and gene flow, and how differences in vocalizations affect sexual selection. The project is highly collaborative and will strengthen research ties at many levels; between departments at the University of Michigan, between the University of Michigan and Ohio State University, and internationally between US universities and the Universidad Veracruzana in Mexico. In addition to providing considerable training to Mexican and US students, the project will directly benefit conservation through an educational workshop directed to school-age children within the area of hybridization. Furthermore, the presence of a long-term study in the region and the inclusion of Mexican researchers and students will promote primate studies and conservation in Mexico, a country of high biogeographic importance for primates and other Neotropical taxa.