Doctoral Dissertation Improvement: Are gelada loud calls "sexually-selected signals"?

狐猴和人类一样，生活在数量超过1000个个体的异常庞大的社会群体中。然而，与人类不同的是，在狐猴社会中占主导地位的雄性并不认识他们周围的其他雄性--甚至是他们每天遇到的雄性。这对争夺配偶的男性在社会和进化上(与健康相关)造成了一系列重大限制；主要是在参与代价高昂的竞争形式之前如何评估竞争对手。不使用个体识别进行评估的物种通常使用速记代理；即特定的物理特征或其他特征(“信号”)，这些特征有助于确定潜在竞争对手的竞争能力。虽然这种信号在灵长类动物中很少见，但在灵长类动物群落中发现的异常庞大的群体可能有利于它们通过一种被称为“性选择”的自然选择形式进化。由密歇根大学博士生Marcela Benitez(密歇根大学)在Jacinta Beehner博士的指导下进行的研究，将研究居住在埃塞俄比亚西米恩山国家公园的雄性Gleadas可能存在的一种信号--雄性显示器中使用的一种响亮的发声(即“大声叫喊”)。确定大声叫声是否是进化信号需要确定以下几点：(1)不同质量的雄性大声叫声存在差异，(2)雄性可以利用这些叫声来区分高质量和低质量的雄性，(3)雄性随后基于这些叫声进行挑战，以及(4)具有高质量叫声的雄性具有更高的适合度(繁殖成功)。为了应对这些预测，这项跨学科的研究将结合声学、实验、激素和观察分析，对已知的个体进行连续六年的跟踪。因此，这项研究是对理论上被称为“性选择信号”(即通过雄性和雄性生殖竞争进化而来的信号)与灵长类动物潜在健康影响的最全面的研究之一。这项研究是一个长期项目的一部分，该项目致力于通过合作研究和向埃塞俄比亚当地人和生态游客提供教育演示，在美国和埃塞俄比亚提高保护意识和科学教育。这位博士生Co-Pi是科学界代表性较低的群体的成员，她将把这项研究纳入她的双语网站，用于儿童教育推广，促进美国儿童与科学的接触。

Geladas (Theropithecus gelada), like humans, live in unusually large social groups with numbers that exceed 1000 individuals. Unlike humans, however, the dominant males in gelada society do not recognize other males around them - even males that they encounter on a daily basis. This creates a socially and evolutionarily (fitness-related) significant set of limitations for males competing for mates; mainly, how to assess rivals prior to engaging in costly forms of competition. Species that do not use individual recognition for assessment typically use short-hand proxies; i.e., particular physical features or other characteristics ("signals") which are useful for ascertaining the competitive abilities of potential rivals. Although such signals in primates are rare, the unusually large groups found in gelada society may have favored their evolution through a form of natural selection referred to as "sexual selection."Research by doctoral student Marcela Benitez (University of Michigan), under the supervision of Dr. Jacinta Beehner, will examine one such putative signal for male geladas living in the Simien Mountains National Park, Ethiopia - a loud vocalization used in male displays (i.e., "loud calls"). Establishing whether loud calls are evolved signals requires establishing the following: (1) that variation exists in loud calls across males of different quality, (2) that males can use these calls to distinguish between high and low quality males, (3) that males then base challenges on these calls, and (4) that males with high quality calls have higher fitness (reproductive success). To address these predictions, this interdisciplinary research will combine acoustic, experimental, hormonal, and observational analyses on known individuals that have been followed continuously for the past six years. As such, the research represents one of the most comprehensive studies of what are theoretically termed "sexually-selected signals" (i.e., those evolved through male-male reproductive competition) with potential fitness consequences in a primate.This research is part of a long-term project that is committed to increasing conservation awareness and scientific education, both in the U.S. and in Ethiopia, through collaborative research and educational presentations to local people and eco-tourists in Ethiopia. The doctoral student Co-PI, a member of an underrepresented group in science, will incorporate the research into her bilingual website for childhood educational outreach, promoting engagement with the sciences by US children.