Fitness Consequences of Sexually Selected Acoustical Signaling in American Bison

现在很清楚，性选择（选择增加交配成功率的性状）导致了雄性的性二型属性的进化。 无论是在雄性竞争还是雌性择偶的背景下，这些特征中的许多都是包含有关配偶质量信息的信号。 对无脊椎动物和小型脊椎动物的研究表明，接收者往往会评估这些信号，以便选择最大限度地提高繁殖成功率的策略。 关于信号评估如何在大型哺乳动物中起作用的知之甚少，其中必须在繁殖季节的过程中同时评估多个和变化的信号。 本研究的目的是调查雄性野牛的波纹发声的产生和评估，这是野牛繁殖季节最显著的标志。 目的是阐明波纹信号在繁殖雄性成功中的作用。 核心假设是，风箱中包含有用的信息，其他野牛可以评估并利用它们的优势。 这一假设是基于强有力的初步研究结果，表明一些波纹管的声学特征反映了信号男性的质量。 这项研究的一个必要的先决条件是了解繁殖成功如何与交配性能和其他野牛可能用来评估雄性质量的属性。 因此，该项目的一个组成部分将是使用分子技术来确定遗传亲子关系，以与雄性交配行为进行比较。 野牛将在尼奥布拉拉堡国家野生动物保护区进行研究，那里所有的成年野牛都被单独标记，开阔的草原地形使人们能够不断监测繁殖行为。 一个由五名合作者组成的多学科团队将对遗传亲子关系、声学和行为内分泌学进行实验室分析，以补充行为观察。 从黎明到黄昏的观察将记录繁殖行为，遗传亲子关系分析将为所有小牛分配母性和父权。 吼叫将被记录从占主导地位的和从属的男性，和录音进行分析，以比较声学特征与信号质量的措施（繁殖成功，竞争能力，条件，生理状态）和动机（倾向于女性的发情条件，具有挑战性的男性数量）。 将在夜间进行回放实验，以评估雄性对合成风箱声学特征的反应。 粪便样本将用于测量雄性和应激激素（与支配和攻击相关）以及雌性激素（以确定激素发情期）。 研究结果将为类似物种提供见解，其中发声在繁殖中发挥作用。 本科生和研究生的实地和实验室参与将提供宝贵的学习经验，并为未来的科学职业做好准备。 最后，野牛生殖生物学的信息可以应用于保护这个关键物种和美国西部的象征。

It is now clear that sexual selection (selection for traits that increase mating success) has led to the evolution of sexually dimorphic attributes in males. Whether in the context of male-male contests or female mate choice, many of these traits act as signals that contain information about mate quality. Studies of invertebrates and small vertebrates have revealed that such signals are often assessed by receivers so as to choose tactics that maximize reproductive success. Little is known regarding how signal assessment works in large mammals, in which multiple and changing signals must be evaluated concurrently over the course of the breeding season. The goal of this research is to investigate the production and assessment of the bellow vocalization of male bison, which is the most conspicuous hallmark of the bison breeding season. The aim is to clarify the role of the bellow signal in the reproductive success of breeding males. The central hypothesis is that useful information is contained in bellows that other bison can evaluate and use to their advantage. This hypothesis is based on strong preliminary findings that indicate that a number of bellow acoustical features reflect the quality of the signaling male. A necessary prerequisite to this study is an understanding of how reproductive success relates to mating performance and attributes that other bison may use to assess male quality. Therefore, an integral component of this project will be the use of molecular techniques to determine genetic parentage for comparison with male mating behavior. Bison will be studied at Fort Niobrara National Wildlife Refuge where all adults are individually marked and open grassland terrain enables constant surveillance of breeding behavior. A multidisciplinary team of five collaborators will perform the laboratory analyses for genetic parentage, acoustics, and behavioral endocrinology that will complement behavioral observations. Dawn-to-dusk observations will document breeding behavior, and genetic parentage analyses will assign maternity and paternity to all calves. Bellowing will be recorded from dominant and subordinate males, and recordings analyzed to compare acoustical features with measures of signaler quality (reproductive success, competitive ability, condition, physiological state) and motivation (estrous condition of tended female, number of challenging males). Playback experiments will be conducted at night to evaluate the response of males to the acoustical features of synthesized bellows. Fecal samples will be used to measure male sex and stress hormones (associated with dominance and aggression), and female sex hormones (to determine hormonal estrus). The results will provide insights into similar species in which vocalizations play a role in breeding. Field and lab participation by undergraduate and graduate students will offer valuable learning experiences and preparation for future careers in science. Finally, information obtained on bison reproductive biology can be applied to the conservation of this keystone species and symbol of the American West.