Collaborative Research: Genetic mechanisms of conditional-expression and trait exaggeration in weapons of sexual selection

动物产生了令人眼花缭乱的各种装饰品和武器，这些装饰品和武器在雄性与雌性的生殖途径的竞争中发挥了作用。这些结构中最精细的有两个共同特征：不成比例的生长产生夸大的特征尺寸，以及比其他非性别选择的结构的生长对营养更敏感(例如，驼鹿或麋鹿的鹿角在最大的公牛身上达到极大的尺寸，鹿角的生长对动物的营养状态特别敏感)。尽管人们对这些性选择特征的进化非常感兴趣，但几乎对导致不成比例/夸张生长的基因或发育机制，或将营养与性状生长量联系在一起的机制，几乎一无所知。这一建议解决了在理解装饰品和性选择武器的进化潜力方面的一个根本差距：哪些基因和发育/生理过程是营养依赖型表达和夸大生长的基础？这个项目的前提是，要了解这些结构的演变，需要探索它们如何发展的细节。长期目标是了解生理和发育如何与环境相互作用，以产生形态和行为表型的多样性。其目的是确定负责产生夸大的武器生长和营养依赖的表型可塑性的基因和相关的生理途径。研究人员将(1)测试产生营养依赖性表达的机制是否与产生夸大生长的机制相同，以及(2)比较三种甲虫谱系中两种武器(角和下颌骨)的机制，这些甲虫代表三个独立的扩大雄性武器的起源(屎甲虫、犀牛甲虫和鹿角甲虫)。所采用的综合方法将揭示与动物的营养依赖表型可塑性有关的生理和发育途径，并将提供迄今最全面的研究之一，将男性状况的变化与性选择特征的表达联系起来--这是当前性别选择理论的核心原则。一个核心目标是对年轻科学家进行遗传学、发育、生理学和进化论方面的交叉培训。参与此项目的博士后和学生将在所有三个实验中花费大量时间积极学习技术，并与所有三个PI进行互动和协作。PIs致力于在研究过程的各个方面培训本科生，并将纳入包容多样性的科学创新教学方法；这一系统的本质本身就适合以学习者为中心的调查。这些重点物种是外展活动的绝佳资源，PI将在旨在加强K-12学生以及非正式科学教育环境中STEM学习的教育计划中使用这些动物，包括访问西澳大利亚和蒙大拿州当地的学校教室，支持西德克萨斯州立大学昆虫博物馆，并帮助建立一个新的蒙大拿州昆虫动物园。

Animals produce a bewildering diversity of ornaments and weapons that function in male contests over reproductive access to females. Two characteristics are common in the most elaborate of these structures: disproportionate growth yielding exaggerated trait sizes, and growth that is more sensitive to nutrition than is the growth of other, non-sexually-selected, structures (e.g. antlers in moose or elk reach extreme sizes in the largest bulls, and antler growth is especially sensitive to the nutritional state of the animal). Despite intense interest in the evolution of these sexually selected traits, almost nothing is known of the genes or the developmental mechanisms responsible for disproportionate/ exaggerated growth, or of the mechanisms linking nutrition with the amount of trait growth. This proposal addresses a fundamental gap in understanding the evolutionary potential of ornaments and weapons of sexual selection: What are the genes and developmental/ physiological processes that underlie nutrition-dependent expression and exaggerated growth? The premise for this project is that to understand the evolution of these structures requires exploration of the details of how they develop. The long-term goal is to understand how physiology and development interact with the environment to generate diversity in morphological and behavioral phenotypes. The objectives are to identify genes and associated physiological pathways responsible for generating exaggerated weapon growth, and nutrition-dependent phenotypic plasticity. The investigators will (1) test whether the mechanisms generating nutrition-dependent expression are the same as those generating exaggerated growth, and (2) compare these mechanisms for two weapons (horns & mandibles) in three lineages of beetle representing three independent origins of enlarged male weapons (dung beetles, rhinoceros beetles, & stag beetles). The integrative approach utilized will shed light on physiological and developmental pathways involved with nutrition-dependent phenotypic plasticity in animals generally, and will provide one of the most comprehensive studies to date linking variation in male condition with the expression of sexually selected traits - a central tenet of current theories of sexual selection. A core objective is the cross-training of young scientists in genetics, development, physiology and evolution. The postdoc and students involved with this project will spend extensive periods in all three labs actively learning techniques and interacting and collaborating with all three PIs. The PIs are committed to training undergraduates in all aspects of the research process, and will incorporate innovative teaching methods in science that embrace diversity; the very nature of this system lends itself to learner-centered investigations. The focal species are a fantastic resource for outreach activities and the PIs will use these animals in educational programs designed to enhance STEM learning in K-12 students as well as in informal science education environments, including visiting local school classrooms in both WA and MT, supporting the WSU insect museum, and aiding with a new Montana insect zoo.