Using an eco-evolutionary framework to study Cenozoic (66 Ma - present) mammal responses to abiotic and biotic perturbation

这项提议旨在利用西半球哺乳动物的现代和化石记录来了解导致现代群落出现的条件，各种驱动因素如何促进哺乳动物群落的进化，并制定哺乳动物对生物和非生物扰动的反应基线。*一个物种在生态群落中的生态位或功能是它们生活在哪里、与哪些物种互动、它们进化的“寿命”(即从起源到灭绝的时间)以及物种形成和灭绝的速度和模式(即一个物种可能灭绝还是产生新物种)的重要决定因素。在我的实验室里，我们开发了新的方法来推断生态位，并利用现有的方法来解释生态位如何塑造了过去和现在的哺乳动物群体的多样性。然后，我们将使用生态位信息来了解现代哺乳动物群落是如何形成并塑造哺乳动物对全球变化的反应的。*我们将具体讨论生态位差异在决定食肉动物(猫、狗、熊及其近亲)相对于已灭绝的食肉哺乳动物(克龙牙)成功方面的作用。因此，我们将回答“是什么进化条件导致了现代食肉哺乳动物的聚集？”并确定Creodont生态位在其灭绝敏感性中的作用。生态轴的变化是物种对扰动做出反应的重要手段。我们将利用碳、氮和氧的稳定同位素开发鹿角，这是一种与骨骼成分相似的硬组织，作为生态指标。鹿角每年都会脱落，因此可以提供鹿及其近亲生态位轴变化的高分辨率记录。然后，我们将使用驯鹿鹿角来了解驯鹿生态位如何从第四纪晚期转变为现代，利用加拿大自然博物馆的藏品。经典生态位理论预测，物种被塞进生态位空间的方式反映了群落的组装机制。最近的研究表明，在构建哺乳动物群落时，历史因素比邻近因素更重要。我们将开发一种新的西半球哺乳动物化石和现存哺乳动物的系统发育，这将促进对现在和过去哺乳动物动物群的系统发育和功能多样性变化的研究。我们将具体使用系统发育方法来测试物种交换(即扩散或生物交换)和进化模式(即稳定选择、布朗运动)如何导致过去和现在西半球热带和温带哺乳动物组合的系统发育和功能结构的差异。*要对全球变化的结果做出有用的预测，需要整合现代观测、预测和化石数据。我们的工作产生了对全球变化影响的预测，直接解决了灭绝和进化的作用。

This proposal aims to use the modern and fossil record of Western Hemisphere mammals to understand the conditions that have led to the emergence of modern communities, how various drivers have contributed to the evolution of mammal communities, and to develop a baseline for mammal response to biotic and abiotic perturbation. ******A species' niche or function in an ecological community is an important determinant of where they live, the species with which they interact, their evolutionary “life spans” (i.e., time from origination to extinction), and rates and patterns of speciation and extinction (i.e., whether a species may go extinct or give rise to new species). In my lab, we develop new methods for inferring niches and employ existing methods to explain how niches have shaped the diversity of past and present mammal groups. We then use niche information to understand how modern mammal communities formed and have shaped mammal responses to global change.******We will specifically address the role of niche differences in determining the success of Carnivora (cats, dogs, bears, and their relatives) over extinct carnivorous mammals (Creodonts). We will thus answer “what evolutionary conditions led to modern carnivorous mammal assemblages?” and determine the role of creodont niches in their extinction susceptibility.******Changes in niche axes are important means by which species respond to perturbation. We will develop antler, a hard tissue with similar composition as bone, as ecological indicators using stable isotopes of carbon, nitrogen, and oxygen. Antlers are shed every year and may therefore provide a high-resolution record of niche axis change in deer and their relatives. We will then use caribou antlers to understand how caribou niches have changed from the late Quaternary to modern using collections at the Canadian Museum of Nature.******Classical niche theory predicts that the ways in which species are packed into niche space reflect community assembly mechanisms. Recent studies suggest historical factors are more important than proximate factors in structuring mammal communities. We will develop a new combined fossil and extant mammal dated phylogeny for Western Hemisphere mammals, which will feed studies of phylogenetic and functional diversity change in both present and past mammal faunas. We will specifically use phylogenetic methods to test how species exchange (i.e., dispersal or biotic interchange) and evolutionary mode (i.e., stabilizing selection, Brownian Motion) have contributed to differences in the phylogenetic and functional structure of Western Hemisphere tropical and temperate mammal assemblages in the past and present. ******Generating useful predictions for the outcome of global change requires the integration of modern observation, forecasting, and fossil data. Our work generates predictions for the impact of global change that directly addresses the role of extinction and evolution.