Collaborative Research: Moving beyond causation: the ecological consequences of the terminal Pleistocene extinction of North American megafauna

世界各地的生态系统正在丧失生物多样性，当它导致大型物种（巨型动物）的丧失时，可能会对整个食物网以及这些生态系统的结构和功能产生重大后果。这项研究将考察过去大型动物的一次大灭绝，以了解其对生态系统的级联效应。大约13000年前，美洲的许多大型哺乳动物灭绝了。这项研究将研究这些大型食肉动物和食草动物从食物网中消失对剩余的植物和动物群落的影响。在这个很久以前的事件中看到的反应将用于发展与现代植物和动物群落变化相关的一般概念。该项目还将使化石数据更容易获取和解释，将改善博物馆的收藏，并将通过史密森学会开展的外展活动告知公众。这项工作还将为研究生和本科生提供研究经验，从而加强科学队伍。大约13,000年前数千万大型哺乳动物的灭绝对美洲生态系统的结构和功能的影响将被研究，以解决四个问题：大型哺乳动物的灭绝如何影响更新世末期的整体群落结构和物种相互作用；幸存的物种是否变得更加丰富或改变了它们的地理分布？在灭绝中幸存下来的物种在形态上发生了什么变化，如果有的话；幸存的物种是否为了应对巨型动物的灭绝而改变了它们的饮食生态位？在灭绝事件前后幸存哺乳动物的丰度、分布、饮食和形态模式将被表征。利用化石数据库汇编的发生信息，通过测量化石的四肢和臼齿来确定形态和大小，通过稳定同位素分析来确定饮食。这些数据将与利用花粉数据库以及区域和全球温度记录重建的植物群落相结合。通过描述陆地生态系统在人类历史上的一个重要时刻是如何受到人类影响的，将为理解当代营养退化建立一个重要的生态基线。

Biodiversity is being lost from ecosystems worldwide, and when it results in the loss of large-bodied species (megafauna) it can have major consequences for entire food webs, and the structure and function of those ecosystems. This study will examine a past major extinction of megafauna in order to understand the cascading effects on ecosystems. About 13,000 years ago many species of large mammals in the Americas became extinct. This research will examine the consequences of the loss of these large carnivores and herbivores from the food web to the remaining plant and animal communities. The responses seen at this long-ago event will be used to develop general concepts relevant to modern-day changes in plant and animal communities. This project will also make fossil data more easily accessible and interpretable, will improve museum collections, and will inform the public through outreach activities conducted by the Smithsonian Institution. This work will also provide graduate and undergraduate students with research experience that will strengthen the scientific workforce. The consequences of the loss of tens of millions of large-bodied mammals about 13,000 years ago on the structure and functioning of ecosystems in the Americas will be examined in order to address four questions: How did the extinction of large-bodied mammals influence overall community structure and species interactions at the terminal Pleistocene; Did surviving species become more abundant or change their geographic distribution; What changes in morphology, if any, occurred in species that survived the extinction; Did surviving species alter their dietary niche in response to the extinction of megafauna? Patterns of abundance, distribution, diet and morphology in the surviving mammals both before and after the extinction event will be characterized. Using occurrence information from fossil database compilations, morphology and size will be determined by measuring fossil limbs and molars, and diet by using stable isotope analysis. These data will be integrated with reconstructions of vegetative communities using pollen databases and regional and global temperature records. An important ecological baseline for the understanding of contemporary trophic downgrading will be established by characterizing how terrestrial ecosystems were influenced by humans at an important point in human history.