CAREER: Environmental Change and Extinction on the Mammoth Steppe

在最后一个冰河时期，北极的大部分地区覆盖着多样化的、多产的草原，这些草原供养着大量的猛犸象、野牛和其他大型食草动物。这片“猛犸象草原”栖息地在1万年前消失了，随之消失的还有生活在那里的巨型动物，但它们的灭绝是栖息地丧失的原因还是结果，目前还不得而知。在现代生态系统中，大型食草动物在维持草原健康方面发挥着重要作用，但它们在冰河时代景观中所起的作用尚不清楚。该项目将重建连接亚洲和北美的冰河陆桥白令陆桥的生态史前史，以确定物种灭绝、环境变化和栖息地丧失的时间和性质。食草动物仍然是当今最受威胁的动物之一，因此了解“冰河时代的塞伦盖蒂”可以帮助管理当今地球上最大的动物，并可能为了解本地食草动物在变暖的北极所扮演的角色提供见解。该项目还将为从中学到研究生院的学生（包括大多数第一代大学生）提供教育、指导和培训，他们将在实地和实验室中合作完成该项目。项目成果将被纳入学生设计的冰河时代虚拟现实游戏中，并由新培训的大学生“科学大使”在中学实施，为农村、低收入社区的学生提供尖端的科学体验。这项研究将在几个受保护的北极地区进行，包括白令陆桥国家保护区、弗兰格尔岛保护区（联合国教科文组织世界遗产，也是地球上最后一个已知的长毛象所在地）和更新世公园，更新世公园也将从这些研究结果中受益。该项目旨在了解猛犸象草原中大型食草动物、植被和环境变化之间的关系，使用新的高分辨率、多代理记录，包括来自白令陆桥西部和东部四个地点的大型食草动物崩溃、古植被、火灾和气候，包括地球上最后确定的长毛猛犸象的位置。方法包括传统（如花粉、木炭）和新兴（古DNA、分子古气候代用物）方法的混合，这些方法将为第四纪环境的跨学科培训和教育提供机会。这些最先进的古环境重建将使一个由研究生、本科生和高中生组成的合作团队沉浸在基于数据的冰河时代虚拟现实体验为基础的、跨学科的合作学习和研究经验中，目标是扩大农村和第一代大学生对STEM的参与。结果将测试和完善关于生态背景和巨型动物灭绝后果的假设，这对解释古记录和在变暖的世界中保护现代关键物种具有重要意义。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

During the last ice age, large parts of the Arctic were covered in diverse, productive grasslands that supported large populations of mammoths, bison, and other large grazers. This "mammoth steppe" habitat disappeared by 10,000 years ago, along with the megafauna who lived there, but it is still unknown whether their extinction was a cause or an effect of habitat loss. Large herbivores play important roles in maintaining the health of grasslands in modern ecosystems, but the role they played in ice age landscapes is less clear. This project will reconstruct ecological prehistory across Beringia, the ice age land bridge that connected Asia and North America, to establish the timing and nature of extinction, environmental change, and habitat loss. Herbivores remain some of the most threatened animals today, so understanding the "Serengeti of the ice age" can help in the management of Earth's largest animals today, and may provide insights into the role native grazers play in a warming Arctic. This project also will provide education, mentoring, and training for students from middle school to graduate school (including a majority first-generation college student population), who will work collaboratively on this project in the field and in the lab. Project results will be incorporated into a student-designed ice age virtual reality game, and implemented in middle schools by newly trained college student "science ambassadors" to provide cutting-edge science experiences for students in rural, low-income, communities. The research will be conducted in several protected Arctic locations, including Bering Land Bridge National Reserve, Wrangel Island Reserve (a UNESCO World Heritage site and the last known location of woolly mammoths on Earth), and Pleistocene Park, which also will benefit from these results. This project aims to understand the relationship between megaherbivores, vegetation, and environmental change in the mammoth steppe, using new high-resolution, multi-proxy records of megaherbivore collapse, paleovegetation, fire, and climate, from four sites in western and eastern Beringia, including the last dated location of woolly mammoths on Earth. Methods include a mix of traditional (e.g., pollen, charcoal) and emerging (ancient DNA, molecular paleoclimate proxies) approaches that will provide opportunities for interdisciplinary training and education in Quaternary environments. These state-of-the-art paleoenvironmental reconstructions will immerse a cooperative team of graduate, undergraduate, and high school students in field-based, cross-disciplinary cooperative learning and research experiences based around data-informed ice age virtual reality experiences for middle schoolers, with a goal of broadening participation of rural and first-generation college students in STEM. Results will test and refine hypotheses for the ecological context and consequences of megafaunal extinctions, which have implications for interpreting paleorecords and the conservation of modern keystone species in a warming world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.