Collaborative Research: Land Bridges, Ice-Free Corridors, and Biome Shifts: Impacts on the Evolution and Extinction of Horses in Ice-Age Beringia

标题：大陆桥、无冰走廊和生物群变化：对冰河时代柏林马匹进化和灭绝的影响这项研究问：对于维持遗传多样性、影响进化变化和减轻灭绝风险，北极大型哺乳动物种群之间的联系有多重要？哪些类型的障碍影响了这种联系，这些障碍对基因流动的渗透性有多大？PIs将研究居住在冰河时代Beringia(亚洲和北美之间的生物地理连接点)的卡巴马如何受到三种不同生物地理障碍/走廊(1.白令海峡/白令陆桥，控制欧亚大陆和阿拉斯加之间的扩散和基因流动；2.无冰走廊，控制育空地区和下48个州之间的基因流动；以及3.在冰河时代最后30,000年期间周期性地扰乱猛犸象-草原生态系统空间连续性的生物群落变化的影响。这项研究将使用新的古基因组和古环境数据来评估每一种假定的基因流动障碍对北极冰河时代马的丰度、分布和进化轨迹的影响。这些结果将为环境变化和人口分散在确定物种灭绝风险中所扮演的角色提供新的见解，并有助于预测正在进行的环境变化将如何影响北极生态系统。该项目将在快速发展的古遗传学领域取得进展，进一步推动古基因组生态学这一全新学科的发展。更广泛的影响计划侧重于：a)为研究生提供研究和专业发展机会，b)为有志成为STEM高中教师的本科生提供新的培训机会，c)与阿拉斯加农村的土著社区进行接触，以及d)与亚肯色州费尔班克斯的K-12学生进行接触。在每个暑假结束时，职前教师、研究生和私人教师将制作一个9-12年级的探究活动模块，与当地学校分享。最后，PI将参与专业和公共讨论，并将结果用于媒体制作。这是一项结合尖端古基因组学技术和新合成的古生态数据的跨学科研究，以推断北极物种如何受到过去气候、植被和种群连通性变化的影响。它建立在研究人员之前的大量工作基础上，包括数百块来自永久冻土的先前14C年代的马骨，这些骨骼构成了全球独一无二的古代DNA档案。

Title: Land Bridges, Ice-Free Corridors, and Biome Shifts: Impacts on the Evolution and Extinction of Horses in Ice-Age BeringiaThis study asks: How important was connectivity among populations of large arctic mammal species for maintaining genetic diversity, influencing evolutionary change, and mitigating extinction risk? What types of barriers affected this connectivity, and how permeable were these barriers to gene flow? The PIs will study how caballine horses, that inhabited ice-age Beringia (the biogeographic connector between Asia and North America), were affected by changes involving three different biogeographic barriers/corridors (1. the Bering Strait/Bering Land Bridge, which controlled dispersal and gene flow between Eurasia and Alaska; 2. the Ice-Free Corridor, which controlled gene flow between the Yukon and the Lower 48 States; and 3. biome shifts that periodically disrupted the spatial continuity of the Mammoth-Steppe, the unique ecosystem that stretched from France to the Yukon during the ice ages) during the last 30,000 years of the ice age. This study will evaluate the effects that each of these putative barriers to gene flow had on the abundance, distribution, and evolutionary trajectories of ice-age horses in the Arctic using new paleogenomic and paleoenvironmental data. The results will provide new insights into the roles played by environmental change and population fragmentation in determining extinction risk, and help predict how ongoing environmental changes will affect arctic ecosystems. This project will lead to advances in the rapidly developing field of paleogenetics and further the brand-new discipline of paleogenomic ecology. The Broader Impacts plan focuses on: a) research and professional development opportunities for graduate students, b) new training opportunities for undergraduate students who aspire to become STEM high school teachers, c) outreach to Native communities in rural Alaska, and d) outreach to K-12 students in Fairbanks, AK. At the end of each summer, the pre-service teachers, graduate students, and PIs will produce an inquiry activity module for grades 9-12 to be shared with local schools. Finally, the PIs will engage in both professional and public discourse, and use the results in media productions.This is an interdisciplinary study combining cutting-edge paleogenomic techniques with newly synthesized paleoecological data to infer how arctic species were affected by past changes in climate, vegetation, and population connectivity. It builds on extensive previous work by the investigators, including hundreds of previously 14C-dated horse bones from permafrost that comprise a globally unique archive of ancient DNA.