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

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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.