OPP-PRF: Investigating the Effects of Late Holocene Climate Change on Polar Bears

北极熊进化到能在恶劣的北极环境中茁壮成长。因为它们依靠海冰来旅行和捕猎海豹，过去的气候变化改变了海冰，可能会影响种群的规模和分布。这个项目调查了从大约5000年前到现在的气候变化对白令海地区北极熊的影响。在阿拉斯加乌纳拉斯卡岛一处有4700年历史的考古遗址中发现了北极熊遗骸。这些遗骸位于最近发现北极熊的地方以南大约200英里处。通过研究这些遗骸，并将它们与现代标本进行比较，这项研究将促进人们对历史上气候变冷和当今气候变暖对北极熊的影响的理解。北极熊遗骸的存在对当地的乌南甘人也有影响。为了探索乌南加祖先与北极熊之间的关系，该项目将为学生提供培训和指导，并促进早期职业北极科学家的专业发展。这项研究的结果将通过会议报告和同行评议的文章与阿拉斯加荷兰港的社区分享。该项目测试了全新世晚期气候变化导致白令海北极熊人口、基因组和表观基因组变化的假设。PI采用多学科方法，结合从乌纳拉斯卡岛考古遗址出土的新冰川熊遗骸中获得的动物考古学、古基因组学和古表观遗传学数据。首先，将使用形态计量学和基因组DNA序列数据来确认遗骸来自北极熊，并确定组合中代表的个体数量。然后，将来自Unalaskan熊的基因组和表观基因组数据与来自阿拉斯加半岛的现代白令海北极熊和棕熊的数据进行比较，以确定1)北极熊和棕熊是否在新冰川期杂交，2)评估北极熊种群对新冰川期变冷和当今气候变暖的人口统计学和适应性反应。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。

Polar bears evolved to thrive in the harsh Arctic environment. Because they depend on sea ice to travel and to hunt seals, past climatic changes that altered sea ice likely affected population size and distribution. This project investigates the effects of climate change – from approximately 5000 years ago to the present – on polar bears in the Bering Sea region. Polar bear remains have been identified from a 4700-year-old archaeological site on Unalaska Island, Alaska. These remains are approximately 200 miles south of where polar bears have been found in the recent past. By studying these remains, and comparing them to modern-day specimens, this research will advance understanding of the effects of historic climate cooling and present-day climate warming on polar bears. The presence of polar bear remains also has implications for the Native Unangan people. To explore the relationship between Unangan ancestors and polar bears, this project will provide training and mentorship to students and enhance the professional development of an early career Arctic scientist. Results from this study will be shared with the community in Dutch Harbor, Alaska, and through conference presentations and peer-reviewed articles.This project tests the hypothesis that late Holocene climate change resulted in demographic, genomic, and epigenomic changes in Bering Sea polar bears. The PI uses a multidisciplinary approach, combining zooarchaeological, paleogenomic and paleoepigenetic data from Neoglacial bear remains excavated from an archaeological site on Unalaska Island. First, morphometric and genomic DNA sequence data will be used to confirm that the remains are from polar bears and to determine the number of individuals represented in the assemblage. Then, genomic and epigenomic data from the Unalaskan bears will be compared to data from modern-day Bering Sea polar bears and brown bears from the Alaska Peninsula to determine 1) if polar bears and brown bears interbred in the Neoglacial Period, and 2) to assess demographic and adaptive responses of polar bear populations to Neoglacial cooling and present-day climate warming.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.