Collaborative Research: Analysis of a Forty Thousand Year Record of Genetic and Environmental Change in the Arctic

合作研究：对北极四万年遗传和环境变化记录的分析

• 批准号: 0352564
• 负责人: Paul Koch
• 金额: $ 11.14万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0352564&HistoricalAwards=false
• 关键词: Collaborative; Research; Analysis; Forty; Thousand

This is a collaborative proposal by Principal Investigators at the University of California-Los Angles and Santa Cruz, University of Alaska-Fairbanks, and the Smithsonian Institution. This award will be supported with funds from the Population Ecology Program in the Division of Biology and Arctic Natural Sciences Program. The effects of future climatic change on arctic species are a source of great uncertainty and concern and the Arctic has experienced large changes in climate since the last glacial cycle. Therefore, the study of biotic responses to the previous perturbations may provide important evidence of how the genetic diversity, diet, and geographic range of arctic species will be altered by future global climate change. Using DNA analysis, the Principal Investigators will examine the history of genetic diversity in the barren-ground caribou and an extinct arctic horse based on samples from three localities in Beringia. Bones recovered from the permafrost are an excellent source of ancient DNA and can be 14C dated. Two recent genetic studies analyzed DNA sequences from brown bear bones entombed in the arctic permafrost and found evidence of three distinct genetic epochs over the past 40,000 years, each marked by population turnover events. These previously unrecognized epochs are defined by DNA sequences from specimens older than 35 thousand (ka) BP, from specimens 21 to 10 ka BP, and by sequences from modern populations. Paleoclimate studies provide evidence that population turnover between these periods may be explained by changing climate relating to the mid-Wisconsin interstadial, the last glacial maximum, and the Holocene. However, paleoenvironmental data are sparse and inconclusive and these genetic patterns have not been verified in other species. As herbivores, caribou, and horses represent a different trophic level from brown bears and both species specialize on consuming different types of vegetation (tundra and grass-steppe, respectively). The Principal Investigators predict that ecosystem-wide climate change unfavorable to large herbivores and their predators would result in synchronous cycles of population turnover in both species across all three localities. These changes should match those previously observed in the brown bear and gray wolf. Similar regional or local ecosystem change would be manifest as synchronous cycles in a subset of localities. In contrast, differing patterns of genetic change in the two species would imply a change in the tundra/forest dominance or the presence of new species-specific competitors and/or predators. In either case, the study will provide important evidence of the potential role of climate change on genetic diversity in arctic mammals. The Principal Investigators will identify specific agents of environmental change and reconstruct past arctic environments through study of three independent classes of environmental surrogates in all three locations. First, they will develop stable isotope profiles for the remains analyzed in the DNA study. These profiles will serve as proxies for regional climate change and allow changing animal diets to be inferred. Second, they will use plant material imbedded in the teeth of herbivores to reconstruct the changes in local flora utilized by the two herbivores. Third, they will utilize existing pollen records and other paleoenvironmental data to reconstruct the regional vegetation and general climate during periods of observed genetic turnover. Importantly, they will 14C date 300 bones from the two herbivore species across Beringia which will place their results in a temporal context that will allow integration with existing climate data. Boarder Impact: All data will be placed in the public domain for future studies as new techniques and questions arise. Additionally, this research will train a group of students in cutting-edge, interdisciplinary research that incorporates genetics, pollen analysis, high-resolution radiocarbon dating, and stable isotope ecology.

这是加州大学洛杉矶分校和圣克鲁斯分校、阿拉斯加大学费尔班克斯分校和史密森尼学会的首席研究员的合作提案。该奖项将得到生物学和北极自然科学项目部人口生态学项目的资金支持。未来气候变化对北极物种的影响引起了极大的不确定性和担忧，自上一次冰川周期以来，北极经历了巨大的气候变化。 因此，对生物对先前扰动的反应的研究可能为未来全球气候变化将如何改变北极物种的遗传多样性、饮食和地理范围提供重要证据。首席研究员将利用 DNA 分析，根据白令陆桥三个地区的样本，研究贫瘠之地驯鹿和灭绝的北极马的遗传多样性历史。从永久冻土中回收的骨头是古代 DNA 的极好来源，可以进行 14C 测年。最近的两项遗传学研究分析了埋藏在北极永久冻土中的棕熊骨头的 DNA 序列，发现了过去 4 万年中三个不同遗传时期的证据，每个时期都以种群更替事件为标志。这些以前未被识别的时代是由距今 35000 (ka) BP 之前的样本、距今 21 至 10 ka BP 样本的 DNA 序列以及现代人群的序列定义的。 古气候研究提供的证据表明，这些时期之间的人口流动可能是通过威斯康星州中部间质期、末次盛冰期和全新世相关的气候变化来解释的。然而，古环境数据稀疏且不确定，这些遗传模式尚未在其他物种中得到验证。作为食草动物，驯鹿和马代表着与棕熊不同的营养水平，并且这两个物种都专门消耗不同类型的植被（分别是苔原和草草原）。 首席研究员预测，整个生态系统的气候变化对大型食草动物及其捕食者不利，将导致所有三个地区的两个物种的种群更替周期同步。这些变化应该与之前在棕熊和灰狼身上观察到的变化相符。类似的区域或当地生态系统变化将表现为部分地区的同步循环。相比之下，两个物种的不同基因变化模式将意味着苔原/森林优势的变化或新物种特定竞争者和/或捕食者的存在。无论哪种情况，这项研究都将为气候变化对北极哺乳动物遗传多样性的潜在作用提供重要证据。 首席研究员将通过研究所有三个地点的三类独立的环境替代物来确定环境变化的具体因素并重建过去的北极环境。首先，他们将为 DNA 研究中分析的遗骸开发稳定的同位素谱。这些概况将作为区域气候变化的代理，并可以推断动物饮食的变化。其次，他们将利用嵌入食草动物牙齿中的植物材料来重建两种食草动物利用的当地菌群的变化。第三，他们将利用现有的花粉记录和其他古环境数据来重建观察到的基因更新期间的区域植被和总体气候。重要的是，他们将对白令陆桥两种食草动物的 300 块骨头进行 14C 年代测定，这将把他们的结果放在一个时间背景下，以便与现有的气候数据整合。 边境影响：随着新技术和问题的出现，所有数据都将放在公共领域，以供未来研究。此外，这项研究还将培训一批学生进行前沿的跨学科研究，其中包括遗传学、花粉分析、高分辨率放射性碳测年和稳定同位素生态学。