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.

这是加利福尼亚大学 - 洛斯·阿格尔斯大学（University of California-Los Angles）和圣克鲁斯（Santa Cruz），阿拉斯加 - 费尔班克斯大学（University of Alaska-Fairbanks）和史密森尼学会（Smithsonian Institution）的首席研究人员的合作提议。该奖项将由生物学和北极自然科学计划的人口生态学计划的资金得到支持。未来气候变化对北极物种的影响是极大的不确定性和关注的根源，自上次冰川周期以来，北极的气候变化很大。 因此，对先前扰动的生物反应的研究可能会提供重要的证据，表明北极物种的遗传多样性，饮食和地理范围如何因未来的全球气候变化而改变。利用DNA分析，主要研究人员将根据贫瘠的北美驯鹿和灭绝的北极马研究基于贝林亚三个地区的样本的灭绝态度的历史。从永久冻土中回收的骨骼是古代DNA的绝佳来源，可以日期为14c。最近的两项遗传学研究分析了北极永久冻土中的棕熊骨骼中的DNA序列，并发现了过去40，000年中三个不同的遗传时期的证据，每个遗传时期都由人口周转事件。这些先前未认可的时期是由超过35,000（ka）bp的标本的DNA序列定义的，从21至10 ka bp的标本和现代种群的序列定义。 古气候研究提供了证据表明，这些时期之间的人口周转可以通过与中威斯康星州内部，最后一次冰川最大和全新世有关的气候变化来解释。然而，古环境数据稀疏且尚无定论，这些遗传模式尚未在其他物种中得到验证。作为食草动物，驯鹿和马匹与棕熊的营养水平不同，两种物种都专门摄入不同类型的植被（分别分别为苔原和草牛皮）。 首席研究人员预测，生态系统范围内的气候变化对大型草食动物及其捕食者不利，这将导致这两个地区的两个物种的人口离职同步周期。这些变化应与先前在棕熊和灰狼中观察到的变化相匹配。类似的区域或局部生态系统变化将表现为在一个地区的一部分中的同步周期。相反，这两种物种的遗传变化模式的不同模式意味着苔原/森林优势或新物种特异性竞争者和/或捕食者的存在变化。无论哪种情况，该研究都将提供重要的证据，证明气候变化对北极哺乳动物的遗传多样性的潜在作用。 主要研究人员将通过研究所有三个地点的三个独立的环境替代物，确定环境变化的特定特定代理，并重建过去的北极环境。首先，他们将开发稳定的同位素谱，以用于DNA研究中分析的遗骸。这些特征将成为区域气候变化的代理，并允许推断动物饮食的改变。其次，他们将使用嵌入食草动物牙齿中的植物材料来重建两种草食动物利用的局部植物群的变化。第三，他们将利用现有的花粉记录和其他古环境数据在观察到的遗传周转期间重建区域植被和一般气候。重要的是，他们将在整个Beringia的两种草食动物物种中14C日期300骨，这将使他们的结果置于时间环境中，以允许与现有气候数据集成。 寄宿生的影响：随着新技术和问题的出现，所有数据都将放置在公共领域，以进行未来的研究。此外，这项研究将培训一组学生进行尖端，跨学科研究，其中结合了遗传学，花粉分析，高分辨率放射性碳年代测定和稳定的同位素生态学。