Collaborative Research: The Lost Pastures of Alaska's Last Megafauna

合作研究：阿拉斯加最后巨型动物消失的牧场

• 批准号: 2131691
• 负责人: Daniel Mann
• 金额: $ 69.02万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2131691&HistoricalAwards=false
• 关键词: Collaborative; Research; Lost; Pastures; Alaska

Rapid climate changes are now impacting the animals and plants that live in the Arctic. Learning what happened when climate changed in the past can help predict what could happen over the next 50 years: Which species will become extinct, and why? Is there anything that can be done to protect Arctic species from the impacts of climate change? The goal of this project is to understand what caused the extinctions of giant, ice-age animals like woolly mammoth around the time that the last ice age ended. Some people think they were killed off by people; others say they died because of rapid changes in climate. No one knows for certain, but everyone argues about it. It is not even known when, exactly, these extinctions occurred: Was it 12,000 years ago, or 4000 years ago? This project aims at pin-pointing when the last mammoth, the last steppe bison, and the last tundra lion lived in Alaska. Once it is known for certain when they became extinct, it will be possible to eliminate some of the proposed explanations. For example, it may turn out that herds of mammoths still roamed across Alaska 4000 years ago. Because it is already known that the first people arrived in Alaska around 14,000 years ago, if this project shows that mammoths and people coexisted for 10,000 years, it makes it unlikely that people drove them to extinction. The research proposed here will obtain more precise dates on when the last ice-age mammals lived in Alaska using new methods based on the DNA that is preserved in frozen ground where these animals once lived. All animals (people included) continually shed DNA into the environment in their skin fragments, hair, feces, and urine. Some of these tissue fragments are buried and preserved in the ground. This is especially true in the Arctic where decay is slowed by cold temperatures. The plan is to extract tissue fragments (think: fur and dandruff) from the ground, and then use the DNA it contains to identify which animal species it came from. Next, the soil layer containing this DNA will be dated, and these new dates will be used to test ideas about what caused this species’ extinction. By better understanding the causes of extinctions in the past, the Arctic mammals that still survive can be better protected, species like polar bears, musk oxen, and caribou. A major goal of this study is to educate students and high school teachers about climate change, DNA, and ice-age ecology. A particular effort will be made to involve students who are Alaskan Natives. All data will be shared in archives that everyone has free access to, and new discoveries will be shared through scientific publications, newspaper articles, and public lectures. Arctic ecosystems now lie on the front lines of global change. There is an urgent need to better understand how rapid changes in temperature, sea-ice extent, and land use could impact large-bodied Arctic mammals like musk oxen, polar bears, and caribou. The geological record preserves many examples of what happened to animals and plants when climate changed rapidly during prehistory. Extinctions are of particular interest, because understanding what caused extinctions in the past can help us conserve the planet’s remaining megafauna, many of which are now endangered. A wave of extinctions occurred in the Arctic around the end of the last ice age, 14,000 to 10,000 years ago. This is when most scientists believe that giant ice-age mammals like woolly mammoth, steppe bison, tundra horses, and tundra lions disappeared from mainland Siberia and Alaska; however, no one is sure what caused these extinctions, and many explanations have been proposed. One reason for this debate is that a key piece of information is still missing, namely: When did these species actually go extinct? Unless it is known with precision when an extinction occurred, the various hypotheses about causation cannot be tested. Present understanding of when these extinctions occurred is based on a few hundred radiocarbon dates scattered across the northern continents, and there is a real possibility that the bones of the last woolly mammoth will never be discovered. But now there is a new and better way to detect the presence of now-extinct animals. All animals shed DNA into the environment in their skin fragments, hair, feces, and urine. Some of this DNA is buried and preserved in the ground, especially in the Arctic, where things decay slowly because it is cold. The aim of this project is to extract the ancient DNA of extinct mammals, use it to identify which species it belonged to, and then to date the soil layer where it came from. These new dates can then be used to test ideas about what caused this species’ extinction. In this study, emphasis will be placed on educating students and high school teachers about climate change, DNA, and ice-age ecology. A particular effort will be made to involve students who are Alaskan Natives. All our data will be shared in archives that everyone has free access to, and new discoveries will be shared through scientific publications, international conferences, newspaper articles, and public lectures.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.

快速的气候变化正在影响生活在北极的动植物。了解过去气候变化时发生了什么可以帮助预测未来50年可能发生的事情：哪些物种将灭绝，为什么？有什么可以做的来保护北极物种免受气候变化的影响吗？这个项目的目标是了解是什么原因导致了巨大的冰河时代动物，如长毛猛犸在最后一个冰河时代结束的时候灭绝。有些人认为他们是被人类杀死的;另一些人说他们是因为气候的快速变化而死亡的。没有人确切地知道，但每个人都在争论，甚至不知道这些事件发生在什么时候：是12,000年前，还是4000年前？这个项目的目的是确定最后一只猛犸、最后一只草原野牛和最后一只苔原狮生活在阿拉斯加的时间。一旦确定它们是何时灭绝的，就有可能消除一些提出的解释。例如，4000年前，猛犸象群可能仍然在阿拉斯加漫游。因为已经知道第一批人大约在14,000年前到达阿拉斯加，如果这个项目表明猛犸象和人类共存了10,000年，那么人类不太可能将它们推向灭绝。这项研究将利用保存在这些动物曾经生活过的冻土中的DNA，使用新方法获得最后一批冰河时代哺乳动物生活在阿拉斯加的更精确的日期。所有的动物（包括人类）都不断地将DNA以皮肤碎片、毛发、粪便和尿液的形式释放到环境中。其中一些组织碎片被埋在地下并保存下来。在北极地区尤其如此，那里的低温减缓了腐烂。该计划是从地面提取组织碎片（想想：毛皮和头皮屑），然后使用它包含的DNA来识别它来自哪个动物物种。接下来，含有这种DNA的土壤层将被确定年代，这些新的年代将被用来测试是什么导致了这个物种的灭绝。通过更好地了解过去灭绝的原因，仍然存活的北极哺乳动物可以得到更好的保护，如北极熊，麝牛和驯鹿。这项研究的一个主要目标是教育学生和高中教师关于气候变化，DNA和冰河时代生态学。一个特别的努力将涉及学生谁是阿拉斯加原住民。所有数据将在档案中共享，每个人都可以免费访问，新发现将通过科学出版物，报纸文章和公开讲座共享。北极生态系统现在处于全球变化的前沿。迫切需要更好地了解温度、海冰范围和土地利用的快速变化如何影响大型北极哺乳动物，如麝牛、北极熊和驯鹿。地质记录保存了史前时期气候迅速变化时动植物发生变化的许多例子。灭绝特别令人感兴趣，因为了解过去是什么导致了灭绝可以帮助我们保护地球上剩余的巨型动物，其中许多现在濒临灭绝。大约在14,000到10,000年前的最后一个冰河时代结束时，北极发生了一次大规模的灭绝。这是大多数科学家认为，大型冰河时代的哺乳动物，如羊毛猛犸，草原野牛，苔原马和苔原狮子从西伯利亚大陆和阿拉斯加消失的时候;然而，没有人确定是什么导致了这些消失，并提出了许多解释。这场争论的一个原因是，一个关键的信息仍然缺失，即：这些物种实际上是什么时候灭绝的？除非精确地知道灭绝发生的时间，否则关于因果关系的各种假设都无法得到检验。目前对这些灭绝事件发生时间的了解是基于分布在北方大陆的几百个放射性碳年代测定，而且最后一头长毛猛犸的骨骼有真实的可能永远不会被发现。但现在有一种新的更好的方法来检测现已灭绝的动物的存在。所有的动物都会通过皮肤碎片、毛发、粪便和尿液将DNA释放到环境中。其中一些DNA被埋在地下并保存下来，特别是在北极，那里的东西腐烂得很慢，因为它很冷。该项目的目的是提取已灭绝哺乳动物的古代DNA，用它来识别它属于哪个物种，然后确定它来自哪里的土壤层。这些新的日期可以用来测试是什么导致了这个物种的灭绝。在这项研究中，重点将放在教育学生和高中教师有关气候变化，DNA和冰河时代的生态。一个特别的努力将涉及学生谁是阿拉斯加原住民。我们所有的数据将在档案中共享，每个人都可以免费访问，新发现将通过科学出版物，国际会议，报纸文章和公开讲座分享。这个奖项反映了NSF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。