Did Hunting or Climate Change Cause a Late Holocene Bottleneck in California Tule Elk? An Integrated Test using Ancient DNA and Stable Isotopes

最近的研究表明，在过去的3000年里，史前猎人可能导致北美西部许多地区的羚羊、鹿和麋鹿等猎物物种的数量下降。这项工作表明，这些下降的影响是深远的，范围从人类行为和生物学的变化，涉及暴力增加和人类健康下降，到现代野生动物管理。然而，标准的猎物数量下降的考古指标--例如大型猎物骨骼丰度的下降--是不完善的，无法区分大规模猎物数量下降与猎物远离人类住区的局部运动。此外，很难评估气候变化对猎物减少的影响，因为很难将考古骨骼丰度数据的时间序列与各种气候变化记录的时间序列相一致。人们需要一种更强有力的方法--一种更直接地了解包括气候变化在内的具体原因的方法。本研究开发并测试了这种方法，使用古代DNA（aDNA）和来自麋鹿骨骼的稳定同位素（马鹿），加州景观中最大和最具经济吸引力的陆生动物。该项目建立在先前对图勒麋鹿的试点研究的基础上，并使用来自古代线粒体DNA（mtDNA）的遗传变异模式和稳定同位素，来验证史前猎人导致这种动物数量下降的假设。遗传变异的趋势被用来重建图勒麋鹿人口的历史，因为人口下降留下了遗传变异的签名。从动物骨骼中提取的碳、氧和氮的稳定同位素记录了动物饲料的各个方面，可用于重建陆地气候变化。这项工作将分析来自加州中部两个考古遗址的113头图勒麋鹿个体骨骼的古代线粒体DNA和稳定同位素，那里有大量的麋鹿遗骸。所有产生aDNA序列和稳定同位素值的标本将进行放射性碳年代测定，以提供年代控制。该分析不仅代表了一种新颖的aDNA和稳定同位素方法的整合，以重建和评估该地区原住民的关键生存资源的史前人口趋势，而且可以成为探索人类和气候影响对其他考古环境中动物的作用的模型。该项目对重建古代动物人口规模趋势的方法学具有影响，人类史前史和加州历史生态学的关键问题，以及图勒麋鹿保护和管理的当前问题。该项目还将继续培养一名在试点研究中从事aDNA工作的博士后学生，并支持和培训一名稳定同位素分析研究生研究助理。最后，该项目将为一个新的分子动物考古学研究项目提供关键的刺激，该项目致力于了解北美其他动物物种的种群历史。拟议的项目和发展中的研究计划整合了犹他州大学人类学系四名教师的研究专长，并将提高本科教学和研究生水平的培训和研究机会。

Recent research has suggested that prehistoric hunters may have caused declines in the populations of prey species such antelope, deer, and elk over the last 3000 in many areas of western North America. This work has shown that the implications of these declines are far-reaching and range from changes in human behavior and biology involving increasing violence and declining human health, to modern wildlife management. Standard archaeological indicators of prey population declines - such as declining abundances of the bones of large game - are, however, imperfect and cannot distinguish between broad-scale prey population declines versus local movements of prey away from human settlements. In addition, it is hard to evaluate the effect of climate change on prey declines, because of the difficulty in aligning time series of archaeological bone abundance data with those from various records of climate change. One needs a more robust methodology - one that informs more directly about specific causes including climate change. This research develop and test such a methodology using both ancient DNA (aDNA) and stable isotopes derived from the bones of elk (Cervus elaphus), the largest and most economically attractive terrestrial animal on the California landscape.The project builds on a previous pilot study with tule elk and uses patterns of genetic variation derived from ancient mitochondrial DNA (mtDNA), and stable isotopes, to test the hypothesis that prehistoric hunters caused a population decline in this animal. Trends in genetic variation are used to reconstruct the tule elk population history since population declines leave a signature in genetic variation. The stable isotopes of carbon, oxygen, and nitrogen recovered from faunal bone register aspects of an animal's forage and can be used to reconstruct terrestrial climate change. The work will analyze ancient mtDNA and stable isotopes from the bones of 113 tule elk individuals from two archaeological sites in central California where elk remains are abundant. All specimens that produce aDNA sequences and stable isotope values will be radiocarbon dated to provide chronological control. The analysis not only represents a novel integration of aDNA and stable isotope methodologies to reconstruct and evaluate the prehistoric population trends of a key subsistence resource to the aboriginal people of the region, but can be a model for exploring the role of human and climatic influences on animals in other archaeological settings.The project has implications for the methodology of reconstructing trends in the populations sizes of ancient animals, key issues in the human prehistory and historical ecology of California, as well as current issues in tule elk conservation and management. The project will also continue the career development of a post-doctoral student who has conducted the aDNA work in the pilot study and support and train a graduate student research assistant in stable isotope analysis. Finally, the project will provide a key stimulus to a new Molecular Zooarchaeology research program devoted to understanding the population histories of other animal species in North America. The proposed project and developing research program integrates the research expertise of four faculty members of the Department of Anthropology, University of Utah, and will enhance both undergraduate teaching and graduate level training and research opportunities.