Doctoral Dissertation Improvement Award: Aridification and Environmental Change

生物多样性的内在价值和经济价值使物种灭绝成为一个重大的社会问题。为了保护现有的物种多样性，必须了解生物多样性丧失的过去和现在的驱动因素。考古学和古生态学为人类、其他生物和气候之间的相互作用提供了相关的、长期的视角。该项目将回答几个长期存在的问题，即干燥的气候和人类和相关引进物种对马达加斯加的早期殖民化可能导致岛上大型动物的过去灭绝。例如，人类在多大程度上猎杀了现已灭绝的动物？引入的动物是否与现已灭绝的土著动物竞争？引入的动物是否比土著动物更耐旱？认识到区域变化的来源之间的反馈是一个挑战，但马达加斯加的数据集的案例研究是广泛适用于生物体之间的相互作用，在面对干旱化的研究。鉴于这项研究与当前环境问题的相关性以及马达加斯加西南部干旱地区正在制定与干旱有关的政策，社区和地方政府的外联是项目的优先事项。这项跨学科的工作涉及马达加斯加大学的学生和教师，通过本研究的实地部分培训的学生将获得适用于数据收集和自然资源管理的技能。本研究调查了人类和引入物种在新环境中的到来可能导致过去和正在发生的生物多样性丧失的许多方式中的一些。该项目的实地部分侧重于马达加斯加西南海岸。这一地区是研究人类活动引起的环境变化的理想之地，因为人类和人类引入的动物（如山羊、猪、牛、狗、猫和老鼠）在几千年前就来到了岛上，而且沿着这条海岸线有大量灭绝的特有动物（如侏儒河马、巨龟、象鸟和巨狐猴）的骨头。调查和挖掘一系列有过去人类存在痕迹的沿海池塘有助于恢复过去人类活动和生物多样性丧失的物质记录。从野外工作和博物馆收藏中回收的骨骼的放射性碳测年提供了时间控制，这对于推断人类，其他生物体和环境变化之间的过去相互作用是必要的。对放射性碳年代测定的骨蛋白进行一系列化学分析，可用于追踪生物体饮食和环境的各个方面。这些分析，再加上一项单独资助的努力，通过对古代湖泊沉积物的化学分析来重建该地区过去的气候，该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准。

The intrinsic and economic values of biodiversity make species extinction a significant societal concern. To conserve the existing variety of species, it is important to understand past and present drivers of biodiversity loss. Archaeology and paleoecology provide relevant, long term perspectives on interactions among humans, other organisms, and climate that contribute to extinctions. This project will answer several longstanding questions regarding how a drying climate and the early colonization of Madagascar by humans and associated introduced species may have contributed to past extinctions of large animals on the island. For example, to what extent did humans hunt the now extinct animals? Did introduced animals compete with now-extinct natives, and were introduced animals drought-tolerant relative to natives? Recognizing feedbacks among sources of regional change is a challenge, but this case study of datasets from Madagascar is broadly applicable to the study of past interactions among organisms in the face of aridification. Given the relevance of this research to present environmental concerns and the ongoing development of drought-related policy in arid southwest Madagascar, community and local government outreach is a project priority. This interdisciplinary work involves students and faculty at Malagasy universities, and the students trained through the field component of this research will gain skills applicable to data gathering and natural resource management.This research investigates some of the many ways in which the arrival of humans and introduced species in a novel environment may have contributed to past and ongoing biodiversity loss. The field component of this project focuses on the coast of southwest Madagascar. This region is ideal for studies of environmental changes associated with human activity, because humans and human-introduced animals (e.g. goats, pigs, cattle, dogs, cats, and rats) arrived on the island several thousand years ago, and the bones of extinct endemic animals (e.g. pygmy hippos, giant tortoises, elephant birds, and giant lemurs) are abundant along this coastline. Survey and excavation of a series of coastal ponds with traces of past human presence serve to recover the material record of past human activity and biodiversity loss. Radiocarbon dating of bone recovered from fieldwork and museum collections provides the chronological control that is necessary to infer past interactions among humans, other organisms, and environmental change. A series of chemical analyses of radiocarbon-dated bone protein is used to trace aspects of organisms' diets and environments through time. These analyses, coupled with a separately-funded effort to reconstruct the past climate of the region through the chemical analysis of ancient lake sediments, make it possible to examine potential synergies between past human activity and the changing climate that may have driven past extinctions on the island.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.