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。为了保护现有物种的多样性，重要的是要了解过去和现在导致生物多样性丧失的驱动因素。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、长期的观点，这些因素导致了物种灭绝。该项目将回答几个长期存在的问题，即干燥的气候和人类及相关引入物种对马达加斯加的早期殖民可能是如何导致岛上大型动物过去灭绝的。例如，人类在多大程度上猎杀了这些现已灭绝的动物？引进的动物是否与现已灭绝的原住民竞争，以及引入的动物相对于原住民来说是耐旱的吗？识别区域变化来源之间的反馈是一项挑战，但马达加斯加数据集的这一案例研究广泛适用于研究面对干旱化的生物之间过去的相互作用。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与干旱有关的政策的持续发展，社区和地方政府的宣传是项目的优先事项。这项跨学科的工作涉及马达加斯加大学的学生和教职员工，通过这项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。这项研究调查了人类的到来和在新环境中引入的物种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。该项目的实地部分重点放在马达加斯加西南部的海岸。这一地区是研究与人类活动相关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)在几千年前到达该岛，而且这条海岸线上有大量已灭绝的特有动物(如侏儒河马、巨型乌龟、象鸟和巨型狐猴)的骨骼。调查和挖掘一系列带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。对从田野调查和博物馆收藏中发现的骨骼进行放射性碳测年，提供了推断过去人类、其他生物和环境变化之间相互作用所必需的时间控制。放射性碳骨蛋白的一系列化学分析被用来追踪生物体的饮食和环境的各个方面。这些分析，再加上一个单独资助的通过对古代湖泊沉积物进行化学分析来重建该地区过去气候的努力，使得研究过去的人类活动和可能导致岛屿过去物种灭绝的气候变化之间的潜在协同作用成为可能。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.