Collaborative Research: Human and non-human influences on species biodiversity in an island ecosystem

研究过去的大规模灭绝事件可以帮助我们理解现代世界全球生物多样性的下降。在这个多学科项目中，研究人员想要了解是什么引发了马达加斯加所有大型原生脊椎动物最近的灭绝，包括黑猩猩和大猩猩大小的狐猴、巨大的“象鸟”和有角的鳄鱼。在马达加斯加西南部的Tsimanampesotse国家公园（TNP），在以前未被探索过的洪水和干燥洞穴中发现了非同寻常的化石和石笋沉积物，这为研究人员解决这个问题提供了新的机会。一个由人类学家、地质学家和生态学家组成的国际团队将与洞穴潜水员合作，从被水淹没的洞穴和附近的干沉积物中检索和研究化石和石笋。通过从石笋中提取少量岩石样本并研究其化学成分，该团队将能够非常精确地重建过去5万年中栖息地和降雨的变化。小组成员还将记录小动物存在或不存在的变化，这可能是栖息地转变的极好指标。通过这项工作，他们将确定马达加斯加大型脊椎动物灾难性下降和灭绝的具体转折点，这将对如何避免该岛和其他地方未来的灭绝具有广泛的意义。该小组将通过绘制被水淹没的洞穴和化石沉积物的3D地图，以及多语言、多媒体教育展示，支持公众科学宣传。展览将重点关注保护，以及了解过去如何为未来提供信息。最后，该项目将支持三名研究生的博士论文，并为未来的国际合作研究建立机会。调查人员将利用人类学、生态学、洞穴科学和古气候学等最先进的技术，梳理环境变化和人类活动如何影响动植物群落。这项工作具有挑战性，特别是因为自然干旱化（通过减少降雨量）和人为干扰（通过放火、砍伐树木、养牛或其他引进的驯养动物以及种植作物）会对野生动植物的分布和丰富程度产生类似的破坏性影响。然而，石笋保存了当地降雨和植被变化的精确年代记录。因此，有可能知道什么时候降雨和植被共同变化，以及什么时候植被的变化独立于降雨，这意味着一些其他因素，如人类，是负责任的。动物的骨骼和牙齿可以保存有关存活和灭绝的物种的饮食、活动、运动和栖息地的可追溯证据。有时，化石表面的痕迹本身就保存了个体死亡的证据——例如，死于掠食性鸟类、食肉动物或人类。这个项目将梳理出环境变化和人类活动的相对重要性，并建立一个物种生存和灭绝的年表。岩石、骨骼和牙齿化学科学的进步，加上古生物学分析的老式工具（鉴定化石并记录它们之间的联系），使这一切成为可能。该奖项反映了美国国家科学基金会的法定使命，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。

Studying large-scale extinction events in the past can help us understand declines in global biodiversity in our modern world. In this multidisciplinary project, the investigators want to understand what triggered the recent extinction of all of Madagascar's large native vertebrates, including its chimpanzee- and gorilla-sized lemurs, enormous 'elephant birds,' and horned crocodiles. The discovery of extraordinary deposits of fossils and stalagmites in previously-unexplored flooded and dry caves at Tsimanampesotse National Park (TNP) in southwestern Madagascar has opened new opportunities for researchers to address this question. An international team of anthropologists, geologists and ecologists will work with cave divers to retrieve and study fossils and stalagmites from the flooded caves and nearby dry deposits. By taking small samples of rock from stalagmites and studying their chemistry, the team will be able to reconstruct with great precision changes in habitat and rainfall over the past 50,000 years. Team members will also document changes in the presence or absence of small animals that may be excellent indicators of habitat transformation. Through this work, they will identify specific turning points in the catastrophic decline and extinction of Madagascar's large vertebrates, which will have broad implications for how to avoid future extinctions on the island and elsewhere. The team will support public science outreach with creation of 3D maps of the flooded caves and fossil deposits, and multi-language, multi-media educational displays. The displays will focus on conservation, and how understanding the past can inform the future. Finally, this project will support the doctoral dissertations of three graduate students, and build future opportunities for international collaborative research. The investigators will utilize state-of-the-art techniques from anthropology, ecology, cave science and paleoclimatology to tease apart how environmental changes and human activities affect communities of plants and animals. This work is challenging, especially since natural aridification (through reduced rainfall) and human disturbance (through setting fires, cutting trees, raising cattle or other introduced domesticated animals, and planting crops) can have similar devastating effects on the distribution and abundance of wild plants and animals. However, stalagmites preserve precisely-datable records of changes in local rainfall and vegetation. Consequently, it is possible to know when rainfall and vegetation co-varied, and when vegetation changed independent of rainfall, implying that some other agent, such as humans, was responsible. Bones and teeth of animals can preserve datable evidence of the diets, activities, movements and habitats of species that have survived, and those that have not. Sometimes traces on the surfaces of fossils themselves preserve evidence of how individuals died - for example, by succumbing to a predatory bird, carnivore or human. This project will tease apart the relative importance of environmental change and human activities, and build a chronology of the survival and extinction of species. Advances in the science of the chemistry of rocks, bones, and teeth, coupled with the old-fashioned tools of paleontological analysis (identifying fossils and recording their associations) have made all of this possible.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.