TROPICAL ECOSYSTEM RESPONSE TO LATE-QUATERNARY ENVIRONMENTAL CHANGE: INSIGHT FROM REMARKABLE ASPHALT-PRESERVED BIOTAS

在大约12000年前的上一个冰河时代结束时，地球上的大多数大型动物灭绝了，许多生态系统发生了巨大的变化。科学家们仍然不知道为什么会发生这些变化，因为化石记录不完整，只保存了及时的简短快照。一个例外是“焦油坑”，这是一个古生物遗址，在那里沥青(一种原油)数千年来渗入地表，保存着包括骨骼、木材和昆虫在内的整个生态系统的化石遗迹。在这个项目中，来自洛杉矶和秘鲁的科学家和大学生将共同挖掘和研究秘鲁焦油坑中的化石，重建生物多样性的冰河时代生态系统，并调查它是如何变成今天的贫瘠沙漠的。这次生态系统崩溃发生在气候变化和人类影响类似于现在发生的时候。人们希望研究这些过去的变化可以帮助防止未来的物种灭绝。该项目将让北美和南美的学生和科学家从秘鲁北部沿海的沥青地区(俗称“焦油坑”)中恢复、识别和描述化石材料。经过精选的动植物，包括植物、小型脊椎动物和无脊椎动物遗骸，将在这个研究较少的地区形成一个全面的、具有科学价值的晚第四纪化石收藏，并将进行分析，以调查人类、气候和生物群落之间的相互作用。这项研究将集中于三个主要问题：(1)在更新世大型哺乳动物群落消失之前，新热带西部沿海晚第四纪生态系统结构是什么？(2)该生态系统如何、何时以及对什么气候和人类活动经历了剧烈的生态状态变化而达到目前的沙化状态？以及，(3)这些过程如何与南美其他地区的环境变化和人为影响相结合，导致大陆和全球物种灭绝事件？该奖项反映了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。

At the end of the last Ice Age, about 12,000 years ago, most of the big animals on Earth went extinct and many ecosystems changed drastically. Scientists still don’t know why these changes happened because the fossil record is incomplete, preserving just brief snapshots in time. An exception are “tar pits,” paleontological sites where asphalt (a type of crude oil) seeped to the surface over thousands of years, preserving fossil remains of whole ecosystems including bones, wood, and insects. In this project, scientists and college students from Los Angeles and Peru will work together to excavate and study fossils from a Peruvian tar pit, reconstructing the biodiverse Ice Age ecosystem and investigating how it changed into the barren desert it is today. This ecosystem collapse occurred during a time of climate changes and human impacts similar to those happening now. It is hoped that studying these past changes can help prevent future extinctions. This project will engage North- and South American students and scientists in recovering, identifying, and describing fossil material from a north-coastal Peruvian asphaltic locality (colloquially, “tar pit”). The curated flora and fauna, comprising plant, small vertebrate, and invertebrate remains, will form a comprehensive and scientifically valuable late-Quaternary fossil collection in this poorly-studied region, and will be analyzed to investigate interactions between humans, climate, and biotic communities. This research will focus on three main questions: (1) What was the late-Quaternary ecosystem structure in the coastal western Neotropics, before the disappearance of the Pleistocene large mammal communities?; (2) How, when, and in response to what climatic and anthropogenic processes did this ecosystem undergo the dramatic ecological state change to its current desertified condition?; and, (3) How did these processes integrate with environmental changes and anthropogenic impacts in other South American regions, leading to a continental – and global – extinction event?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.