CAREER: Developing novel biomarker proxies to constrain Neogene changes in African woody cover and paleoecological contexts of hominin evolution

职业：开发新型生物标志物代理来限制非洲木质覆盖和古人类进化的古生态环境的新近纪变化

基本信息

批准号：
1945446
负责人：
Kevin Uno
金额：
$ 69.95万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2025-06-30
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1945446&HistoricalAwards=false
关键词：
CAREER Developing novel biomarker proxies

项目摘要

Today humans rely on grasses (e.g., corn, wheat, and rice) as a primary food source and for feeding livestock. This dependence on grasses has deep roots. Humans and their ancestors evolved in concert with grassland ecosystems in Africa over the past 7 million years. Despite the well-documented association between human evolution and grasslands, little is known about the origin of grasses in Africa, especially before 10 million years ago. When and how did grasses rise to ecological dominance? Lack of knowledge on this subject is largely due to the sparse plant fossil record. To understand how grasslands may have shaped the evolutionary trajectory of our species and other mammals, new, widely applicable approaches are needed to reconstruct ancient ecosystems. This project is developing new methods for reconstructing vegetation in past ecosystems using molecular plant fossils preserved in ancient sediments. Combining these approaches with existing isotopic methods, the researcher is reconstructing the rise of grasslands in East Africa over the past ~25 million years and exploring the relationships between climate, ecosystem, and evolutionary change. The results could produce new insights on the interconnectedness of climate, ecosystems and human evolution over geological timescales. A parallel objective throughout the project is to support students in their pursuit of STEM careers with an emphasis on increasing participation of underrepresented groups in the Earth sciences. The project includes intensive three-week field and lab courses for graduate students and postdocs from the US and African nations, lab-based research opportunities for undergraduate and New York City high school students, and support for a graduate student to conduct PhD research. African terrestrial ecosystems underwent revolutionary change in the Neogene. Sparse paleobotanical evidence suggests that denser forested ecosystems gave way to more open forests, woodlands, and perhaps nascent grasslands near the end of the early Miocene to the middle Miocene. This same period (~19 to 13 Ma) was marked by major changes in the primate and large mammal communities, yet the paleoecological context remains poorly known. By the late Miocene (10 Ma), carbon isotopic evidence shows that C4 grasslands began to spread. Despite the firm record of C4 grassland expansion beginning at 10 Ma, the role of ecological change in mammalian and human evolution through most of the Neogene has been insufficiently addressed. The Principal Investigator is developing organic geochemical approaches for reconstructing terrestrial ecosystem structure using modern ecosystems. This includes methods to estimate the fraction of woody cover from n-alkane molecular distributions and to measure grass abundance using PTMEs. Modern ecosystem research will also yield carbon and hydrogen isotope enrichment factors between biomarkers, bulk plant tissue, and soils. The researcher is applying these methods to terrestrial and marine sedimentary records from the Neogene Period in Africa to determine when and how grasslands became ecologically significant and how ecosystem change may have affected faunal and human evolution. The project will incorporate postdocs and graduate, undergraduate, and high school students into research, training, and field work. This includes developing a three-week paleoecology short course in Kenya for graduate students and postdocs from US institutions and African nations. The Principal Investigator is also providing research opportunities in his lab, built on a tiered mentoring program, for high school and undergraduate students from New York City. This program has high participation rates of students from underrepresented groups and serves as a pipeline for first-generation college students, many of whom ultimately major in STEM fields. One graduate student will be trained and supported by this project.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.

如今，人类依靠草（例如玉米，小麦和大米）作为主要食物来源和饲养牲畜。这种对草的依赖有根深蒂固的根源。在过去的700万年中，人类及其祖先与非洲的草原生态系统进行了演变。尽管人类进化与草原之间有据可查的关联，但对非洲的草的起源知之甚少，尤其是在一千万年前之前。草何时，如何升高生态主导地位？对该主题的知识不足很大程度上是由于植物化石记录稀疏。为了了解草原可能如何塑造我们物种和其他哺乳动物的进化轨迹，需要采用新的，广泛适用的方法来重建古代生态系统。该项目正在开发新的方法，用于使用保存在古代沉积物中的分子植物化石在过去的生态系统中重建植被。将这些方法与现有的同位素方法相结合，研究人员正在重建过去约2500万年的东非草原的兴起，并探索气候，生态系统和进化变化之间的关系。结果可能会产生关于气候，生态系统和人类在地质时间尺度上的相互联系的新见解。整个项目中的一个平行目标是支持学生追求STEM职业，重点是增加代表性不足的团体在地球科学中的参与。该项目包括针对研究生和非洲国家的研究生和博士后的密集的三周和实验室课程，基于实验室的本科和纽约市高中生的研究机会，并支持研究生进行博士学位研究。非洲陆地生态系统发生了革命性的变化。稀疏的古生物证据表明，茂密的森林生态系统让位于中新世早期末期附近的更开放的森林，林地，也许是新生的草原。同一时期（〜19至13 ma）的特征是灵长类动物和大型哺乳动物社区的重大变化，但古生态环境仍然鲜为人知。在中新世晚期（10 MA）的情况下，碳同位素证据表明C4草原开始扩散。尽管C4草原扩张的牢固记录从10 MA开始，但通过大多数新近纪在哺乳动物和人类进化中生态变化的作用尚未得到充分解决。主要研究者正在开发有机地球化学方法，用于使用现代生态系统重建陆地生态系统结构。这包括估计N-烷烃分布分布的木质覆盖物的分数，并使用PTME测量草的丰度。现代生态系统研究还将在生物标志物，散装植物组织和土壤之间产生碳和氢同位素富集因子。研究人员将这些方法应用于非洲新金元时期的陆生和海洋沉积记录，以确定草原何时以及如何在生态上具有生态意义以及生态系统变化如何影响动植物和人类的进化。该项目将将博士后和研究生，本科生和高中生纳入研究，培训和实地工作。这包括在肯尼亚为研究生和美国机构和非洲国家的博士后开发三周的古学简短课程。首席调查员还为来自纽约市的高中和本科生的分层指导计划建立了基于分层指导计划的研究机会。该计划的参与率很高，来自代表性不足的团体的学生，并为第一代大学生提供了渠道，其中许多人最终在STEM领域中专业。该项目将对一名研究生进行培训和支持。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评论标准来评估值得支持的。