Novel geochemical methods for assessing trophic ecology in modern and ancient ecosystems

营养（消费者-猎物）动态是生态系统的基本组成部分。这些相互作用驱动着全球生态系统的功能和地球化学循环，并对过去和现在气候变化和人类活动的影响很敏感。饮食和营养相互作用的地球化学（同位素）代理是追踪这些动态的关键工具，而无需直接观察，是必不可少的一系列领域，从保护到古科学。在简单的营养系统中，传统的稳定同位素如碳（d13 C）和氮（d15 N）通常足以追踪猎物来源。然而，在更复杂的系统中，如各种食肉动物或涉及人类的环境，营养关系仍然部分或完全未解决的同位素研究。非洲的陆地生态系统非常复杂，拥有极其多样化的哺乳动物群落。这些生态系统塑造了我们物种的进化，但现在由于人类压力的增加而面临崩溃的风险。然而，我们的营养生态学在这些复杂的生态系统中使用目前的同位素代理产生模糊的结果，限制了我们的理解，这些生态系统如何随着时间的推移和人类的影响开始改变。 我的5年研究计划是：（1）使用最近开发的非洲生态系统中有机（d15 NAA）和无机（d26 Mg和d44 Ca）生物组织的营养替代物来调查哺乳动物的营养位置和饮食来源的变化，（2）将这些方法应用于过去人类饮食变化的调查，以了解史前人类活动的影响。该项目将为理解复杂生态系统中的营养联系奠定基础（例如，包括人类影响在内的多层营养系统），说明了人类压力从古代到现代的变化，并创建了一个可用于全球复杂陆地生态系统的分析框架。 该项目解决了（古）生态学研究的基本限制，使用新的地球化学方法来理解系统中的营养链，这些链很难用传统方法解决。本项目还将探讨史前时期人类饮食和人为影响的基本问题。这项工作将利用PI在东非超过10年的研究经验和联系，并将为学生提供机会，对这些项目进行博物馆和实验室研究。在项目的最后一年，我们还将在肯尼亚国家博物馆举办一次关于我们工作的研讨会，分享我们的研究成果，并为年轻的国际学者创造交流机会。该项目将促进国际合作，包括来自东非的学者，作为促进全球学者之间公平的持续努力。

Trophic (consumer-prey) dynamics are the essential building blocks of ecosystems. These interactions drive ecosystem functionality and biogeochemical cycles globally, and are sensitive to the impacts of climate change and human activity in the past and present. Geochemical (isotopic) proxies for diet and trophic interactions are critical tools for tracing these dynamics without direct observation and are essential for a range of fields from conservation to paleosciences. In simple trophic systems, traditional stable isotopes such as carbon (d13C) and nitrogen (d15N) are often sufficient to trace prey sources. However, in more complex systems, such as environments with diverse carnivores or those involving humans, trophic relationships remain partially or completely unresolved in isotopic studies. African terrestrial ecosystems are complex, hosting extraordinarily diverse mammalian communities. These ecosystems shaped the evolution of our species, yet now face risk of collapse as a result of increasing anthropogenic pressures. Yet, our understanding of trophic ecology in these complex ecosystems using current isotopic proxies yields ambiguous results, limiting our understanding of how these ecosystems have changed over time and when human impacts began. My 5-year research plan is to (1) to investigate changes in trophic position and diet source in mammals using recently developed trophic proxies of organic (d15NAA) and inorganic (d26Mg and d44Ca) biological tissues in African ecosystems, and (2) apply these approaches to investigations of human dietary change in the past in order to understand anthropogenic impact in prehistory. This project will lay the groundwork for understanding trophic connections in complex ecosystems (e.g., multi-tier trophic systems that include human impacts), illustrate shifting anthropogenic pressures from ancient to modern times, and create an analytical framework that can be used in complex terrestrial ecosystems globally. This project addresses a fundamental limitation of (paleo)ecological studies using new geochemical methods for understanding trophic links in systems where these links have been difficult to resolve with traditional methods. This project will also address fundamental questions of human diet and anthropogenic impacts in prehistory. This work will capitalize on the PI's >10 years of research experience and connections in eastern Africa, and will provide opportunities for students to conduct museum and lab-based research on these projects. We will also host a symposium on our work at the National Museums of Kenya in the project's final year to share our findings and create networking opportunities for young international scholars. This project will foster international collaborations, including academics from eastern Africa, as an ongoing effort to promote equity among the global community of scholars.