EAR-PF: Multi-Scale Calibrations of Fecal Biomarkers: New Tools to Evaluate How Herbivores Shaped Past Ecosystem Dynamics

Allison Karp博士获得美国国家科学基金会EAR博士后奖学金，在耶鲁大学和布朗大学开展研究和教育计划。大型食草哺乳动物正受到威胁，但目前尚不清楚这些正在变化的群落如何影响植被、火灾和营养循环。虽然这些动态可以通过检查过去食草动物如何影响生态系统功能来测试，但可用于重建食草动物群落变化以及其他环境变量的工具是有限的。这项研究将从根本上改进地球化学工具，通过使用来自南非国家公园的各种野生食草动物样本调查食草动物生物标志物，来分析过去的食草动物动态。卡普博士还将为耶鲁大学“科学之路”项目的两个部分编写教育和推广材料，该项目为纽黑文的初高中学生以及更广大的公众提供免费的科学项目。这项工作将通过一项全面的研究来改进沉积物岩心中过去草食动物动态的重建，以限制是否可以从野生草食动物群落产生的粪便生物标志物中获得草食动物密度和群落特征的信息。为此，Karp博士将在克鲁格国家公园（南非）开展一个综合多尺度校准项目。非洲稀树草原是为数不多的拥有多种大型食草动物群落的系统之一，对非洲稀树草原的关注优化了这些校准，以解决与第四纪已灭绝的食草动物群落变化相关的问题。本研究将：1)测试粪便中生物标志物浓度和分布的变化是否与草食动物功能群的变化有关；2)在长达10年的草食动物排斥实验中检测土壤中粪便生物标志物浓度和微生物降解；3)将沉积粪便生物标志物特征与历史草食动物群落丰度和多样性的变化进行校准。这个项目结合了现代生态学家和古生态学家的观点，产生了基于现代环境的古环境见解。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。

Dr. Allison Karp has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at Yale University and Brown University. Large-bodied mammalian herbivores are under threat, but it is unclear how these currently shifting communities may affect vegetation, fire and nutrient cycles. While these dynamics can be tested by examining how herbivores impacted ecosystem functions in the past, the tools available to reconstruct herbivore community changes alongside other environmental variables are limited. This research will fundamentally improve geochemical tools to analyze past herbivore dynamics by investigating herbivore biomarkers using samples from a National Park in South Africa with diverse wild herbivores. Dr. Karp will also develop educational and outreach materials for two parts of Yale’s Pathways to Science, which provides free scientific programing to middle and high-schoolers in New Haven as well as the greater public. This work will improve reconstructions of past herbivore dynamics from sediment cores with a comprehensive study to constrain if information about herbivore densities and community characteristics can be derived from fecal biomarkers produced from wild herbivore communities. To this end, Dr. Karp will conduct an integrated multi-scale calibration project in Kruger National Park (South Africa). The focus on African savannas, one of the few systems with a community of diverse megaherbivores, optimizes these calibrations to address questions related to shifts in extinct Quaternary herbivore communities. This research will: 1) test whether variation in fecal biomarker concentrations and distributions in dung is related to variation in herbivore functional groups, 2) examine fecal biomarker concentrations and microbial degradation in soils from decade-long herbivore exclusion experiment plots, and 3) calibrate sedimentary fecal biomarker characteristics to variation in the abundance and diversity of historical herbivore communities through time. This project combines the perspectives of modern and paleo-ecologists to produce paleoenvironmental insights grounded in modern settings.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.