IRFP: Assessing the Role of Ecosystem Structure in Extinction Patterns During the Cretaceous-Paleocene Mass Extinction

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该项目的奖项提供了联合研究的机会，并提供了使用国外独特或互补的设施、专业知识和实验条件的机会。这一奖项将支持科里·M·雷德曼博士与克雷格·斯科特博士在加拿大阿尔伯塔省皇家泰雷尔古生物博物馆合作的为期24个月的研究奖学金。威胁现代生态系统的问题的严重程度类似于与大规模灭绝相关的地质时间间隔；因此，化石记录在了解生态系统对全球规模破坏的反应方面发挥了关键作用。然而，大多数古生态大规模灭绝的研究都集中在测量不同分类群之间的灭绝程度或试图确定造成物种灭绝的主要非生物原因(S)。生态系统结构在灭绝事件的传播或抵抗中的作用在很大程度上还没有得到研究。白垩纪-古近纪(K-PG)大灭绝是地球S历史上最臭名昭著的大灭绝之一，原因是恐龙的灭绝。尽管发表了大量的论文，但在K-PG事件之前陆地生态系统的稳定性或健康以及K-PG事件引起的生态系统变化方面仍存在相当大的争议。这项研究的目的是利用脊椎动物和花粉的整体组合、等级丰度曲线(RAC)来定量描述K-PG灭绝事件前后陆地生态系统结构的变化。RAC是一种生态技术，用于直观和定量地描述生态系统中的类群如何划分资源并将这些资源转化为丰富的资源。跨越K-PG边界的丰度结构的任何变化都将表明正在影响生态系统的过程中的变化(S)。利用现代生物和化石生物进行的生态学研究表明，物种丰度分布随着扰动的频率和大小而变化。经历过频繁扰动的生态系统通常由少数具有广泛栖息地范围或食物偏好的物种(即多面手)主导。相比之下，没有经历过频繁扰动的生态系统通常会在不同物种之间更平均地分配资源，每个物种都有非常窄的栖息地范围或食物偏好(即专家)。进行这项研究的基本原理是，通过使用占据不同营养水平的有机体(即脊椎动物=初级和次级消费者；花粉=初级生产者)直接分析灭绝前和灭绝后的生态系统，确定最新的白垩纪陆地生态系统是否在K-PG界线之前已经处于生态压力之下。

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship by Dr. Cory M. Redman to work with Dr. Craig Scott at the Royal Tyrrell Museum of Palaeontology in Alberta, Canada. The magnitude of the problems threatening modern ecosystems resembles those intervals of geological time associated with mass extinctions; for this reason the fossil record provides a critical role in understanding the responses of ecosystems to global-scale disruptions. However, most paleoecological mass extinction studies have focused on measuring the magnitude of extinction among various taxonomic groups or trying to identify the primary abiotic cause(s) of the extinction. The role of ecosystem structure in the propagation of or resistance to an extinction event has largely gone unstudied. The Cretaceous-Paleogene (K-Pg) mass extinction is one of the most infamous mass extinctions in Earth?s history, due to the demise of the dinosaurs. Despite the profusion of publications, considerable controversy remains on the stability or health of terrestrial ecosystems prior to the K-Pg event and the changes in ecosystem caused by the extinction. The objective of the research proposed here is to quantitatively characterize changes in terrestrial ecosystems' structure before and after the K-Pg extinction event, using whole assemblage, rank abundance curves (RACs) of vertebrates and pollen. RACs are an ecological technique used to visually and quantitatively describe how taxa in an ecosystem partition resources and convert these resources into abundances. Any change in abundance structure across the K-Pg boundary would indicate change(s) in the processes that are influencing the ecosystems. Ecological studies utilizing modern and fossil organisms have shown that species abundance distributions change as a result of the frequency and magnitude of perturbations. Ecosystems that have experienced frequent perturbations are typically dominated by a few species that have a wide habitat range or food preference (i.e., generalists). In contrast, ecosystems that have not experienced frequent perturbations typically have resources apportioned more evenly across a diverse array of species, each one having a very narrow habitat range or food preference (i.e., specialists). The rationale for conducting this study is to determine if latest Cretaceous terrestrial ecosystems were already under ecological stress prior to the K-Pg boundary by directly analyzing pre- and post- extinction ecosystems using organisms that occupy different trophic levels (i.e., vertebrates = primary & secondary consumers; pollen= primary producers).