Collaborative Research: Elements of an extinction: Exploring the delayed Caribbean extinction with stable isotopes and trace elements

合作研究：灭绝的要素：用稳定同位素和微量元素探索加勒比海延迟灭绝

• 批准号: 1325683
• 负责人: Ethan Grossman
• 金额: $ 24.64万
• 依托单位: Texas A&M University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1325683&HistoricalAwards=false
• 关键词: Collaborative; Research; Elements; extinction; Exploring

Biologists warn that the current degradation and fragmentation of ecosystems will lead to extinctions long into the future -- a process dubbed 'Extinction debt' --but making accurate predictions requires a much better understanding of how extinctions occur over long-term time scales. This project will dissect the Plio-Pleistocene extinction event (1-2 Myr) in the southwestern Caribbean (SWC) to examine the relationship between environmental perturbation and extinction rate. During the Plio-Pleistocene event, extinction rates peaked between 35 and 100% in a variety of marine taxa across the Caribbean. Taxa better adapted to nutrient-rich conditions were impacted most. Thus, the extinction is often attributed to declining planktic nutrients in Caribbean water due to isolation from the Pacific after the closure of the Central American Isthmus. The extinctions lagged closure by 1-2 Myr, however, leading some researchers to attribute increased extinction rates to climate change associated with the onset of northern hemisphere glaciation. This study will integrate biotic and geochemical data to reveal the direct causes of the Caribbean extinction event and evaluate the evidence for the perceived delay using established and new paleoenvironmental proxies and the unprecedented breadth of sampling and depth of taxonomic analyses provided by the Panama Paleontology Project (PPP). Three hypotheses will be tested: (1) Doomed taxa survived in nutrient-rich refugia that persisted after Isthmus closure; extinction occurred when refugia diminished sufficiently. (2) Extinction was driven by cooling related to northern hemisphere glaciation. (3) Temporary survival of doomed taxa was unrelated to changes in nutrients or temperature, suggesting stochastic processes were responsible. To accomplish this, we will generate high-resolution stable isotopic (18O/16O, 13C/12C) profiles of ~90 gastropod shells from 26 fossil localities in the SWC dating between 5 and 1.4 Ma, supplemented by clumped isotope (13C18O/12C16O) and trace element (P/Ca, Sr/Ca, Ba/Ca) analyses, to determine past local temperature and nutrient availability. This project will be the first to establish a well-constrained environmental system using the Tropical American fossil record and multiple high-resolution geochemical proxies to test a range of evolutionary hypotheses. These include the processes responsible for speciation, extinction, niche expansion, and evolutionary maintenance of sexual reproduction. Uniting biotic data with detailed paleoenvironmental data will reveal the root cause of the most geologically recent marine extinction and provide a real-world example with which to test models of the process of large-scale biodiversity loss. The modern anthropogenic fragmentation of natural habitats and populations mirrors the refugia that are purported to have delayed the extinction of SWC taxa in the Pliocene. Our data will evaluate this hypothesis and demonstrate whether this loss in biodiversity was directly related to environmental changes.The project will integrate a Panama-based field experience into the undergraduate capstone course of the Environmental Programs in Geoscience at Texas A&M University (TAMU). Students will work in groups and conduct paleobiology and stable isotope research on samples they collect in Panama, and sample and analyze at TAMU. In addition to presenting results, students will write, peer-review, and revise research papers. The project will train a post-doctoral fellow and graduate student in interdisciplinary science and research mentoring. Finally, research findings will be presented at major national and international meetings and published in premier journals.

生物学家警告说，当前的生态系统的降解和分散化将导致未来的灭绝 - 这是一种称为“灭绝债务”的过程 - 但进行准确的预测需要更好地了解灭绝如何在长期时间范围内发生。该项目将剖析西南加勒比海（SWC）中的Plio-pelyperencene灭绝事件（1-2 MYR），以检查环境扰动与灭绝率之间的关系。在Plio-Pleistecene事件中，整个加勒比海地区各种海洋分类群中的灭绝率在35％至100％之间达到峰值。更好地适应营养丰富的疾病的类群受到最大的影响。因此，灭绝通常归因于中美洲地峡关闭后与太平洋分离的加勒比海岩质营养素的下降。然而，灭绝的闭合滞后于1-2 MYR，导致一些研究人员将灭绝率归因于与北半球冰川发作相关的气候变化。这项研究将整合生物和地球化学数据，以揭示加勒比灭绝事件的直接原因，并使用已建立和新的古环境代理以及巴拿马古生物学项目（PPP）提供的分类分析的采样和分类分析的前所未有的广度来评估所感知到的延迟的证据。将检验三个假设：（1）注定要在及地峡是闭合后持续存在的营养丰富的避难所中幸存下来；当弹药足够减少时，就会灭绝。 （2）灭绝是由与北半球冰川相关的冷却驱动的。 （3）注定分类群的暂时存活与养分或温度的变化无关，这表明随机过程是造成的。 To accomplish this, we will generate high-resolution stable isotopic (18O/16O, 13C/12C) profiles of ~90 gastropod shells from 26 fossil localities in the SWC dating between 5 and 1.4 Ma, supplemented by clumped isotope (13C18O/12C16O) and trace element (P/Ca, Sr/Ca, Ba/Ca) analyses, to determine past local temperature and nutrient可用性。该项目将是第一个使用热带美国化石记录和多个高分辨率地球化学代理建立良好约束环境系统的项目，以检验一系列进化假设。其中包括负责物种形成，灭绝，利基扩展和有性繁殖的进化维持的过程。将生物数据与详细的古环境数据团结起来将揭示地质上最近期海洋灭绝的根本原因，并提供了一个现实世界中的示例，以测试大规模生物多样性损失过程的模型。自然栖息地和种群的现代人为碎片反映了据称延迟SWC分类单元在上新世中灭绝的避难所。我们的数据将评估这一假设，并证明生物多样性中的这种损失是否与环境变化直接相关。该项目将将基于巴拿马的现场经验整合到德克萨斯A＆M University（TAMU）地球科学环境计划的本科生盖层。学生将分组工作，并对他们在巴拿马收集的样品进行古生物学和稳定的同位素研究，并在TAMU进行采样和分析。除了提出结果外，学生还将撰写，同行评审和修改研究论文。该项目将培训跨学科科学与研究指导的博士后研究员和研究生。最后，研究结果将在主要的国家和国际会议上提出，并在总理期刊上发表。