Evolution and paleoecology of the Late Ordovician North American epicontinental brachiopod fauna through diversification and environmental change

晚奥陶世北美陆表腕足动物群通过多样化和环境变化的演化和古生态

• 批准号: RGPIN-2020-07072
• 负责人: Sproat, Colin
• 金额: $ 1.82万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741271
• 关键词: Evolution; paleoecology; Late; Ordovician; North

During the Ordovician period (485-444 million years ago), the Great Ordovician Biodiversification Event marked the rise of the filter feeding Paleozoic Fauna during a sustained sea level rise and greenhouse climate regime. This was interrupted by a glaciation causing the Late Ordovician Mass Extinction that devastated the shallow marine ecosystem. Global biodiversification trends during this critical interval in the history of life are becoming clearer, but evolutionary innovations in individual lineages and the changes within benthic communities during these events are only beginning to be studied. We do not understand, for example, what characteristics made some lineages more successful while others became extinct. We do know, however, that brachiopods were among the most abundant and diverse elements of the marine ecosystem throughout these events making them an excellent proxy for changes in the shallow marine ecosystem as a whole. My research program will take a quantitative approach to studying evolutionary trends in time and space and understanding the community-level changes behind these major biodiversification and extinction events. Students will use a hands-on specimen-based approach to build morphometric (shell measurement) and ecological (species abundance, presence/absence) databases. These databases will be examined using multivariate statistical methods (e.g. principal component analysis, non-metric dimensional scaling) to search for overarching trends within individual brachiopod lineages and regional collections of ecological data. Initially, my research will focus on the pre-extinction Ordovician biodiversification as fossil brachiopods from that interval are best preserved and most abundant. Brachiopods from the Interlake of Manitoba and areas near Lake Simcoe and Manitoulin Island in Ontario will be used to compare trends in two different settings. During the Ordovician, southern Ontario was subject to regular intense tropical storms disrupting the shallow marine environment and rapidly rising sea level. At the same time Manitoba was located near the equator in a relatively stable intracratonic setting and quiescent environment, but the fauna may have had to adapt to a stagnant water column with periods of poor circulation in the water column. With a better understanding of how benthic organisms such as brachiopods adapted through these major evolutionary shifts during intervals of sea level change, we may be able to better predict how the modern shallow marine ecosystem will respond to climate change and sea level rise. While modern biological studies have documented the short-term effects of climate change and sea level rise, only the fossil record can show the effects of environmental change on the thousand- to million-year timescale. As Canada continues to plan for the effects of climate change in the future, this research will provide insight as to how the shallow marine ecosystem adapts to environmental shifts.

在奥陶纪时期（485-4.44亿年前），大奥陶纪的生物多样性事件标志着在持续的海平面上升和温室气候状态下，过滤器喂养古生物学动物群的上升。这被冰川化所中断，导致晚期奥托维奇的巨大灭绝破坏了浅海生态系统。在生活史的这一关键间隔期间，全球生物多样性趋势变得越来越清晰，但是在这些事件期间，各个谱系的进化创新和底栖群落内部的变化才开始研究。例如，我们不明白哪些特征使某些血统更加成功，而另一些特征变得更加成功。但是，我们确实知道，在这些事件中，腕足动物是海洋生态系统中最丰富，最多样化的要素之一，这使它们成为整个浅海生态系统变化的绝佳代理。我的研究计划将采用一种定量方法来研究时间和空间的进化趋势，并了解这些主要的生物多元化和灭绝事件背后的社区级别的变化。学生将使用基于动手标本的方法来构建形态计量学（外壳测量）和生态（物种丰度，存在/缺失）数据库。这些数据库将使用多元统计方法（例如主组件分析，非金属尺寸缩放）进行检查，以搜索单个Brachiopod谱系中的总体趋势和生态数据的区域集合。最初，我的研究将重点放在前灭台的奥陶纪生物多样性上，因为该间隔的化石腕足是最好的保存和最丰富的。曼尼托巴省（Manitoba）的交叉点和安大略省曼尼托林岛附近的地区的brachiopods将用于比较两种不同环境中的趋势。在奥陶纪期间，安大略省南部受到定期强烈的热带风暴，破坏了浅海环境并迅速上升的海平面。同时，曼尼托巴省以相对稳定的裂纹内环境和静止环境位于赤道附近，但动物群可能不得不适应停滞的水柱，水柱中的循环不良。有了更好地了解在海平面变化间隔期间通过这些重大进化转变改编的底栖生物，我们可能能够更好地预测现代浅水海洋生态系统将如何响应气候变化和海平面上升。尽管现代生物学研究已经记录了气候变化和海平面上升的短期影响，但只有化石记录才能显示出环境变化对数千至百万年度时间表的影响。随着加拿大未来气候变化的影响，这项研究将提供有关浅海生态系统如何适应环境转变的见解。