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），奥陶纪生物多样性大事件标志着在海平面持续上升和温室气候条件下古生代滤食动物群的崛起。这一过程被冰川作用打断，冰川作用导致奥陶纪晚期大规模灭绝，摧毁了浅海生态系统。生命史上这一关键时期的全球生物多样性趋势正变得越来越清晰，但个体谱系的进化创新以及这些事件期间底栖群落内的变化才刚刚开始研究。例如，我们不明白哪些特征使某些谱系更加成功，而另一些谱系却灭绝了。然而，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和最多样化的元素之一，这使它们成为整个浅海生态系统变化的极好代表。我的研究计划将采用定量方法来研究时间和空间的进化趋势，并了解这些重大生物多样性和灭绝事件背后的社区层面的变化。学生将使用基于标本的实践方法来构建形态测量（贝壳测量）和生态（物种丰度、存在/不存在）数据库。这些数据库将使用多元统计方法（例如主成分分析、非度量维度缩放）进行检查，以搜索个体腕足动物谱系和区域生态数据集合中的总体趋势。最初，我的研究将集中在灭绝前的奥陶纪生物多样性，因为该时期的腕足动物化石保存最完好且最丰富。来自马尼托巴省因特湖以及安大略省锡姆科湖和马尼图林岛附近地区的腕足动物将被用来比较两种不同环境中的趋势。在奥陶纪期间，安大略省南部经常遭受强烈的热带风暴的影响，破坏了浅海环境并导致海平面迅速上升。同时，马尼托巴省位于赤道附近，处于相对稳定的克拉通内环境和静止的环境中，但动物群可能不得不适应停滞的水柱，水柱中存在循环不良的时期。通过更好地了解腕足动物等底栖生物如何适应海平面变化期间的这些重大进化转变，我们也许能够更好地预测现代浅海生态系统将如何应对气候变化和海平面上升。虽然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环境变化对数千年至数百万年时间尺度的影响。随着加拿大继续规划未来气候变化的影响，这项研究将为浅海生态系统如何适应环境变化提供见解。