Survival and re-diversification of pentameride brachiopod fauna from Late Ordovician to early Silurian

晚奥陶世至早志留世五肢腕足动物群的生存和再多样化

• 批准号: RGPIN-2019-04747
• 负责人: Jin, Jisuo
• 金额: $ 3.33万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714907
• 关键词: Survival; re; diversification; pentameride; brachiopod

As a group of dominant marine sea shells in the Ordovician and Silurian periods (485419 million years ago), brachiopods experienced drastic diversity fluctuations through greenhouse-icehouse climate changes in the Late Ordovician-early Silurian. The Pentameridine group underwent a moderate radiation during the Late Ordovician but became nearly extinct during the Late Ordovician Mass Extinction, reduced to a single genus Brevilamnulella. By the early Silurian, pentameride radiated rapidly to dominate the shallow seas. Thus the origin and early evolution of the pentameridines constituted a striking case of near total extinction but rapid re-diversification. Earliest Silurian pentamerides showed rapid morphological transformations to adapt to a wide range of water depth and substrate conditions, represented by three major groups (the virgianids, stricklandiids, and clorindids). The oldest Stricklandia and Clorinda in the earliest Silurian show morphological similarities to Brevilamnulella, with younger stricklandioids evolving towards a large shell with a wide hingeline to adapt to relatively deep-water, soft muddy substrate. The clorindioids retained a relatively small, globular shell to specialize in living in low-energy, deep-water, outer-shelf environment. The early Silurian diversification of pentamerides from Brevilamnulella is interpreted as rapid exploration of a wide range ecological niches from shallow, high-energy settings to deep and quiet outer-shelf environments, left largely “empty” by the Late Ordovician mass extinction event. The great morphological plasticity in earliest Silurian pentamerides has made it difficult to quantitatively study their initial diversification. This study will examine the morphological variability among the Hirnantian Brevilmnulella and the earliest Silurian pentamerides to determine their phylogenetic relationships among the ancestral Brevilamnulella and the earliest Silurian virgianids, stricklandioids, and clorindioids, and to explore the ecological factors related to speciation. To test the hypothesis that the extinction survivor Brevilamnulella gave rise to a multitude of pentameride brachiopods that became the dominant Silurian “sea shells”, research collaborations with several international colleagues will help gain access to key pentameride collections from Canada, the UK, North Greenland, and South China, ranging from the Late Ordovician to early Silurian. A multi-technique approach (serial sectioning, moulds and cast, and micro-CT scanning) will be used to build a reliable morphological database. The data will then be analyzed using multivariate and cladistic methods to reveal evolutionary trends, phylogenetic relationships, and paleoecological implications. This type of study will help shed light on the evolutionary processes when global biodiversity undergoes a drastic boom-bust-recovery cycle.

作为一群在奥陶纪和志留纪时期（4854.19亿年前）中的一群占主导地位的海洋贝壳，腕足动物通过晚期奥托维奇时期的西尔鲁里亚人的温室气候变化经历了急剧的多样性波动。五角胺群在晚期奥陶纪期间经历了现代的辐射，但在奥陶纪晚期灭绝期间几乎灭绝，降低到单一的Brevilamnulella属。在早期的志留纪，五角甘酯迅速辐射以统治浅海。五甲生殖素的起源和早期进化构成了一个接近总延伸但快速变化的罢工案例。 最早的志留纪五聚会显示出快速的形态转化，以适应以三个主要组（virgianid，stricklandids和clorindids）为代表的广泛水深和底物条件。最早的志留纪（Lilurian）中最古老的Stricklandia和Clorinda表现出与Brevilamnulella的形态学相似性，年轻的Stricklandioids朝着具有宽大的蓝壳的大壳演变，可适应相对较深的含水，柔软的泥泞的底物。克洛尼德人保留了一个相对较小的全球外壳，专注于生活在低能，深水，外架环境中。从Brevilamnulella的五聚会的早期志留纪多样化被解释为快速探索从浅层，高能环境到深层和安静的外部架子环境，由晚期奥托维奇质量扩展事件留下的大“空”。 最早的志留纪五焦油中最早的形态可塑性使得很难定量研究其初始多样化。这项研究将检查腰hirnantian brevilmnullella和最早的志留纪五焦油的形态变异性，以确定它们之间的系统发育关系，以及祖先的Brevillamnulella和最早的志留素绒毛膜，斯特里克兰德病毒和cr虫类药物和cr虫类药物，以及与生态因素有关。 为了检验以下假设：扩展幸存者brevilamnulella产生了多种五丁酰胺类腕足动物，成为主要的志留纪“贝壳”，与几位国际同事的研究合作将有助于获得从加拿大，英国，北绿地，北绿地和南方的order orderian的orderianian竞争的重心集。多技术方法（串行切片，模具和铸造以及微CT扫描）将用于构建可靠的形态数据库。然后，将使用多元和cladistic方法对数据进行分析，以揭示进化趋势，系统发育关系和古生态学意义。当全球生物多样性经历剧烈的爆炸性灾难恢复周期时，这类研究将有助于阐明进化过程。