Data from: Effects of mass extinction and recovery dynamics on long-term evolutionary trends: a morphological study of Strophomenida (Brachiopoda) across the Late Ordovician mass extinction

Mass extinctions affect the history of life by decimating existing diversity and ecological structure and creating new evolutionary and ecological pathways. Both the loss of diversity during these events and the rebound in diversity following extinction had a profound effect on Phanerozoic evolutionary trends. Phylogenetic trees can be used to robustly assess the evolutionary implications of extinction and origination. We examine both extinction and origination during the Late Ordovician mass extinction. This mass extinction was the second largest in terms of taxonomic loss but did not appear to radically alter Paleozoic marine assemblages. We focus on the brachiopod order Strophomenida, whose evolutionary relationships have been recently revised, to explore the disconnect between the processes that drive taxonomic loss and those that restructure ecological communities. A possible explanation for this disconnect is if extinction and origination were random with respect to morphology. We define morphospace using principal coordinate analysis (PCO) of character data from 61 Ordovician-Devonian taxa and their 45 ancestral nodes, defined by a most parsimonius reconstruction in Mesquite. A bootstrap of the centroid of PCO values indicates that genera were randomly removed from morphospace by the Late Ordovician mass extinction, and new Silurian genera were clustered within a smaller previously unoccupied region of morphospace. Diversification remained morphologically constrained throughout the Silurian and into the Devonian. This suggests that the recovery from the Late Ordovician mass extinction resulted in a long-term shift in strophomenide evolution. More broadly, recovery intervals may hold clues to understanding the evolutionary impact of mass extinctions.生物大灭绝通过摧毁现存的生物多样性与生态结构、开辟全新的演化与生态路径，深刻影响地球生命的演化历程。此类灭绝事件中发生的多样性丧失，以及灭绝后生物多样性的复苏，均对显生宙（Phanerozoic）的演化趋势产生了深远影响。系统发育树可用于稳健评估灭绝与类群起源的演化意义。本研究聚焦奥陶纪晚期生物大灭绝（Late Ordovician mass extinction）期间的灭绝与类群起源过程。该次大灭绝按分类群损失量计算为地球历史上第二大灭绝事件，但并未彻底重塑古生代（Paleozoic）海洋生物群落结构。我们选取近期完成演化关系修订的扭月贝目（Strophomenida）作为研究类群，以探究驱动分类群丧失的过程与重构生态群落的过程之间存在的脱节现象。针对这一脱节现象的一种合理解释是：灭绝与起源过程与生物形态特征不存在关联性。我们基于61个奥陶纪-泥盆纪（Devonian）类群及其45个祖先节点的性状数据，借助Mesquite软件中的最简约法重建确定祖先节点后，通过主坐标分析（principal coordinate analysis, PCO）构建形态空间。对主坐标分析质心的自助法（bootstrap）检验结果显示，奥陶纪晚期生物大灭绝随机移除了形态空间内的属级类群，而志留纪（Silurian）新生的属级类群则聚集在形态空间中此前未被占据的较小区域内。在志留纪乃至泥盆纪时期，物种多样化始终受到形态空间的约束。该研究结果表明，奥陶纪晚期生物大灭绝后的复苏过程，使得扭月贝类的演化出现了长期的方向性转变。从更宏观的视角来看，生物复苏阶段或许可为理解生物大灭绝的整体演化影响提供关键线索。