Data from: A shift in the long-term mode of foraminiferan size evolution caused by the end-Permian mass extinction

Size is among the most important traits of any organism, yet the factors that control its evolution remain poorly understood. In this study, we investigate controls on the evolution of organismal size using a newly compiled database of nearly 25,000 foraminiferan species and subspecies spanning the past 400 million years. We find a transition in the pattern of foraminiferan size evolution from correlation with atmospheric pO2 during the Paleozoic (400-250 Mya) to long-term stasis during the post-Paleozoic (250 Mya to present). Thus, a dramatic shift in the evolutionary mode coincides with the most severe biotic catastrophe of the Phanerozoic (543 Mya to present). Paleozoic tracking of pO2 was confined to Order Fusulinida, whereas Paleozoic lagenides, miliolids, and textulariids were best described by the stasis model. Stasis continued to best describe miliolids and textulariids during post-Paleozoic time, while random walk was the best supported mode for the other diverse orders. The shift in evolutionary dynamics thus appears to have resulted primarily from the selective elimination of fusulinids at the end of the Permian Period. These findings illustrate the potential for mass extinction to alter macroevolutionary dynamics for hundreds of millions of years.

体型是所有生物体最为核心的性状之一，然而调控其演化的关键机制迄今仍未得到充分阐释。本研究依托新构建的涵盖距今4亿年以来近25000种有孔虫（foraminiferan）物种及亚种的数据库，探究调控生物体体型演化的关键机制。研究发现，有孔虫体型演化的模式存在显著转变：在距今4亿至2.5亿年的古生代（Paleozoic），其体型演化与大气氧分压（pO2）呈显著相关；而在古生代之后（post-Paleozoic），则转为长期的停滞演化模式。这一演化模式的剧烈转变，与显生宙（Phanerozoic）发生的最严重生物集群灭绝事件恰好重合。古生代时期，仅纺锤虫目（Order Fusulinida）的类群其体型演化与大气氧分压相关；而古生代的瓶虫类（lagenides）、粟虫类（miliolids）及编织虫类（textulariids），其体型演化则更符合停滞演化模型。古生代之后，粟虫类与编织虫类仍以停滞演化模式为最优解释，其余多样类群则以随机游走模型（random walk）作为最具支撑力的演化模式。由此可见，演化动力学的转变主要源于二叠纪（Permian）末期纺锤虫类的选择性灭绝。本研究结果表明，集群灭绝事件能够在数亿年的尺度上重塑宏观演化的动态格局。