Institute of Analytics and Data Science, University of Essex, Colchester, UK.
School of Life Sciences, University of Essex, Colchester, UK.
Nature. 2020 Dec;588(7839):636-641. doi: 10.1038/s41586-020-3003-4. Epub 2020 Dec 9.
The hypothesis that destructive mass extinctions enable creative evolutionary radiations (creative destruction) is central to classic concepts of macroevolution. However, the relative impacts of extinction and radiation on the co-occurrence of species have not been directly quantitatively compared across the Phanerozoic eon. Here we apply machine learning to generate a spatial embedding (multidimensional ordination) of the temporal co-occurrence structure of the Phanerozoic fossil record, covering 1,273,254 occurrences in the Paleobiology Database for 171,231 embedded species. This facilitates the simultaneous comparison of macroevolutionary disruptions, using measures independent of secular diversity trends. Among the 5% most significant periods of disruption, we identify the 'big five' mass extinction events, seven additional mass extinctions, two combined mass extinction-radiation events and 15 mass radiations. In contrast to narratives that emphasize post-extinction radiations, we find that the proportionally most comparable mass radiations and extinctions (such as the Cambrian explosion and the end-Permian mass extinction) are typically decoupled in time, refuting any direct causal relationship between them. Moreover, in addition to extinctions, evolutionary radiations themselves cause evolutionary decay (modelled co-occurrence probability and shared fraction of species between times approaching zero), a concept that we describe as destructive creation. A direct test of the time to over-threshold macroevolutionary decay (shared fraction of species between two times ≤ 0.1), counted by the decay clock, reveals saw-toothed fluctuations around a Phanerozoic mean of 18.6 million years. As the Quaternary period began at a below-average decay-clock time of 11 million years, modern extinctions further increase life's decay-clock debt.
破坏性的大规模灭绝使生物能够进行创造性的进化辐射（创造性破坏）的假设是经典宏观进化概念的核心。然而，灭绝和辐射对物种共存的相对影响尚未在整个显生宙时代直接进行定量比较。在这里，我们应用机器学习生成显生宙化石记录的时间共存结构的空间嵌入（多维排序），涵盖 171,231 个嵌入物种在古生物学数据库中的 1,273,254 个出现。这使得我们能够使用与世俗多样性趋势无关的度量标准，同时比较宏观进化中断。在 5%最重要的中断时期中，我们确定了“五大”大规模灭绝事件、七个额外的大规模灭绝事件、两个大规模灭绝-辐射事件和 15 个大规模辐射事件。与强调灭绝后辐射的叙述相反，我们发现比例上最可比的大规模辐射和灭绝（例如寒武纪大爆发和二叠纪末大灭绝）在时间上通常是分离的，这驳斥了它们之间存在任何直接因果关系的说法。此外，除了灭绝之外，进化辐射本身也会导致进化衰退（模型化的共存概率和接近零时物种的共享分数），我们将这个概念描述为破坏性创造。通过衰退时钟直接测试超过宏观进化衰退阈值的时间（两个时间之间的物种共享分数≤0.1），揭示了围绕显生宙平均值 1860 万年的锯齿形波动。由于第四纪的开始时间为 1100 万年的平均衰退时钟时间以下，现代灭绝进一步增加了生命的衰退时钟债务。
