“复活分子”在穿越生物大灭绝过程中的实质是什么？

ESSENCE OF LAZARUS TAXA ACROSS MASS EXTINCTION

复活分子是指地层记录中一度消失、后来复现且未发生明显变化的特殊分类单元。本文将复活分子区分为狭义(穿越灭绝事件)和广义(平常时期)的两类;并认为不同型式灭绝事件后的复活分子存在差异,表明其与灭绝强度有关。本文再次讨论复活分子的不同概念及其意义,并对避难所提出新的认识,强调复活分子的实质是灭绝期缩减居群大小与分布的极端稀疏分类单元,识别其生物因素尤为重要。以华南奥陶-志留纪交界期的华夏正形贝腕足动物群的一个采样点为例,说明稀疏种对多样性的贡献颇为关键,只有依靠大量的采样与深入的系统古生物研究,才能识别;探索和发现复活分子的关键在于采样和系统学研究的深入程度;建议应更加客观地认识复活分子的宏演化意义。

Lazarus taxa are a kind of special taxa which disappear from the stratigraphic record for a certain duration particularly during a mass extinction, then reappear without significant morphological changes when the disaster was over. Here Lazarus taxa are further differentiated into strict type （across mass extinction） and general type （back- ground time）. The difference between Lazarus taxa of different extinction events suggests that the intensity of the biotic crisis plays an important role on the frequency, the taxonomic level and the absence duration of Lazarus taxa. This study i） discusses the fundamental concepts related to Lazarus taxa and their significance, ii） proposes a new explanation for refugee, and, iii） emphasizes the essence of Lazarus taxa that were extremely rare taxa, those that drastically decreased their population size during the crisis, further suggesting that the biotic factors are very important to the existence and recognition of Lazarus taxa. With the earliest Silurian brachiopod Cathaysiorthis fauna as a reference example from South China, it is confirmed that rare species among benthic fauna are crucial to its overall diversity. It is also observed that rare species could be obtained through intense sampling and systematic palaeontological study, both of which are also particularly important to- wards the investigation of Lazarus taxa. Hence, the macroevolutionary implication of Lazarus taxa should be evaluated with great caution.