State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China.
Department of Marine Organism Taxonomy & Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Sci Adv. 2024 Aug 9;10(32):eadj8223. doi: 10.1126/sciadv.adj8223. Epub 2024 Aug 7.
There is a strong relationship between metazoan body size and extinction risk. However, the size selectivity and underlying mechanisms in foraminifera, a common marine protozoa, remain controversial. Here, we found that foraminifera exhibit size-dependent extinction selectivity, favoring larger groups (>7.4 log cubic micrometer) over smaller ones. Foraminifera showed significant size selectivity in the Guadalupian-Lopingian, Permian-Triassic, and Cretaceous-Paleogene extinctions where the proportion of large genera exceeded 50%. Conversely, in extinctions where the proportion of large genera was <45%, foraminifera displayed no selectivity. As most of these extinctions coincided with oceanic anoxic events, we conducted simulations to assess the effects of ocean deoxygenation on foraminifera. Our results indicate that under suboxic conditions, oxygen fails to diffuse into the cell center of large foraminifera. Consequently, we propose a hypothesis to explain size distribution-related selectivity and Lilliput effect in animals relying on diffusion for oxygen during past and future ocean deoxygenation, i.e., oxygen diffusion distance in body.
后生动物的体型大小与灭绝风险之间存在很强的关系。然而，有孔虫（一种常见的海洋原生动物）的体型选择性及其潜在机制仍存在争议。在这里，我们发现有孔虫表现出与体型相关的灭绝选择性，偏爱较大的群体（>7.4 对数立方微米）而不是较小的群体。有孔虫在瓜达卢普期-洛佩斯期、二叠纪-三叠纪和白垩纪-古近纪的灭绝事件中表现出显著的体型选择性，其中大型属的比例超过 50%。相反，在大型属比例<45%的灭绝事件中，有孔虫没有表现出选择性。由于这些灭绝事件大多与海洋缺氧事件同时发生，我们进行了模拟来评估海洋脱氧对有孔虫的影响。我们的结果表明，在缺氧条件下，氧气无法扩散到大型有孔虫的细胞中心。因此，我们提出了一个假设来解释过去和未来海洋脱氧过程中依赖扩散获取氧气的动物的体型分布相关选择性和小人国效应，即氧在体内的扩散距离。
