Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115, Berlin, Germany.
Evolution. 2013 Oct;67(10):2795-810. doi: 10.1111/evo.12162. Epub 2013 Jun 7.
Three main modes of extinction are responsible for reductions in morphological disparity: (1) random (caused by a nonselective extinction event); (2) marginal (a symmetric, selective extinction event trimming the margin of morphospace); and (3) lateral (an asymmetric, selective extinction event eliminating one side of the morphospace). These three types of extinction event can be distinguished from one another by comparing changes in three measures of morphospace occupation: (1) the sum of range along the main axes; (2) the sum of variance; and (3) the position of the centroid. Computer simulations of various extinction events demonstrate that the pre-extinction distribution of taxa (random or normal) in the morphospace has little influence on the quantification of disparity changes, whereas the modes of the extinction events play the major role. Together, the three disparity metrics define an "extinction-space" in which different extinction events can be directly compared with one another. Application of this method to selected extinction events (Frasnian-Famennian, Devonian-Carboniferous, and Permian-Triassic) of the Ammonoidea demonstrate the similarity of the Devonian events (selective extinctions) but the striking difference from the end-Permian event (nonselective extinction). These events differ in their mode of extinction despite decreases in taxonomic diversity of similar magnitude.
（1）随机（由非选择性灭绝事件引起）；（2）边缘（对称、选择性灭绝事件修剪形态空间的边缘）；和（3）横向（非对称、选择性灭绝事件消除形态空间的一侧）。这三种灭绝事件可以通过比较形态空间占用的三个度量标准的变化来区分：（1）主轴上范围的总和；（2）方差的总和；和（3）质心的位置。对各种灭绝事件的计算机模拟表明，形态空间中分类群的灭绝前分布（随机或正态）对差异变化的量化几乎没有影响，而灭绝事件的模式则起着主要作用。这三个差异度量标准共同定义了一个“灭绝空间”，其中不同的灭绝事件可以直接相互比较。该方法应用于菊石类的选定灭绝事件（弗拉斯期-法门期、泥盆纪-石炭纪和二叠纪-三叠纪）表明，泥盆纪事件（选择性灭绝）相似，但与二叠纪末事件（非选择性灭绝）截然不同。尽管在分类多样性上有相似的减少，但这些事件在灭绝模式上存在差异。
