Am Nat. 2020 May;195(5):899-917. doi: 10.1086/707664. Epub 2020 Mar 17.
Is speciation generally a "special time" in morphological evolution, or are lineage-splitting events just "more of the same" where the end product happens to be two separate lineages? Data on evolutionary dynamics during anagenetic and cladogenetic events among closely related lineages within a clade are rare, but the fossil record of the bryozoan genus is considered a textbook example of a clade where speciation causes rapid evolutionary change against a backdrop of morphological stasis within lineages. Here, we point to some methodological and measurement theoretical issues in the original work on . We then reanalyze a subset of the original data that can be meaningfully investigated using quantitative statistical approaches similar to those used in the original studies. We consistently fail to find variation in the evolutionary process during within-lineage evolution compared with cladogenetic events: the rates of evolution, the strength of selection, and the directions traveled in multivariate morphospace are not different when comparing evolution within lineages and at speciation events in , and genetic drift cannot be excluded as a sufficient explanation for the morphological differentiation within lineages and during speciation. Although widely considered the best example of a punctuated mode of evolution, morphological divergence and speciation are not linked in .
物种形成通常是形态进化中的“特殊时期”，还是谱系分裂事件只是“相同的情况”，只是最终结果是两个独立的谱系？在一个进化枝内密切相关谱系的发生种形成和谱系分裂事件期间的进化动态的数据很少，但苔藓动物属的化石记录被认为是谱系形成导致快速进化变化的经典范例，而谱系内的形态停滞是背景。在这里，我们指出了关于 的原始工作中的一些方法学和测量理论问题。然后，我们重新分析了原始数据的一个子集，这些数据可以使用类似于原始研究中使用的定量统计方法进行有意义的研究。我们始终未能发现谱系内进化与谱系分裂事件之间进化过程的差异：在比较谱系内进化和 中的种形成事件时，进化率、选择强度以及多元形态空间中的行进方向没有差异，并且不能排除遗传漂变是谱系内形态分化和种形成过程的充分解释。尽管被广泛认为是一个突发性进化模式的最佳范例，但形态分歧和物种形成在 中并没有联系。
