Department of Geoscience, University of West Georgia, Carrollton, GA 30118, USA.
Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK.
Curr Biol. 2020 May 4;30(9):1672-1679.e3. doi: 10.1016/j.cub.2020.02.054. Epub 2020 Mar 19.
Quantifying morphological evolution is key to determining the patterns and processes underlying the origin of phyla. We constructed a hierarchical morphological character matrix to characterize the radiation and establishment of echinoderm body plans during the early Paleozoic. This showed that subphylum-level clades diverged gradually through the Cambrian, and the distinctiveness of the resulting body plans was amplified by the extinction of transitional forms and obscured by convergent evolution during the Ordovician. Higher-order characters that define these body plans were not fixed at the origin of the phylum, countering hypotheses regarding developmental processes governing the early evolution of animals. Instead, these burdened characters were flexible, enabling continued evolutionary innovation throughout the clades' history.
量化形态进化是确定门起源背后的模式和过程的关键。我们构建了一个层次形态特征矩阵，以描述早期古生代棘皮动物体节的辐射和建立。这表明亚门级别的分支在寒武纪逐渐分化，而过渡形式的灭绝和奥陶纪的趋同进化放大了由此产生的体节的独特性。定义这些体节的高级特征在门的起源时并不是固定的，这反驳了关于动物早期进化的发育过程的假说。相反，这些负担的特征是灵活的，使整个进化枝的历史能够继续进行创新。
