Data from: Parallel evolution of nonfeeding larvae in echinoids

The switch from feeding to nonfeeding larvae is an ecologically important transformation that has evolved on several separate occasions within the echinoids. In each case, this life history transformation has been accompanied by extensive changes in larval morphology. A phylogenetic approach is used here to reconstruct these morphological changes, to begin asking why they have taken the particular forms observed, and to assess the degree of parallel transformation in separate cases. Both traditional character mapping and a less usual aggregate analysis indicate massively parallel transformations in larval morphology associated with, and only with, this particular life history transformation. Some of these parallel morphological transformations may be due to relaxed functional constraints associated with the ancestral life history mode, but many are probably the result of new functional constraints associated with the derived mode. The comparative data suggest a simple and testable model for the switch from feeding to nonfeeding larvae involving three sequential steps.

从摄食幼体到非摄食幼体的转变是一类具有重要生态学意义的演化转变，该转变在海胆类（echinoids）中已在多个独立演化事件中出现。在每一例独立演化事件中，这类生活史转变均伴随幼体形态的显著改变。本研究采用系统发育分析方法，对这些形态变化进行重构，旨在探究为何这些变化呈现出当前观测到的特定形式，并评估不同独立演化案例中平行转变的程度。无论是传统性状映射（character mapping）分析，还是较为少见的聚合分析（aggregate analysis），均揭示出幼体形态的大规模平行转变仅与该特定生活史转变相关联。其中部分平行形态转变可能源于祖先型生活史模式所关联的功能约束放松，但多数转变或许是衍生型生活史模式所带来的新功能约束的结果。本研究的比较数据提出了一个简洁且可验证的模型，用以阐释从摄食幼体到非摄食幼体的转变过程，该模型包含三个连续步骤。