Data from: Evidence for complex life cycle constraints on salamander body form diversification

Metazoans display a tremendous diversity of developmental patterns, including complex life cycles composed of morphologically disparate stages. In this regard, the evolution of life cycle complexity promotes phenotypic diversity. However, correlations between life cycle stages can constrain the evolution of some structures and functions. Despite the potential macroevolutionary consequences, few studies have tested the impacts of life cycle evolution on broad-scale patterns of trait diversification. Here we show that larval and adult salamanders with a simple, aquatic-only (paedomorphic) life cycle had an increased rate of vertebral column and body form diversification compared to lineages with a complex, aquatic-terrestrial (biphasic) life cycle. These differences in life cycle complexity explain the variations in vertebral number and adult body form better than larval ecology. In addition, we found that lineages with a simple terrestrial-only (direct developing) life cycle also had a higher rate of adult body form evolution than biphasic lineages, but still 10-fold lower than aquatic-only lineages. Our analyses demonstrate that prominent shifts in phenotypic evolution can follow long-term transitions in life cycle complexity, which may reflect underlying stage-dependent constraints.后生动物（Metazoans）展现出极为丰富的发育模式多样性，其中包含由形态迥异的发育阶段所构成的复杂生活史。从这一角度而言，生活史复杂度的演化可推动表型多样性的形成。然而，生活史不同阶段间的相关性可能会对部分结构与功能的演化产生约束。尽管生活史演化具备潜在的宏观演化效应，但目前鲜有研究探讨其对大尺度性状多样化格局的影响。本研究表明，相较于拥有复杂水生-陆生两期型（biphasic）生活史的支系，具备简单仅水生幼态持续（paedomorphic）生活史的蝾螈类群，其幼体与成体的脊柱及躯体形态的演化速率显著更高。相较于幼生生境生态，生活史复杂度的差异能够更好地解释脊柱数目与成体躯体形态的变异情况。此外，本研究还发现，具备简单仅陆生直接发育（direct developing）生活史的支系，其成体躯体形态的演化速率同样高于两期型支系，但仍仅为仅水生型支系的1/10左右。本研究的分析结果表明，表型演化的显著转变可伴随生活史复杂度的长期转变，这一现象或反映了潜藏的阶段依赖性约束机制。