Data from: Rates of morphological evolution are correlated with species richness in salamanders

The tempo and mode of species diversification and phenotypic evolution vary widely across the tree of life, yet the relationship between these processes is poorly known. Previous tests of the relationship between rates of phenotypic evolution and rates of species diversification have assumed that species richness increases continuously through time. If this assumption is violated, simple phylogenetic estimates of net diversification rate may bear no relationship to processes that influence the distribution of species richness among clades. Here we demonstrate that the variation in species richness among plethodontid salamander clades is unlikely to have resulted from simple time-dependent processes, leading to fundamentally different conclusions about the relationship between rates of phenotypic evolution and species diversification. Morphological evolutionary rates of both size and shape evolution are correlated with clade species richness, but are uncorrelated with simple estimators of net diversification that assume constancy of rates through time. This coupling between species diversification and phenotypic evolution is consistent with the hypothesis that clades with high rates of morphological trait evolution may diversify more than clades with low rates. Our results indicate that assumptions about underlying processes of diversity regulation have important consequences for interpreting macroevolutionary patterns.

生命之树各分支的物种分化（species diversification）速率与模式、表型进化速率与模式均存在广泛差异，但目前学界对这两类过程间的关联仍知之甚少。过往针对表型进化速率与物种分化速率间关联的检验研究，均假设物种丰富度会随时间持续增长。若该假设不成立，那么基于简单系统发育分析的净分化速率（net diversification rate）估算值，可能与影响支系间物种丰富度分布的过程毫无关联。本研究证实，无肺螈科（Plethodontidae）各支系的物种丰富度差异，不太可能由简单的时间依赖性过程所导致，这使得我们对表型进化速率与物种分化速率间的关联得出了截然不同的结论。体型与形态进化的形态学进化速率均与支系物种丰富度呈显著相关，但与那些假设进化速率随时间恒定的净分化速率简单估算值并无关联。物种分化与表型进化间的这种耦合关系，与"形态性状进化速率较高的支系，其物种分化程度可能高于进化速率较低的支系"这一假说相符。本研究结果表明，关于多样性调控底层过程的假设，对解读宏观进化（macroevolution）模式具有重要影响。