Data from: Correlated evolution of allometry and sexual dimorphism across higher taxa

Empirical evidence suggests that Rensch's rule of allometric scaling of male and female body size, which states that body size divergence is greater across males than females of a clade, is not universal. In fact, quantitative genetic theory indicates that the sex under historically stronger directional selection will exhibit greater interspecific variance in size. Thus, the pattern of covariance between allometry of male and female body size and sexual size dimorphism (SSD) across related clades allows a test of this causal hypothesis for macroevolutionary trends in SSD. We compiled a dataset of published body size estimates from the amphibians, a class with predominantly female-biased SSD, to examine variation in allometry and SSD among clades. Our results indicate that females become the more size-variant sex across species in a family as the magnitude of SSD of that family increases. This rejects Rensch's rule and implicates selection on females as a driver of both amphibian allometry and SSD. Further, when we combine our data into a single analysis of allometry for the class, we find a significant non-linear allometric relationship between female and male body size. These data suggest that allometry changes significantly as a function of size. Our results illustrate that the relationship between female and male size varies both with the degree of sexual dimorphism and body size of a clade.现有实证研究表明，针对雌雄体型异速生长的伦施法则（Rensch's rule）——即某一演化分支内雄性间的体型分化程度大于雌性——并非普适规律。事实上，定量遗传学理论指出，长期经受更强定向选择的性别，其体型的种间方差会更大。因此，相关演化分支中雌雄体型异速生长与性大小二态性（SSD）之间的协变模式，可用于检验性大小二态性宏观演化趋势的这一因果假说。我们收集了已发表的两栖类体型数据——两栖纲的性大小二态性多为雌性偏倚——以探究不同演化分支间的异速生长与性大小二态性的变异情况。研究结果显示，随着某一科的性大小二态性程度升高，该科内各物种种间体型变异更大的性别会变为雌性。这一结果驳斥了伦施法则，并表明对雌性的选择是两栖类异速生长与性大小二态性的共同驱动因素。此外，当我们将所有数据整合为针对两栖纲的统一异速生长分析时，发现雌雄体型间存在显著的非线性异速生长关系。这些数据表明，异速生长模式会随体型大小发生显著变化。本研究结果表明，雌雄体型间的关系既随演化分支的性二态程度变化，也随其体型大小改变。