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 allomet...

实证研究表明，针对雌雄体型异速标度的伦施法则（Rensch's rule）——即某一演化支（clade）内雄性间的体型分化程度高于雌性——并非普适性规律。事实上，数量遗传学理论指出，经历历史上更强定向选择的性别，其体型的种间方差会更大。因此，通过分析相关演化支中雌雄体型异速标度与性体型二态性（sexual size dimorphism, SSD）之间的协方差模式，可检验性体型二态性宏观演化趋势的这一因果假说。我们汇编了已发表的两栖纲体型估算数据，该类群普遍表现为雌性偏倚的性体型二态性，旨在探究不同演化支的异速标度模式与性体型二态性的变异情况。研究结果显示，随着某一科的性体型二态性程度升高，该科内物种种间体型变异更大的性别会逐渐转为雌性。这一结果不支持伦施法则，并表明对雌性的选择是驱动两栖动物异速生长……