Sexual dimorphism in digit lengths reflects phenotypic evolution mediated by developmental steroids. Differences in the identity of the sexually-dimorphic digit may evolve if the concentrations of sex-steroid receptors in the digit are easily modified and the initial changes have low impact on fitness. Accordingly, sexual dimorphism in digit lengths might initially originate under neutral selective regimes, being subsequently co-opted by embryonic hormonal effects on sensitive traits that are more likely to be targeted by selection. Correlated variation among sexually-dimorphic traits might therefore reflect pleiotropic hormonal modulation during development. Moreover, the identity and trend of the sexually-dimorphic digit might be evolutionarily labile even among closely-related species. We evaluated this model by assessing the identity of sexually-dimorphic digits among 11 Tropiduridae lizard species and inferring evolutionary patterns of sexual dimorphism. Assuming that digit lengths can be used as a proxy for hormonal modulation of steroid-sensitive traits during development, we tested for evolutionary associations among sexual dimorphism of digit lengths, body size and other traits that may be direct targets of sexual selection in the Tropiduridae. Sexual dimorphism in digit lengths is evolutionarily labile in the Tropiduridae, and diversity, instead of conservatism, seems to rule developmental mechanisms underlying the evolution of sexual dimorphism in digit ratios.

中文翻译：

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数字身份很重要：拟南纲蜥蜴的数字长度中性二态性的起源和演变

手指长度的性二态性反映了发育类固醇介导的表型进化。如果容易修改手指中性类固醇受体的浓度，并且最初的变化对健康的影响较小，那么性二形手指的身份差异可能会演变。因此，数位长度的性二态性可能最初起源于中性选择性机制，随后被对更易被选择靶向的敏感性状的胚胎激素作用所选择。因此，性二形性状之间的相关变异可能反映了发育过程中的多效激素调节。而且，即使在密切相关的物种中，二态性数字的身份和趋势可能在进化上不稳定。我们通过评估11种Tropiduridae蜥蜴物种中的性二态数字的身份并推断性二态性的进化模式来评估该模型。假设数字长度可以用作发育过程中激素敏感性激素激素调节的替代指标，我们测试了数字长度，身体大小和其他可能是Tropiduridae科目的直接性状的性状之间的进化联系。数位长的性二态性在蛇蛛科中是进化不稳定的，多样性而不是保守主义似乎统治着数位比性二态性进化基础的发展机制。假设数字长度可以用作发育过程中激素敏感性激素激素调节的替代指标，我们测试了数字长度，身体大小和其他可能是Tropiduridae科目的直接性状的性状之间的进化联系。数位长的性二态性在蛇蛛科中是进化不稳定的，多样性而不是保守主义似乎统治着数位比性二态性进化基础的发展机制。假设数字长度可以用作发育过程中类固醇​​敏感性特征的激素调节的代理，我们测试了数字长度，体型和其他可能是Tropiduridae科目的直接选择目标的性状之间的进化联系。数位长的性二态性在蛇蛛科中是进化不稳定的，多样性而不是保守主义似乎统治着数位比性二态性进化基础的发展机制。