Data from: Female anoles retain responsiveness to testosterone despite the evolution of androgen-mediated sexual dimorphism

1. The evolution of sexual dimorphism presents a challenge because males and females must express two phenotypes from the same underlying genome. In vertebrates, one solution to this challenge is to link the expression of shared traits to sex steroids. However, even ‘male-biased’ steroids such as testosterone (T) circulate at biologically significant levels in females, raising the question of whether sexual dimorphism evolves not only through the coupling of trait expression to T in males, but also through the decoupling of trait expression from T in females. 2. We tested these alternatives by asking whether male and female brown anoles (Anolis sagrei) respond to exogenous T in similar fashion with respect to a suite of sexually dimorphic traits: growth, skeletal morphology, resting metabolism, fat storage, dewlap size and dewlap colour. 3. First, we established the ontogeny of sexual dimorphism in a colony raised in a laboratory common garden. Next, we treated juveniles of each sex with either T implants or empty implants at 5–8 months of age, when sexual dimorphism first began to develop for most traits. 4. T stimulated growth in both sexes and largely abolished natural sex differences in growth. This effect was associated with the stimulation of resting metabolism and the diversion of energy from fat and liver stores in both sexes. T also enlarged the dewlap in both sexes, though females never developed dewlaps equal in size to those of males. Finally, T altered the brightness and saturation of the dewlap in both sexes, inducing coloration similar to that of adult males. 5. Female brown anoles retain many of the same tissue-specific responses to T that occur in males, suggesting that the evolution of androgen-mediated sexual dimorphism has been achieved largely through the coupling of trait expression to sex differences in circulating T, without an associated decoupling of trait expression from T in females.1. 性二态性（sexual dimorphism）的演化是一项极具挑战性的科学课题，因为雄性与雌性需从同一套基础基因组中表达两种截然不同的表型。在脊椎动物中，应对这一挑战的一种经典策略是将共有性状的表达与性类固醇（sex steroids）相关联。然而，即便诸如睾酮（testosterone, T）这类「雄性偏向性」类固醇，在雌性体内也会达到具有生物学意义的循环浓度，这引出了一个关键科学问题：性二态性的演化是否不仅依赖于雄性个体中性状表达与睾酮的耦合，同时也依赖于雌性个体中性状表达与睾酮的解偶联？ 2. 为检验上述两种演化假说，我们针对雄性与雌性褐安乐蜥（Anolis sagrei）展开了实验，探究二者对外源性睾酮（exogenous T）在一系列性二态性状上的响应是否具有相似性。所涉性状包括生长状况、骨骼形态、静息代谢、脂肪储存、喉扇（dewlap）尺寸与喉扇颜色。 3. 首先，我们在实验室标准化饲养环境中建立的种群内，明确了该物种性二态性的个体发生进程。随后，在幼体5至8月龄（此时大多数性状的性二态性首次开始显现）时，我们对每个性别的幼体分别植入睾酮植入物或空白植入物。 4. 睾酮可同时促进雌雄个体的生长，并大幅消除了自然状态下生长速率的性别差异。该效应与雌雄个体静息代谢的提升以及脂肪与肝脏储存中能量的调动相关。此外，睾酮可扩大雌雄个体的喉扇尺寸，尽管雌性个体的喉扇尺寸始终无法达到雄性个体的水平。最终，睾酮可改变雌雄个体喉扇的亮度与饱和度，使其体色与成年雄性个体的体色趋于一致。 5. 雌性褐安乐蜥保留了与雄性个体相同的诸多组织特异性睾酮响应，这表明雄激素（androgen）介导的性二态性演化，主要是通过将性状表达与循环睾酮的性别差异相耦合实现的，而无需在雌性个体中出现性状表达与睾酮的解偶联过程。