Data from: Developmental plasticity affects sexual size dimorphism in an anole lizard

While developmental plasticity has been shown to contribute to sexual size dimorphism (SSD) in laboratory studies, its role in shaping SSD variation in wild vertebrate populations is unclear. Here we use a field study and a laboratory experiment to show that resource availability influences the degree of SSD among insular populations of Anolis sagrei lizards in the Bahamas. Total amounts of food biomass explained variation in male, but not female, body size on six Bahamian islands, giving rise to significant differences in SSD. Laboratory experiments on a captive colony of A. sagrei confirmed that variation in SSD was mediated by the effects of prey biomass on developmental plasticity in males, but not females. Indeed, males grew faster and attained larger sizes as adults under high food treatments than under restricted diets, whereas adult females retained similar body sizes under both conditions. Our results indicate that the amount of food available can influence inter-sexual variation in body size within a vertebrate species. Sex-specific developmental plasticity may be favored if it allows individuals to take advantage of varying levels of food opportunities offered by different habitats, by reducing competition between the sexes. As such, plasticity in response to food availability may have played a role in the invasion success of A. sagrei. This study adds to our growing understanding of the effect of resource availability in shaping SSD in reptiles and lends further support to the condition-dependence hypothesis, according to which the larger sex should display greater plasticity in growth in response to environmental conditions.已有实验室研究表明发育可塑性（developmental plasticity）会影响性大小二态性（sexual size dimorphism, SSD），但野外脊椎动物种群中SSD的变异究竟受何种因素塑造，目前仍不明确。本研究结合野外调查与室内实验，证实资源可获得性会调控巴哈马群岛萨氏安乐蜥（Anolis sagrei）岛屿种群的SSD程度。在巴哈马的6座岛屿上，总食物生物量能够解释雄性个体的体型变异，但无法解释雌性个体的体型变异，由此引发了SSD的显著差异。针对萨氏安乐蜥人工饲养种群的室内实验进一步验证，SSD的变异是通过猎物生物量对雄性而非雌性发育可塑性的介导作用实现的。具体而言，高食物供给条件下，雄性个体生长速率更快，成年后体型也更大；而雌性个体在两种饲喂条件下的成年体型无显著差异。本研究结果表明，可获得的食物总量能够影响脊椎动物物种内的两性体型差异。若性别特异性的发育可塑性可帮助个体利用不同栖息地提供的差异化食物资源水平，同时降低两性间的竞争，则该类可塑性将受到自然选择的青睐。据此，响应食物可获得性的发育可塑性可能在萨氏安乐蜥的入侵成功过程中发挥了作用。本研究深化了学界对资源可获得性调控爬行动物SSD的认知，并为条件依赖假说（condition-dependence hypothesis）提供了进一步的实验支撑——该假说指出，体型更大的性别在响应环境条件变化时，其生长可塑性也会更强。