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.

尽管已有实验室研究证实发育可塑性（developmental plasticity）会对性大小二态性（sexual size dimorphism, SSD）产生影响，但野生脊椎动物种群中SSD的变异成因仍尚不明确。本研究结合野外调查与室内控制实验，证实资源可获得性会影响巴哈马群岛萨氏安乐蜥（Anolis sagrei）的岛屿种群间SSD程度差异。我们在巴哈马的6座岛屿上开展研究，发现食物生物量总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，由此造成了SSD的显著差异。针对人工圈养的萨氏安乐蜥种群开展的室内控制实验进一步证实，SSD的变异是通过猎物生物量对雄性发育可塑性的调控作用实现的，而非雌性。具体而言，在高食物供给条件下，雄性个体生长速度更快，最终成年体型显著大于低食物限制组；而雌性个体在两种饲喂条件下的成年体型并无显著差异。本研究结果表明，可获取的食物总量能够影响脊椎动物物种内的两性体型变异。若个体能够通过降低两性间的种内竞争，利用不同生境所提供的食物资源水平差异，那么性别特异性的发育可塑性将更受自然选择青睐。据此而言，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重要作用。本研究增进了学界对资源可获得性调控爬行动物SSD的认知，并进一步为条件依赖假说提供了支持：该假说认为，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。