Data from: Selection in a fluctuating environment and the evolution of sexual dimorphism in the seed beetle Callosobruchus maculatus

Temperature changes in the environment, which realistically include environmental fluctuations, can create both plastic and evolutionary responses of traits. Sexes might differ in either or both of these responses for homologous traits, which in turn has consequences for sexual dimorphism and its evolution. Here we investigate both immediate changes in and the evolution of sexual dimorphism in response to a changing environment (with and without fluctuations) using the seed beetle Callosobruchus maculatus. We investigate sex differences in plasticity and also the genetic architecture of body mass and developmental time dimorphism to test two existing hypothesis on sex differences in plasticity (adaptive canalization hypothesis and condition dependence hypothesis). We found a decreased sexual size dimorphism in higher temperature and females responded more plastically than males, supporting the condition dependence hypothesis. However, selection in a fluctuating environment altered sex specific patterns of genetic and environmental variation, indicating support for the adaptive canalization hypothesis. Genetic correlations between sexes (r_MF) were affected by fluctuating selection, suggesting facilitated independent evolution of the sexes. Thus, the selective past of a population is highly important for the understanding of the evolutionary dynamics of sexual dimorphism.

包含环境波动在内的自然环境温度变化，可引发性状的可塑性响应与进化响应。对于同源性状（homologous traits）而言，两性在这两类响应中的至少一类或两类均可存在差异，进而对性二态性（sexual dimorphism）及其演化产生影响。本研究以四纹豆象（Callosobruchus maculatus）为实验材料，探究环境（分别设置有波动、无波动两种情形）变化下性二态性的即时变化与演化过程。我们通过分析体重与发育时长二态性的遗传架构，探究可塑性的性别差异，以此检验两项关于可塑性性别差异的现存假说：适应性渠化假说（adaptive canalization hypothesis）与条件依赖假说（condition dependence hypothesis）。研究结果显示，高温环境下性体型二态性有所降低，且雌性的可塑性响应强于雄性，该结果支持条件依赖假说。然而，波动环境下的选择作用改变了性别特异性的遗传与环境变异模式，表明其支持适应性渠化假说。两性间的遗传相关系数（r_MF）受波动选择的影响，这提示两性的独立演化得到了促进。综上，种群的选择历史对于理解性二态性的演化动态至关重要。