Data from: Homage to Bateman: sex roles predict sex differences in sexual selection

Classic sex role theory predicts that sexual selection should be stronger in males in taxa showing conventional sex roles and stronger in females in role reversed mating systems. To test this very central prediction and to assess the utility of different measures of sexual selection, we estimated sexual selection in both sexes in four seed beetle species with divergent sex roles using a novel experimental design. We found that sexual selection was sizeable in females and the strength of sexual selection was similar in females and males in role-reversed species. Sexual selection was overall significantly stronger in males than in females and residual selection formed a substantial component of net selection in both sexes. Furthermore, sexual selection in females was stronger in role-reversed species compared to species with conventional sex roles. Variance-based measures of sexual selection (the Bateman gradient and selection opportunities) were better predictors of sexual dimorphism in reproductive behavior and morphology across species compared to trait-based measures (selection differentials). Our results highlight the importance of using assays that incorporate components of fitness manifested after mating. We suggest that the Bateman gradient is generally the most informative measure of the strength of sexual selection in comparisons across sexes and/or species.经典性角色理论预测，在展现常规性角色的类群中，性选择在雄性中更强；而在性角色反转的交配系统中，性选择在雌性中更强。为验证这一核心预测，并评估不同性选择测度的实用性，我们采用全新实验设计，对4个性角色存在分化的种子甲虫物种的两性性选择进行了估算。研究发现，雌性的性选择强度可观；在性角色反转的物种中，雌雄两性的性选择强度相近。总体而言，雄性的性选择强度显著高于雌性；残差选择构成了两性净选择的重要组成部分。此外，相较于具备常规性角色的物种，性角色反转物种中的雌性性选择强度更高。相较于基于性状的测度（选择差），基于方差的性选择测度（贝特曼梯度 (Bateman gradient) 与选择机会）能更好地预测不同物种间繁殖行为与形态特征的性二态性。本研究结果凸显了纳入交配后显现的适合度组分的实验检测手段的重要性。我们提出，在跨性别或跨物种的性选择强度比较中，贝特曼梯度通常是最具信息量的性选择测度指标。