Data from: A rigorous comparison of sexual selection indexes via simulations of diverse mating systems

Sexual selection is a cornerstone of evolutionary theory, but measuring it has proved surprisingly difficult and controversial. Various proxy measures—e.g., the Bateman gradient and the opportunity for sexual selection—are widely used in empirical studies. However, we do not know how reliably these measures predict the strength of sexual selection across natural systems, and most perform poorly in theoretical worst-case scenarios. Here we provide a rigorous comparison of eight commonly used indexes of sexual selection. We simulated 500 biologically plausible mating systems, based on the templates of five well-studied species that cover a diverse range of reproductive life histories. We compared putative indexes to the actual strength of premating sexual selection, measured as the strength of selection on a simulated “mating trait.” This method sidesteps a key weakness of empirical studies, which lack an appropriate yardstick against which proxy measures can be assessed. Our model predicts that, far from being useless, the best proxy measures reliably track the strength of sexual selection across biologically realistic scenarios. The maximum intensity of precopulatory sexual selection s′max (the Jones index) outperformed all other indexes and was highly correlated with the strength of sexual selection. In contrast, the Bateman gradient and the opportunity for sexual selection were poor predictors of sexual selection, despite their continuing popularity.性选择是进化理论的基石之一，但对其进行量化却出人意料地困难且颇具争议。学界广泛使用各类替代指标开展实证研究，例如贝特曼梯度（Bateman gradient）与性选择机会（opportunity for sexual selection）。然而，目前我们尚不清楚这些指标在自然系统中预测性选择强度的可靠程度，且多数指标在理论最坏场景下表现欠佳。本研究对8种常用的性选择指标开展了严谨的对比分析：我们基于5种已被充分研究、涵盖多样化繁殖生活史的物种模板，模拟了500个符合生物学合理性的交配系统；将待评估指标与交配前性选择的实际强度进行对比，该实际强度以模拟的"交配性状"所受选择强度来衡量。该方法规避了实证研究的一项核心缺陷——此类研究缺乏可用于评估替代指标的合适标尺。我们的模型预测，最优替代指标绝非毫无用处，反而能在符合生物学现实的场景中可靠反映性选择的强度。其中，交配前性选择的最大强度s′max（琼斯指数，Jones index）优于其余所有指标，且与性选择强度呈高度相关；与之形成鲜明对比的是，尽管贝特曼梯度和性选择机会仍被广泛使用，它们对性选择的预测能力却十分有限。