Data from: Bateman gradients in hermaphrodites: an extended approach to quantify sexual selection

Sexual selection is often quantified using Bateman gradients, which represent sex-specific regression slopes of reproductive success on mating success and thus describe the expected fitness returns from mating more often. Although the analytical framework for Bateman gradients aimed at covering all sexual systems, empirical studies are biased towards separate-sex organisms, probably because important characteristics of other systems remain incompletely treated. Our synthesis complements the existing Bateman gradient approach with three essential reproductive features of simultaneous hermaphrodites. First, mating in one sex may affect fitness via the opposite sex, e.g. through energetic trade-offs. We integrate cross-sex selection effects and show how they help characterizing sexually mutualistic versus antagonistic selection. Second, male and female mating successes may be correlated, complicating the interpretation of Bateman gradients. We show how to quantify the impact of
this correlation on sexual selection, and propose a Principal Component Analysis on male and female mating success to facilitate interpretation. Third, self-fertilization is accounted for by adding selfed progeny as a separate category of reproductive success to analyzes of Bateman gradients. Finally, using a worked example from the snail Biomphalaria glabrata, we illustrate how the extended analytical framework can further our understanding of sexual selection.

性选择通常通过贝特曼梯度（Bateman gradients）进行量化，该指标表征繁殖成功率对交配成功率的性别特异性回归斜率，进而描述因交配频次增加所带来的预期适合度收益。尽管贝特曼梯度的分析框架初衷是覆盖所有性别系统，但现有实证研究多偏向于雌雄异体生物，这可能是因为其他性别系统的关键特征尚未得到充分阐释。本综述结合同时性雌雄同体生物的三大核心繁殖特征，对现有贝特曼梯度分析方法进行了拓展补充。其一，某一性别的交配行为可通过另一性别途径影响适合度，例如通过能量权衡机制。我们整合了跨性选择效应，并阐明其如何助力区分性互利选择与性拮抗选择。其二，雄性与雌性的交配成功率可能存在相关性，这会增加贝特曼梯度的解读难度。我们阐释了如何量化该相关性对性选择的影响，并提出针对雌雄交配成功率开展主成分分析（Principal Component Analysis）以简化解读流程。其三，通过将自交子代作为独立的繁殖成功率类别纳入贝特曼梯度分析，即可将自体受精纳入考量范畴。最后，我们以光滑双脐螺（Biomphalaria glabrata）的实操案例为例，阐明该拓展分析框架如何进一步深化我们对性选择的认知。