Data from: Inconsistency between different measures of sexual selection

Measuring the intensity of sexual selection is of fundamental importance in the study of sexual dimorphism, population dynamics, and speciation. Several indices, pools of individuals, and fitness proxies are used in the literature, yet their relative performances are strongly debated. Using twelve independent common lizard populations, we manipulated the adult sex ratio (ASR), a potentially important determinant of the intensity of sexual selection at a particular time and place. We investigated differences in the intensity of sexual selection, as estimated using three standard indices of sexual selection: selection gradients (β′), opportunity of selection (I), and Bateman gradients (βss), calculated for different pools of individuals and different fitness proxies. We show that results based on estimates of I were opposite to those derived from the other indices, while those based on estimates of β′ were consistent with predictions derived from knowledge about the species' mating system. In addition, our estimates of the strength and direction of sexual selection depended both on the fitness proxy used and the pool of individuals included in the analysis. These observations demonstrate inconsistencies in distinct measures of sexual selection, and underscore the need for caution when comparing studies and species.

量化性选择强度，对于性二态性、种群动态及物种形成的研究具有核心意义。现有研究文献中已采用多种性选择指标、个体分组池与适合度代理变量，但学界对其相对表现仍存在激烈争议。本研究以12个独立的普通蜥蜴种群为实验对象，对其成体性比（adult sex ratio, ASR）进行操控——成体性比是特定时空下性选择强度的潜在关键决定因素。本研究采用3种经典性选择指标：选择梯度（selection gradients, β′）、选择机会（opportunity of selection, I）与贝特曼梯度（Bateman gradients, βss），针对不同个体分组池与不同适合度代理变量开展估算，以此探究性选择强度的差异。研究结果显示，基于选择机会I的估算结果与另外两种指标的结果截然相反；而基于选择梯度β′的估算结果，则与该物种交配系统相关认知推导得出的预测相符。此外，本研究对性选择强度与方向的估算结果，同时取决于所选用的适合度代理变量，以及分析中纳入的个体分组池。上述观测结果表明，不同性选择衡量指标之间存在不一致性，同时也凸显了在开展跨研究与跨物种比较时需保持谨慎的必要性。