Decades of research on sexual selection have demonstrated that ‘conventional’ Darwinian sex roles are common in species with anisogamous gametes, with those species often exhibiting male-biased sexual selection. Yet, mating system characteristics such as long-term sperm storage and polyandry have the capacity to disrupt this pattern. Here, these ideas were explored by quantifying sexual selection metrics for the western diamond-backed rattlesnake (Crotalus atrox). A significant standardized sexual selection gradient was not found for males (β_SS = 0.588, p = 0.199) or females (β_SS = 0.151, p = 0.664), and opportunities for sexual selection (I_s) and selection (I) did not differ between males (I_s = 0.069, I = 0.360) and females (I_s = 0.284, I = 0.424; both p > 0.05). Furthermore, the sexes did not differ in the maximum intensity of precopulatory sexual selection (males: s′_max = 0.155, females: s′_max = 0.080; p > 0.05). Finally, there was no evidence that male snout–vent length, a trait associated with mating advantage, is a target of sexual selection (p > 0.05). These results suggest a lack of male-biased sexual selection in this population. Mating system characteristics that could erode male-biased sexual selection, despite the presence of conventional Darwinian sex roles, are discussed.

数十年的性选择研究表明，“传统”达尔文性别角色在异配配子的物种中很常见，这些物种经常表现出偏向雄性的性选择。然而，交配系统的特征，如长期精子储存和一妻多夫制，有能力破坏这种模式。在这里，通过量化西方菱背响尾蛇（ Crotalus atrox ）的性选择指标来探索这些想法。男性（ β _SS = 0.588， p = 0.199）或女性（ β _SS = 0.151， p = 0.664）没有发现显着的标准化性选择梯度，性选择（ I _s ）和选择（ I ）的机会也没有发现。男性（ I _s = 0.069， I = 0.360）和女性（ I _s = 0.284， I = 0.424；均p > 0.05）之间存在差异。此外，性别在交配前性选择的最大强度上没有差异（男性： s′ _max = 0.155，女性： s′ _max = 0.080； p > 0.05）。最后，没有证据表明雄性口鼻部长度（一种与交配优势相关的特征）是性选择的目标（ p > 0.05）。这些结果表明该人群中缺乏男性偏见的性选择。尽管存在传统的达尔文性别角色，但讨论了可能削弱男性偏见性选择的交配系统特征。