Body size is a key selected trait in many animal systems: larger size is sexually selected for in males because it confers a reproductive advantage during contest competition for access to females, and larger females are naturally selected for fecundity. Herein, we used radio‐telemetry to gather a large dataset of male–female interactions and DNA paternity analyses to characterize the intensity of sexual selection and the link between two body size metrics (body length and condition, the latter manipulated experimentally for males) and reproductive success in a population of puff adders Bitis arietans. Our multiple estimates of the intensity of sexual selection generally indicated that males experienced stronger sexual selection than females. However, the Bateman gradients did not differ by sex, despite the fact that males increased reproductive success by mating with multiple females while females did not. We also found no strong evidence that females experienced indirect fitness benefits through multiple matings. Body size was not a key predictor of male reproductive success, and for females, body condition – but not body length – was the critical fecundity trait. Altogether, a combination of factors suggests that post‐copulatory mechanisms of sexual selection (e.g. sperm competition, cryptic female choice) may play critical roles in this mating system and perhaps that of other snakes. We interpret our findings in the context of sexual conflict – a ubiquitous and potent driver of mating strategy evolution – to propose a scenario for the evolution of female promiscuity that is applicable to many other animal systems where males roam widely to locate females at high costs.

中文翻译：

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在男女交配的系统中进行性选择，体型大小和生殖成功的强度：越大越好？

在许多动物系统中，体型是关键的选择特征：雄性选择体型较大，因为它在争夺雌性的比赛中具有繁殖优势，而雄性则自然选择繁殖力。在这里，我们使用无线电遥测技术收集了大型的男女互动数据集，并通过DNA亲子关系分析来表征性选择的强度以及两个身体尺寸指标（身体长度和状况，后者是针对男性的实验性操纵）之间的联系，在粉扑加法器的人口繁殖成功鼓腹咝蝰。我们对性选择强度的多种估计通常表明，男性比女性经历了更强的性选择。然而，尽管事实证明，雄性通过与多只雌性交配而增加了繁殖成功，而雌性却没有，但贝特曼梯度在性别上并没有不同。我们也没有发现有力的证据表明雌性会通过多次交配而间接受益。体重不是雄性生殖成功的关键指标，对于雌性来说，身体状况而非体长是关键的生殖力特征。总而言之，多种因素表明，交配后的性选择机制（例如，精子竞争，隐秘的女性选择）可能在这种交配系统中或可能在其他蛇中发挥关键作用。