The complexity of mating decisions in stalk-eyed flies

All too often, studies of sexual selection focus exclusively on the responses in one sex, on single traits, typically those that are exaggerated and strongly sexually dimorphic. They ignore a range of less obvious traits and behavior, in both sexes, involved in the interactions leading to mate choice. To remedy this imbalance, we analyze a textbook example of sexual selection in the stalk-eyed fly (Diasemopsis meigenii). We studied several traits in a novel, insightful, and efficient experimental design, examining 2,400 male–female pairs in a “round-robin” array, where each female was tested against multiple males and vice versa. In D. meigenii, females exhibit strong mate preference for males with highly exaggerated eyespan, and so we deliberately constrained variation in male eyespan to reveal the importance of other traits. Males performing more precopulatory behavior were more likely to attempt to mate with females and be accepted by them. However, behavior was not a necessary part ...

当前性选择领域的研究往往仅聚焦于单一性别的反应与单一性状——通常是那些高度夸张且雌雄异型特征显著的性状。此类研究往往忽略了两性中参与配偶选择互动过程的诸多不甚显著的性状与行为。为修正这一研究失衡，我们以柄眼蝇（stalk-eyed fly, *Diasemopsis meigenii*）的教科书式性选择范例为研究对象。我们采用新颖、精妙且高效的实验设计，对2400对雌雄个体开展了"循环互测"阵列式实验：每只雌性可与多只雄性进行交配测试，反之亦然。在该种柄眼蝇中，雌性对眼柄高度夸张的雄性具有显著的配偶偏好，因此我们刻意控制了雄性眼柄的变异水平，以凸显其他性状在配偶选择中的重要性。交配前行为频次更高的雄性，不仅更倾向于向雌性发起交配尝试，也更易获得雌性的接受。然而，交配前行为并非雄性成功获得交配机会的必要条件……