Data from: Sexual selection and experimental evolution of chemical signals in Drosophila pseudoobscura

Our expectations for the evolution of chemical signals in response to sexual selection are uncertain. How are chemical signals elaborated? Does sexual selection result in complexity of the composition or in altered quantities of expression? We addressed this in Drosophila pseudoobscura by examining male and female cuticular hydrocarbons (CHs) after 82 generations of elevated (E) sexual selection or relaxed sexual selection through monogamy (M). The CH profile consisted of 18 different components. We extracted three eigenvectors using principal component analysis that explained 72% of the variation. PC1 described the amount of CHs produced, PC2 the trade-off between short- and long-chain CHs and PC3 the trade-off between apparently arbitrary CHs. In both sexes, the amount of CHs produced was greater in flies from the E treatment. PC3 was also higher, indicating that sexual selection also influenced the evolution of CH composition. The sexes differed in all three PCs indicating substantial sexual dimorphism in this species, although the magnitude of this dimorphism was not increased as a result of our experimental evolution. Collectively, our work provides direct evidence that sexual selection plays an important role in the evolution of CHs in D. pseudoobscura, and that both increased quantity and overall composition are targeted.我们对于性选择驱动下化学信号演化的预期尚不明确。化学信号究竟是如何被精细化修饰的？性选择究竟会导致信号组分复杂度提升，还是仅改变其表达量？本研究以拟暗果蝇（Drosophila pseudoobscura）为对象，在经过82代强化性选择（E）或通过单配偶制实现的松弛性选择（M）后，对其雌雄个体的表皮碳氢化合物（cuticular hydrocarbons, CHs）展开了检测分析，以解答上述问题。该表皮碳氢化合物谱共包含18种不同组分。我们通过主成分分析（principal component analysis, PCA）提取了3个特征向量，累计可解释72%的总变异量。其中主成分1（PC1）反映了个体所产生的表皮碳氢化合物总量，主成分2（PC2）体现了短链与长链表皮碳氢化合物之间的权衡关系，主成分3（PC3）则对应了看似无关联的表皮碳氢化合物之间的权衡。在雌雄个体中，经E组处理的果蝇所产生的表皮碳氢化合物总量均更高；同时其PC3得分也更高，表明性选择同样会对表皮碳氢化合物的组分演化产生影响。雌雄个体在三个主成分上均存在显著差异，说明该物种存在明显的性二态性；不过本次实验演化并未使该性二态性的程度得到提升。综上，本研究为性选择在拟暗果蝇表皮碳氢化合物演化中发挥重要作用提供了直接证据，同时证实性选择同时靶向调控表皮碳氢化合物的表达量提升与整体组分优化。