Data from: Experimental sexual selection and sex comb evolution in Drosophila

Sexual selection can drive rapid evolutionary change in reproductive behaviour, morphology and physiology. This often leads to the evolution of sexual dimorphism, and continued exaggerated expression of dimorphic sexual characteristics, although a variety of other alternative selection scenarios exist. Here, we examined the evolutionary significance of a rapidly evolving, sexually dimorphic trait, sex comb tooth number, in two Drosophila species. The presence of the sex comb in both D. melanogaster and D. pseudoobscura is known to be positively related to mating success, although little is yet known about the sexually selected benefits of sex comb structure. In this study, we used experimental evolution to test the idea that enhancing or eliminating sexual selection would lead to variation in sex comb tooth number. However, the results showed no effect of either enforced monogamy or elevated promiscuity on this trait. We discuss several hypotheses to explain the lack of divergence, focussing on sexually antagonistic coevolution, stabilizing selection via species recognition and nonlinear selection. We discuss how these are important, but relatively ignored, alternatives in understanding the evolution of rapidly evolving sexually dimorphic traits.性选择（Sexual selection）可驱动生殖行为、形态及生理学层面的快速进化改变，这通常会促成性二态性（sexual dimorphism）的演化，并使二态性性特征持续呈现夸张表达，尽管目前已存在多种其他替代性选择情景。本研究以两种果蝇属（Drosophila）物种为对象，探究其中一个快速演化的性二态性状——性梳（Sex comb）齿数的进化意义。已知黑腹果蝇（D. melanogaster）与拟暗果蝇（D. pseudoobscura）的性梳存在与否与交配成功率呈正相关，但目前学界对性梳结构所带来的性选择益处仍了解有限。本研究借助实验进化（experimental evolution）手段，验证“增强或消除性选择会导致性梳齿数产生变异”这一假说。然而实验结果显示，无论是强制单配偶制（enforced monogamy）还是提升多配偶程度，均未对该性状产生显著影响。本文探讨了多种用以解释该未出现分化现象的假说，重点聚焦于性拮抗协同进化（sexually antagonistic coevolution）、基于物种识别的稳定选择（stabilizing selection）以及非线性选择（nonlinear selection）。本文还阐述了这些机制在解析快速演化的性二态性状进化过程中的重要价值——尽管它们在该研究领域中相对被忽视。