Experimental evidence for the role of sexual selection in the evolution of cuticular hydrocarbons in the dung beetle, Onthophagus taurus

A role for sexual selection in the evolution of insect cuticular hydrocarbons (CHCs) is suggested by observations of selection acting on male CHCs during female mate choice. However, evidence that CHCs evolve in response to sexual selection is generally lacking, and there is a need to extend our understanding beyond well-studied taxa. Experimental evolution offers a powerful approach to investigate the effect of sexual selection on the evolution of insect CHCs. We conducted such an experiment using the dung beetle, Onthophagus taurus. After six, 12 and 21 generations of experimental evolution, we measured the CHCs of beetles from three populations subject to sexual selection and three populations within which sexual selection had been removed via enforced monogamy. We found that the male CHC profile responded to the experimental removal of sexual selection. Conversely, the CHC profile of females responded to the presence of sexual selection but not to its removal. These results show that sexual selection can be an important mechanism affecting the evolution of insect CHCs, and that male and female CHCs can evolve independently.

已有观测结果显示，雌性在配偶选择过程中会对雄性表皮碳氢化合物施加选择，这提示性选择在昆虫表皮碳氢化合物（cuticular hydrocarbons, CHCs）的演化进程中扮演了重要角色。然而，目前普遍缺乏表皮碳氢化合物响应性选择而发生演化的直接证据，且相关研究的认知范围仍需拓展至已被充分研究的类群之外。实验演化（experimental evolution）是探究性选择对昆虫表皮碳氢化合物演化影响的高效研究手段。本研究以蜣螂（*Onthophagus taurus*）为实验对象开展了相关实验。在经过6代、12代和21代的实验演化后，我们分别测定了三组受性选择作用的蜣螂种群，以及三组通过强制单配偶制消除了性选择的蜣螂种群的表皮碳氢化合物谱图。研究结果显示，雄性表皮碳氢化合物谱图会响应性选择的实验性去除；与之相反，雌性的表皮碳氢化合物谱图仅会响应性选择的存在，而非其去除过程。上述结果表明，性选择可作为影响昆虫表皮碳氢化合物演化的重要机制，且雌雄个体的表皮碳氢化合物谱图可独立演化。