Data from: Sexual dimorphism in epicuticular compounds despite similar sexual selection in sex role reversed seed beetles

Sexual selection imposed by mating preferences is often implicated in the evolution of both sexual dimorphism and divergence between species in signalling traits. Epicuticular compounds (ECs) are important signalling traits in insects and show extensive variability among and within taxa. Here we investigate whether variation in the multivariate EC profiles of two sex role reversed beetle species, Megabruchidius dorsalis and M. tonkineus, predicts mate attractiveness and mating success in males and females. The two species had highly distinct EC profiles and both showed significant sexual dimorphism in ECs. Age and mating status in both species were also distinguishable by EC profile. Males and females of both species showed significant association between their EC profile and attractiveness, measured both as latency to mating and as success in mate-choice trials. Remarkably, the major multivariate vector describing attractiveness was correlated in both species, both sexes, and in both choice and no-choice experiments such that increased attractiveness was in all cases associated with a similar multivariate modification of EC composition. Furthermore, in both sexes this vector of attractiveness was associated with more male-like EC profiles, as well as those characterising younger and non-virgin individuals, which might reflect a general preference for individuals of high condition in both sexes. Despite significant sexual selection on EC composition, however, we found no support for the proposition that sexual selection is responsible for divergence in ECs between these species.

由交配偏好所介导的性选择，常与性二型性的演化以及物种间信号性状的分化紧密相关。表皮碳氢化合物（Epicuticular compounds, ECs）是昆虫重要的信号性状，在不同类群及类群内部均存在广泛的变异。本研究以两种性角色反转的甲虫——背大豆象（Megabruchidius dorsalis）和东京大豆象（M. tonkineus）为研究对象，旨在探究其多变量EC谱的差异能否预测雌雄个体的配偶吸引力与交配成功率。
两个物种的EC谱差异显著，且二者的EC谱均存在显著的性二型性。此外，两个物种的个体年龄与交配状态也可通过EC谱进行区分。
两个物种的雌雄个体，其EC谱与吸引力（通过交配潜伏期与配偶选择试验中的交配成功率衡量）均存在显著关联。值得注意的是，表征吸引力的核心多变量向量在两个物种、雌雄两性，以及选择试验与无选择试验中均呈显著相关：无论何种情境下，吸引力提升均与EC组成的相似多变量改变相关联。
此外，在两性中，该吸引力相关向量均与更具雄性特征的EC谱，以及表征年轻、非初交个体的EC谱相关联，这或许反映了两性均普遍偏好生理状态更佳的优质个体。
尽管EC组成受到了显著的性选择作用，但本研究并未发现证据支持“性选择是导致这两个物种EC谱分化的原因”这一假说。