Data from: Insect mating signal and mate preference phenotypes covary among host plant genotypes

Sexual selection acting on small initial differences in mating signals and mate preferences can enhance signal-preference co-divergence and reproductive isolation during speciation. However, the origin of initial differences in sexual traits remains unclear. We asked whether biotic environments, a source of variation in sexual traits, may provide a general solution to this problem. Specifically, we asked whether genetic variation in biotic environments provided by host plants can result in signal-preference phenotypic covariance in a host-specific, plant-feeding insect. We used a member of the Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae) to assess patterns of variation in male mating signals and female mate preferences induced by genetic variation in host plants. We employed a novel implementation of a quantitative genetics method, rearing field-collected treehoppers on a sample of naturally-occurring replicated host plant clone lines. We found remarkably high signal-preference covariance among host plant genotypes. Thus, genetic variation in biotic environments influences the sexual phenotypes of organisms living on those environment in a way that promotes assortative mating among environments. This consequence arises from conditions likely to be common in nature (phenotypic plasticity and variation in biotic environments). It therefore offers a general answer to how divergent sexual selection may begin.

在物种形成过程中，作用于交配信号与配偶偏好初始微小差异的性选择，能够强化信号-偏好共趋异与生殖隔离。然而，性征初始差异的起源仍未明确。我们旨在探究：作为性征变异来源的生物环境，或许能为该问题提供普适性解答。具体而言，我们探究在寄主专一性植食性昆虫中，寄主植物所提供的生物环境的遗传变异，是否会引发信号-偏好表型协方差。我们以半翅目（Hemiptera）角蝉科（Membracidae）双斑恩蝉（Enchenopa binotata）物种复合体中的一个类群为研究对象，评估寄主植物遗传变异所诱导的雄性交配信号与雌性配偶偏好的变异模式。我们采用了定量遗传学方法的全新实施范式，将野外采集的角蝉饲养于一组天然重复的寄主植物无性系中。我们发现，不同寄主植物基因型间的信号-偏好表型协方差极高。由此可见，生物环境的遗传变异会影响栖息于该环境中的生物的性表型，进而促进不同环境间的选型交配。该结果源于自然界中普遍存在的条件：表型可塑性（phenotypic plasticity）与生物环境变异。因此，本研究为趋异性选择的起始机制提供了普适性解答。