Data from: Genetic drift in antagonistic genes leads to divergence in sex-specific fitness between experimental populations of Drosophila melanogaster

Males and females differ in their reproductive roles and as a consequence are often under diverging selection pressures on shared phenotypic traits. Theory predicts that divergent selection can favor the invasion of sexually antagonistic alleles, which increase the fitness of one sex at the detriment of the other. Sexual antagonism can be subsequently resolved through the evolution of sex-specific gene expression, allowing the sexes to diverge phenotypically. While sexual dimorphism is very common, recent evidence also shows that antagonistic genetic variation continues to segregate in populations of many organisms. Here we present empirical data on the interaction between sexual antagonism and genetic drift in populations that have independently evolved under standardized conditions. We demonstrate that small experimental populations of Drosophila melanogaster have diverged in male and female fitness, with some populations showing high male, but low female fitness while other populations show the reverse pattern. The between-population patterns are consistent with the differentiation in reproductive fitness being driven by genetic drift in sexually antagonistic alleles. We discuss the implications of our results with respect to the maintenance of antagonistic variation in subdivided populations and consider the wider implications of drift in fitness-related genes.

雌雄个体在生殖角色上存在差异，因此二者在共有表型性状上往往承受着分化的选择压力。理论预测，分化选择会促进性拮抗等位基因（sexually antagonistic alleles）的入侵——这类等位基因可提升某一性别的适合度，却会对另一性别的适合度造成损害。性拮抗作用后续可通过进化出性别特异性基因表达得以缓解，使两性在表型上产生分化。尽管性二态性极为普遍，但近期研究证据显示，拮抗遗传变异仍在诸多生物的种群中持续维持遗传多态。本文呈现了标准化实验条件下独立进化的种群中，性拮抗作用与遗传漂变相互作用的实证数据。我们的实验表明，小型黑腹果蝇（Drosophila melanogaster）实验种群在雌雄适合度上已出现分化：部分种群呈现高雄性适合度、低雌性适合度的特征，其余种群则呈现相反的模式。种群间的这类差异模式，与生殖适合度的分化由性拮抗等位基因的遗传漂变所驱动的结论相一致。我们讨论了本研究结果对于亚群中拮抗变异维持的启示，并探讨了适合度相关基因中遗传漂变的更广泛影响。