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.

雄性与雌性在生殖角色上存在显著差异，因此二者在共有表型性状上往往承受着趋异的选择压力。理论预测，趋异选择会推动性拮抗等位基因（sexually antagonistic alleles）的入侵——这类等位基因可提升某一性别的适合度，却对另一性别的适合度产生损害。性拮抗作用后续可通过性别特异性基因表达的演化得到缓解，进而使两性在表型上产生分化。尽管性二态现象极为普遍，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保有分离多态性。本研究呈现了在标准化培养条件下独立演化的种群中，性拮抗作用与遗传漂变之间相互作用的实验数据。研究结果表明，小型黑腹果蝇（Drosophila melanogaster）实验种群的雌雄适合度已发生明显分化：部分种群呈现高雄性适合度、低雌性适合度的特征，而其余种群则表现出相反的模式。种群间的这种分化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机制相一致。本研究讨论了研究结果对亚种群中拮抗遗传变异维持机制的启示，并探讨了适合度相关基因中遗传漂变的更广泛学术意义。