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.

两性在生殖角色上存在差异，故而共享表型性状往往承受着趋异的选择压力。理论预测，趋异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，却以另一性别的适合度为代价。性拮抗（sexual antagonism）现象后续可通过性别特异性基因表达的演化得以解决，从而使两性在表型层面产生分化。尽管性二态性（sexual dimorphism）极为普遍，但近期研究证据表明，拮抗遗传变异仍在众多生物的种群中持续留存。本文报道了在标准化条件下独立演化的种群中，性拮抗与遗传漂变（genetic drift）相互作用的实验数据。研究发现，小型实验黑腹果蝇（Drosophila melanogaster）种群的雌雄适合度已出现分化：部分种群表现出高雄性适合度、低雌性适合度的特征，其余种群则呈现相反的模式。种群间的这种差异格局，与生殖适合度的分化由性拮抗等位基因的遗传漂变驱动的理论预期相一致。最后，我们讨论了本研究结果对亚分化种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。