Data from: The decline in fitness with inbreeding: evidence for negative dominance-by-dominance epistasis in Drosophila melanogaster

Genetic interactions can play an important role in the evolution of reproductive strategies. In particular, negative dominance-by-dominance epistasis for fitness can theoretically favour sex and recombination. This form of epistasis can be detected statistically because it generates nonlinearity in the relationship between fitness and inbreeding coefficient. Measures of fitness in progressively inbred lines tend to show limited evidence for epistasis. However, tests of this kind can be biased against detecting an accelerating decline due to line losses at higher inbreeding levels. We tested for dominance-by-dominance epistasis in Drosophila melanogaster by examining viability at five inbreeding levels that were generated simultaneously, avoiding the bias against detecting nonlinearity that has affected previous studies. We find an accelerating rate of fitness decline with inbreeding, indicating that dominance-by-dominance epistasis is negative on average, which should favour sex and recombination.遗传互作（genetic interactions）在繁殖策略的演化进程中可发挥关键作用。具体而言，针对适合度的显性×显性负上位性（negative dominance-by-dominance epistasis）在理论层面可推动有性生殖与基因重组的演化。该类型的上位性可通过统计学手段检测，因其会在适合度与近交系数（inbreeding coefficient）的关联中引入非线性特征。对逐步近交品系的适合度测定结果，往往仅能提供有限的上位性检测证据。然而，此类检测方法易存在偏倚：在较高近交水平下，品系消亡会导致无法准确检测到适合度的加速下降趋势。我们以黑腹果蝇（Drosophila melanogaster）为研究对象，通过同时构建5个不同近交水平的品系并检测其生活力，规避了此前研究中干扰非线性特征检测的偏倚问题。研究发现，随着近交程度提升，适合度下降速率呈加速态势，这表明显性×显性上位性整体呈负向效应，理应会促进有性生殖与基因重组的演化。