Supplementary Material 9 - Code from Heightened condition dependence of the sexual transcriptome as a function of genetic quality in <i>Drosophila melanogaster</i> head tissue

Theory suggests sexual traits should show heightened condition dependent expression. This prediction has been tested extensively in experiments where condition has been manipulated through environmental quality. Condition dependence as a function of genetic quality has, however, only rarely been addressed, despite its central importance in evolutionary theory. To address the effect of genetic quality on expression of sexual and non-sexual traits, we here compare gene expression in <i>Drosophila melanogaster</i> head tissue between flies with intact genomes (high condition) and flies carrying a major deleterious mutation (low condition). We find that sex-biased genes show heightened condition dependent expression in both sexes, and that expression in low condition males and females regresses towards a more similar expression profile. As predicted, sex-biased expression was more sensitive to condition in males compared to females, but surprisingly female-biased, rather than male-biased, genes show the higher sensitivity to condition in both sexes. Our results thus support the fundamental predictions of the theory of condition dependence when condition is a function of genetic quality.演化理论指出，性征的表达应具有更高的条件依赖性。该预测已在诸多通过调控环境质量以改变个体条件的实验中得到广泛验证。然而，尽管条件依赖性在演化理论中占据核心地位，但以遗传质量为决定因素的条件依赖性却鲜有研究。为探究遗传质量对性征与非性征基因表达的影响，本研究对黑腹果蝇（*Drosophila melanogaster*）头部组织的基因表达进行了比较：一组为基因组完整的个体（条件优良组），另一组为携带主要有害突变的个体（条件劣化组）。我们发现，两性中的性别偏向基因均表现出更强的条件依赖性表达；且条件劣化的雌雄个体，其基因表达谱会趋于更为相似。正如预测那般，相较于雌性，雄性的性别偏向表达对条件变化更为敏感；但令人意外的是，在两性中，对条件变化敏感度更高的均为雌性偏向基因，而非雄性偏向基因。因此，当个体条件由遗传质量决定时，本研究结果支持条件依赖性理论的核心预测。