Data from: The condition dependency of fitness in males and females: the fitness consequences of juvenile diet assessed in environments differing in key adult resources

Variation in environmental or genetic quality leads to phenotypic variation in condition, but how much variation in fitness is created by this variation in condition? Using Drosophila melanogaster, we manipulated condition via alternative larval diets and then tested several key factors predicted to influence how much variation in fitness results from differences in condition. Specifically, we were interested in whether male and female fitness are affected equally by condition and whether the strength of selection on condition depends on the abundance of key resources limiting the reproductive output of each sex. We measured selection on condition in alternative assay contexts that varied in the abundance of adult food (a key resource for females) or in the abundance of females (a key resource for males). Overall, selection tended to be stronger on males than females. However, selection on males was weakened when the abundance of their key resource (females) was elevated. Increasing the abundance of the key resource for females (live yeast) elevated their reproductive output as expected but did not change the strength of selection in this sex. Instead, this manipulation increased selection on males, suggesting that this environmental factor indirectly affects selection on males via their interaction with females.环境或遗传质量的差异会导致个体生理条件（condition）的表型变异，然而这种生理条件的差异究竟会产生多大程度的适合度（fitness）变异？本研究以黑腹果蝇（Drosophila melanogaster）为实验对象，通过更换不同幼虫饲料来操控个体的生理条件，随后检验了若干被预测会影响生理条件差异所带来的适合度变异程度的关键因素。具体而言，我们关注两个核心研究问题：其一，雌雄个体的适合度是否均受生理条件的同等影响；其二，针对生理条件的选择强度是否取决于限制各性别繁殖输出的关键资源的丰度。我们在两种不同的实验环境中测定了针对生理条件的选择强度：一种环境中改变成虫食物（雌性的关键资源）的丰度，另一种环境中改变雌性个体（雄性的关键资源）的丰度。整体而言，针对雄性的选择强度通常高于雌性。然而，当雄性的关键资源（雌性）丰度提升时，针对雄性的选择强度会被削弱。提升雌性的关键资源——鲜酵母（live yeast）的丰度，正如预期那样提高了雌性的繁殖输出，但并未改变该性别的选择强度。相反，这一操控手段提升了针对雄性的选择强度，这表明该环境因素通过雌雄个体间的相互作用，间接影响了针对雄性的选择强度。