Data from: Divergent artificial selection for female reproductive investment has a sexually concordant effect on male reproductive success

Depending on the genetic architecture of male and female fitness, sex-specific selection can have negative, positive or neutral consequences for the opposite sex. Theory predicts that conflict between male and female function may drive the breakdown of intrasexual genetic correlations, allowing sexual dimorphism in sexually antagonistic traits. Reproductive traits are the epitome of this, showing highly differentiated proximate functions between the sexes. Here we use divergent artificial selection lines for female reproductive investment to test how female-specific selection on a sex-limited trait affects male reproductive success in a precocial bird, the Japanese quail (Coturnix japonica). We demonstrate that selection for increased egg investment in females positively affects male reproductive success both in competitive and non-competitive mating situations. This increased reproductive success was linked to a relatively larger left testis in males originating from lines selected for high female reproductive investment. Given that female quail have functional gonads only on their left side, this correlated response indicates that selection has acted on the shared developmental basis of male and female gonads. Our study thereby provides evidence for a positive genetic correlation between key reproductive traits in males and females despite a high degree of sexual dimorphism, and suggests that, in this system, selection on reproductive function is sexually concordant.依据雌雄适合度的遗传架构，性别特异性选择 (sex-specific selection) 对异性可产生负面、正面或中性的影响。理论预测，雌雄功能间的冲突可能打破同性内遗传相关 (intrasexual genetic correlations)，进而促使性拮抗性状 (sexually antagonistic traits) 演化出雌雄二态性 (sexual dimorphism)。生殖性状正是此类现象的典型代表，其在雌雄个体间的近因功能 (proximate functions) 呈现高度分化。本研究以早成鸟 (precocial bird) 日本鹌鹑 (Coturnix japonica) 为研究材料，采用针对雌性生殖投入 (female reproductive investment) 的双向人工选择品系 (divergent artificial selection lines)，探究限性性状 (sex-limited trait) 上的雌性特异性选择如何影响雄性生殖成功率 (male reproductive success)。研究结果显示，针对雌性卵子投入的选择，无论在竞争性还是非竞争性交配情境中，均能对雄性生殖成功率产生正向影响。该雄性生殖成功率的提升，与来自高雌性生殖投入选择品系的雄性个体拥有相对更大的左侧睾丸存在关联。鉴于雌性鹌鹑仅左侧具有功能性性腺 (gonads)，这一相关响应 (correlated response) 表明选择作用于雌雄性腺的共同发育基础。本研究由此证实，尽管雌雄生殖性状存在高度的雌雄二态性，但二者间仍存在正向遗传相关 (genetic correlation)；同时表明，在该研究体系中，针对生殖功能的选择为性协同选择 (sexually concordant)。