Experiment 2 Survival.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in Drosophila melanogaster

Sex differences in lifespan are ubiquitous, but the underlying causal factors remain poorly understood. Inter- and intrasexual social interactions are well known to influence lifespan in many taxa, but it has proved challenging to separate the role of sex-specific behaviours from wider physiological differences between the sexes. To address this problem, we genetically manipulated the sexual identity of the nervous system—and hence sexual behaviour—in Drosophila melanogaster, and measured lifespan under varying social conditions. Consistent with previous studies, masculinization of the nervous system in females induced male-specific courtship behaviour and aggression, while nervous system feminization in males induced male–male courtship and reduced aggression. Control females outlived males, but masculinized female groups displayed male-like lifespans and male-like costs of group living. By varying the mixture of control and masculinized females within social groups, we show that male-specific behaviours are costly to recipients, even when received from females. However, consistent with recent findings, our data suggest the courtship expression to be surprisingly low cost. Overall, our study indicates that nervous system-mediated expression of sex-specific behaviour per se—independent of wider physiological differences between the sexes, or the receipt of aggression or courtship—plays a limited role in mediating sex differences in lifespan.寿命的性别差异普遍存在，但背后的核心因果机制仍尚未被充分阐明。异性间与同性间的社交互动已被证实会影响诸多生物类群的寿命，但要将性别特异性行为的作用与两性间更广泛的生理差异剥离开来，却始终颇具挑战。为解决这一研究难题，我们对黑腹果蝇（Drosophila melanogaster）神经系统的性别属性进行了遗传操控，以此调控其性行为表现，并在多种社交条件下测定了果蝇的寿命。与既往研究结果一致，雌性果蝇的神经系统雄性化可诱导出雄性特有的求偶行为与攻击行为；而雄性果蝇的神经系统雌性化，则会引发雄性个体间的求偶行为并降低攻击水平。对照组雌性果蝇的寿命长于雄性，但神经系统雄性化的雌性群体则呈现出类似雄性的寿命特征，以及与雄性相似的群居生存代价。通过调整社交群体中对照组雌性与雄性化雌性的组成比例，我们证实雄性特异性行为会对接收者造成生存代价，即便该行为来自雌性个体。不过，与近期相关研究结论相符的是，我们的数据显示求偶行为的生存代价出人意料地低廉。总体而言，本研究表明，仅由神经系统介导的性别特异性行为表达——独立于两性间更广泛的生理差异，或是接收攻击与求偶行为的影响——在介导寿命性别差异的过程中所发挥的作用相对有限。