Experiment 1 Behaviour - Females.dat from Interactions between the sexual identity of the nervous system and the social environment mediate lifespan in <i>Drosophila melanogaster</i>.

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，但其背后的因果机制仍未得到充分阐明。异性与同性间的社交互动在诸多生物类群中均已知会影响寿命，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区分开来，却颇具挑战。为解决这一问题，本研究对黑腹果蝇（Drosophila melanogaster）神经系统的性别属性进行了遗传操控，进而调控其性行为，并在不同社交条件下测定了果蝇的寿命。与此前研究结果一致，雌性果蝇的神经系统雄性化会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-雄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，但经雄性化处理的雌性果蝇群体则表现出类似雄性的寿命，以及类似雄性的群居生存成本。通过改变社交群体内对照组雌性与经雄性化处理雌性的混合比例，本研究发现，雄性特有的行为会对接收者产生生存成本，即便这些行为来自雌性果蝇。然而，与近期研究结果一致，本研究数据表明，求偶行为的表达带来的生存成本出乎意料地低。综上，本研究表明，神经系统介导的性别特异性行为表达本身——独立于两性间更广泛的生理差异，或接收攻击与求偶行为的经历——在介导寿命的性别差异中所起的作用较为有限。