Data from: Territory defense as a condition-dependent component of male reproductive success in Drosophila serrata

Sexual selection arises from both intrasexual competition and mate choice. With respect to the evolution of male traits, there is a vast literature documenting the existence of female choice and male-male competition, and both have been shown to co-occur in many species. Despite numerous studies of these two components of male reproductive success in isolation, few have investigated whether and how they interact to determine total sexual selection. To address this, we investigate male territoriality in Drosophila serrata, a species in which female preference for male sexual pheromones (cuticular hydrocarbons or CHCs) have been extensively studied. We demonstrate that territoriality occurs, that it involves direct male-male aggressive interactions, and that it contributes to variation in male mating success. Results from a phenotypic manipulation also indicate that territorial success is condition-dependent, although a genetic manipulation of condition, involving three generations of full-sib inbreeding, failed to find a significant effect. Finally, selection assays also suggest that territorial success depends on male body size but not on CHCs, whereas the opposite is true for mating success.

性选择（Sexual selection）源于同性竞争（intrasexual competition）与配偶选择（mate choice）两大途径。针对雄性性状（male traits）的演化，已有大量文献证实雌性选择（female choice）与雄性间竞争（male-male competition）的存在，且二者在诸多物种中均呈共存状态。尽管已有众多研究单独剖析雄性繁殖成功（male reproductive success）的这两个影响因子，但鲜有研究探讨二者是否会以及如何通过交互作用共同决定整体性选择的强度。为填补这一研究空白，本研究以Serrata果蝇（Drosophila serrata）为研究对象——该物种中雌性对雄性性信息素——表皮碳氢化合物（cuticular hydrocarbons，简称CHCs）——的偏好已被广泛研究。本研究证实该物种存在雄性领地行为（male territoriality），该行为涉及雄性间直接的攻击性互动，且会对雄性交配成功率（mating success）的变异产生影响。表型操控（phenotypic manipulation）实验结果同样表明，领地获得成功率存在条件依赖性（condition-dependent）；然而一项通过三代全同胞近交（full-sib inbreeding）实现的条件遗传操控实验，并未检测到显著的关联效应。最后，选择实验（selection assays）结果显示，领地获得成功率仅与雄性体型大小（male body size）相关，而与CHCs无关；但交配成功率的关联模式恰好相反。