Data from: Aggressive behaviours, food deprivation and the foraging gene

A pleiotropic gene governs multiple traits, which might constrain the evolution of complexity due to conflicting selection on these traits. However, if the pleiotropic effect is modular, then this can facilitate synergistic responses to selection on functionally related traits, thereby leveraging the evolution of complexity. To understand the evolutionary consequence of pleiotropy, the relation among functionally different traits governed by the same gene is key. We examined a pleiotropic function of the foraging (for) gene with its rover and sitter allelic variants in fruit fly, Drosophila melanogaster. We measured for's effect on adult male aggressive behaviours and whether this effect was shaped by for's known role in food-related traits. Rover exhibited higher levels of offensive behaviour than sitters and s2, a sitter-like mutant on rover genetic background. With a Markov chain model, we estimated the rate of aggression escalation, and found that the rover pattern of aggressive escalation more rapidly intensified fights. Subsequent analysis revealed that this was not caused by for's effect on food-related traits, suggesting that for might directly regulate aggressive behaviours. Food deprivation did not elevate aggression, but reduced intermediate-level aggressive behaviours. Aggression and other foraging-related behaviour might comprise a synergistic trait module underlaid by this pleiotropic gene.

多效基因（pleiotropic gene）可调控多个性状，由于这些性状存在相互冲突的选择压力，其可能会限制复杂性的演化。然而，若多效效应具备模块化特征，则可促进功能相关性状在选择作用下产生协同响应，进而推动复杂性的演化。为阐明多效性的演化后果，解析同一基因所调控的不同功能性状间的关联是核心关键。本研究以黑腹果蝇（Drosophila melanogaster）中的觅食基因（foraging (for)）为研究对象，考察了其漫游者型（rover）与逗留者型（sitter）等位变异所介导的多效性功能。我们检测了该基因对成年雄性攻击行为的调控效应，并探究该效应是否由for基因在食物相关性状中的已知功能所介导。相较于逗留者型果蝇，以及遗传背景为漫游者型的类逗留者突变体s2，漫游者型果蝇的攻击行为发起水平更高。我们借助马尔可夫链模型（Markov chain model）估算了攻击升级速率，结果发现漫游者型的攻击升级模式可更快推动争斗升级。后续分析表明，该效应并非由for基因对食物相关性状的调控所引发，这表明for基因可能直接参与攻击行为的调控。食物剥夺并未提升攻击行为水平，但会降低中等强度攻击行为的发生比例。攻击行为与其他觅食相关行为或可共同构成一个受该多效基因调控的协同性状模块。