The evolutionary trajectory of drosophilid walking

Neural circuits must both execute the behavioral repertoire of individuals and account for behavioral variation across species. Understanding how this variation emerges over evolutionary time requires large-scale phylogenetic comparisons of behavioral repertoires. Here, we describe the evolution of walking in fruit flies by capturing high-resolution, unconstrained movement from 13 species and 15 strains of drosophilids. We find that walking can be captured in a universal behavior space, the structure of which is evolutionarily conserved. However, the occurrence of, and transitions between, specific movements have evolved rapidly, resulting in repeated convergent evolution in the temporal structure of locomotion. Moreover, a meta-analysis demonstrates that many behaviors evolve more rapidly than other traits. Thus, the architecture and physiology of locomotor circuits can both execute precise individual movements in one species and simultaneously support rapid evolutionary changes in the...神经环路（Neural circuits）既要介导个体完整的行为谱（behavioral repertoire）表达，又要解释跨物种的行为差异。要阐明这类差异如何在进化历程中逐步形成，需对行为谱开展大规模的系统发育（phylogenetic）比较研究。本研究通过记录13个物种、15个果蝇科（Drosophilidae）品系的高分辨率无约束运动轨迹，系统阐释了果蝇行走行为的演化历程。我们发现，行走行为可被纳入一个普适性行为空间中，该空间的结构在进化层面具有高度保守性。然而，特定运动模式的出现以及运动模式间的转换却演化迅速，最终导致运动时序结构出现多次趋同演化（Convergent evolution）。此外，一项荟萃分析（meta-analysis）表明，诸多行为的演化速率显著快于其他性状（trait）。由此可见，运动环路（locomotor circuits）的结构与生理机能，既能在单一物种中实现精准的个体运动，又可同时支持运动行为快速的演化改变……