Data from: Structural biomechanics determine spectral purity of bush-cricket calls

Bush-crickets (Orthoptera: Tettigoniidae) generate sound using tegminal stridulation. Signalling effectiveness is affected by the widely varying acoustic parameters of temporal pattern, frequency and spectral purity (tonality). During stridulation, frequency multiplication occurs as a scraper on one wing scrapes across a file of sclerotized teeth on the other. The frequency with which these tooth–scraper interactions occur, along with radiating wing cell resonant properties, dictates both frequency and tonality in the call. Bush-cricket species produce calls ranging from resonant, tonal calls through to non-resonant, broadband signals. The differences are believed to result from differences in file tooth arrangement and wing radiators, but a systematic test of the structural causes of broadband or tonal calls is lacking. Using phylogenetically controlled structural equation models, we show that parameters of file tooth density and file length are the best-fitting predictors of tonality across 40 bush-cricket species. Features of file morphology constrain the production of spectrally pure signals, but systematic distribution of teeth alone does not explain pure-tone sound production in this family.螽斯（Bush-cricket，直翅目Orthoptera：螽斯科Tettigoniidae）通过覆翅摩擦发声（tegminal stridulation）产生鸣声。其鸣唱信号的传讯效能受时间模式、频率与频谱纯度（音调纯正度，tonality）等差异显著的声学参数影响。在摩擦发声过程中，一侧翅上的刮器（scraper）划过另一侧翅上排列有硬化齿（sclerotized teeth）的音锉（file）时，会产生频率倍增现象。这些齿-刮器相互作用的发生频率，连同辐射翅室的共振特性，共同决定了鸣唱声的频率与音调纯正度。不同螽斯物种的鸣唱声范围涵盖共振型纯音鸣唱至非共振型宽带信号。学界认为这类差异源于音锉齿排列与翅辐射结构的不同，但目前仍缺乏针对宽带或纯音鸣唱结构成因的系统性检验。本研究采用系统发育控制结构方程模型（phylogenetically controlled structural equation models），对40个螽斯物种展开分析，结果显示音锉齿密度与音锉长度参数是音调纯正度的最优预测因子。翅形态特征制约着频谱纯信号的产生，但仅靠牙齿的系统性分布无法解释该类群的纯音鸣声产生机制。