Stay tuned: active amplification tunes tree-cricket ears to track temperature-dependent song frequency

Tree cricket males produce tonal songs, used for mate attraction and male–male interactions. Active mechanics tunes hearing to conspecific song frequency. However, tree cricket song frequency increases with temperature, presenting a problem for tuned listeners. We show that the actively amplified frequency increases with temperature, thus shifting mechanical and neuronal auditory tuning to maintain a match with conspecific song frequency. Active auditory processes are known from several taxa, but their adaptive function has rarely been demonstrated. We show that tree crickets harness active processes to ensure that auditory tuning remains matched to conspecific song frequency, despite changing environmental conditions and signal characteristics. Adaptive tuning allows tree crickets to selectively detect potential mates or rivals over large distances and is likely to bestow a strong selective advantage by reducing mate-finding effort and facilitating intermale interactions.

树蟋（Tree cricket）雄虫会发出音调性鸣曲，此类鸣曲用于求偶吸引以及雄虫间的交互行为。其主动听觉力学机制可将听觉系统调谐至同种鸣曲的频率。然而，树蟋的鸣曲频率会随环境温度升高而上升，这给已完成听觉调谐的个体带来了适配难题。本研究证实，主动放大的听觉响应频率同样会随温度升高而上升，由此改变听觉的力学与神经元调谐特性，从而维持与同种鸣曲频率的匹配。目前已在多个分类类群（taxa）中发现主动听觉过程，但这类过程的适应性功能极少得到证实。本研究表明，树蟋可借助主动听觉过程，在环境条件与信号特征发生变化时，仍能维持听觉调谐与同种鸣曲频率的匹配性。这种适应性调谐使得树蟋能够在远距离范围内选择性地识别潜在配偶或竞争对手，并通过降低求偶成本、促进雄虫间的交互行为，从而赋予其显著的选择优势。