Data from: How grasshoppers respond to road noise: developmental plasticity and population differentiation in acoustic signalling

1. Increasing levels of anthropogenic noise have the potential to mask signals of acoustically communicating species in their natural habitats. Animals in noise-polluted habitats typically adjust their signals away from high background noise levels to ensure successful signal transmission under challenging environmental conditions. Earlier we demonstrated that male Chorthippus biguttulus grasshoppers from roadside habitats produce courtship signals with elevated frequency components compared to conspecifics from non-roadside habitats. 2. Here we use a common garden approach to study the mechanisms underlying this response. We transferred grasshopper nymphs from seven roadside as well as five non-roadside habitats to the laboratory to rear half of them under noisy and the other half under quiet conditions in a full factorial two-by-two design. Courtship songs of adult males were later recorded under standardized quiet conditions. 3. Males exposed to road noise as nymphs produced signals with higher frequency components compared to males reared under quiet conditions, indicating developmental plasticity as a mechanism underlying the signal adjustment to anthropogenic noise in grasshoppers. 4. In addition, males originating from roadside habitats produced signals with higher frequency components and an increased syllable to pause ratio - a sexually selected signal trait - compared to males from non-roadside habitats. 5. Our results demonstrate for the first time that developmental plasticity may play an important role in song trait modifications in response to anthropogenic noise. Furthermore they suggest that multiple roadside populations may have diverged in parallel, possibly in response to selection for minimizing signal masking by road noise.

1. 日益加剧的人为噪声（anthropogenic noise）有可能掩盖自然生境中以声学信号进行交流的物种的通讯信号。处于噪声污染生境中的动物通常会调整其信号，避开高背景噪声频段，以确保在严苛环境下信号仍能成功传递。此前我们已证实，相较于来自非路边生境的同种个体，路边生境的雄性大翅雏蝗（Chorthippus biguttulus）会发出频率成分更高的求偶信号。
2. 本研究采用共同花园实验（common garden approach）来探究这一响应背后的机制。我们从7处路边生境与5处非路边生境采集了蝗蝻，并采用完全双因子析因设计（full factorial two-by-two design），将其中一半置于噪声环境、另一半置于安静环境中于实验室饲养。后续在标准化安静条件下记录了成年雄性的求偶鸣声。
3. 相较于在安静环境中饲养的雄性个体，若蝗蝻阶段暴露于道路噪声，则成年后发出的信号频率成分更高，这表明发育可塑性（developmental plasticity）是蝗虫针对人为噪声调整信号的潜在机制。
4. 此外，与来自非路边生境的雄性相比，源自路边生境的雄性发出的信号频率成分更高，且音节-停顿比（syllable to pause ratio）——这一经过性选择的信号性状——也有所提升。
5. 本研究首次证实，发育可塑性在人为噪声诱导的鸣声性状改变中发挥了重要作用。此外，研究结果还表明，多个路边种群可能发生了平行分化，这或许是为了适应选择压力，以最小化道路噪声对信号的掩盖效应。