Producing calls with increased minimum carrier frequency is well documented in sound communicating species confronted with noise pollution, possibly helping them to avoid acoustic masking of low-frequency signals. However, the lack of studies on invertebrates limits our understanding of the potentially adverse effects of anthropogenic noise on natural populations. While males of the grasshopper Chorthippus biguttulus are known to produce courtship signals with elevated low-frequency local maxima (LFLM) in roadside populations, previous studies provided no insight into morphological traits underlying LFLM shifts. Although developmental plasticity was identified as one main factor accounting for elevated LFLM, an additional role for a more hard-wired trait architecture was proposed, possibly as a result of adaptation to traffic noise. Our current study therefore aims to assess (1) whether the position of LFLM is related to male body size, (2) whether body size is correlated with motorway age, and (3) whether the position of LFLM is correlated with motorway age in C. biguttulus males from roadside populations. In addition to substantial variation in LFLM among C. biguttulus males, we found that larger males produced signals with lower LFLM, suggesting a potential role in female choice as a predictor of male quality. While we found no significant correlation between LFLM and motorway age, C. biguttulus males were larger near older motorway sections. This positive correlation may be due to several reasons, including: (1) higher nutrient concentration and availability in plant tissues due to eutrophication of roadside habitats; (2) temporal succession of male size phenotypes during colonization processes; and/or (3) selection for larger body size in roadside populations. Our results highlight the multifaceted and often complex nature of the relationships between morphology, signal traits and anthropogenic pressures on sound communication in invertebrates.

中文翻译：

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在路边种群的雄性蚱蜢中，高速公路年龄与较大的体型有关，但与歌曲载波频率无关

在面临噪声污染的声音通信物种中，以增加的最小载波频率产生呼叫是有据可查的，这可能有助于它们避免低频信号的声学掩蔽。然而，缺乏对无脊椎动物的研究限制了我们对人为噪声对自然种群的潜在不利影响的理解。虽然已知蚱蜢 Chorthippus biguttulus 的雄性会在路边种群中产生具有升高的低频局部最大值 (LFLM) 的求偶信号，但之前的研究并未提供对 LFLM 变化背后的形态特征的洞察。尽管发育可塑性被确定为导致 LFLM 升高的一个主要因素，但提出了更硬连接的特征结构的额外作用，这可能是适应交通噪音的结果。因此，我们目前的研究旨在评估 (1) LFLM 的位置是否与男性体型相关，(2) 体型是否与高速公路年龄相关，以及 (3) LFLM 的位置是否与 C 中的高速公路年龄相关. 来自路边种群的 biguttulus 雄性。除了在 C. biguttulus 雄性中 LFLM 的显着变化之外，我们发现较大的雄性产生具有较低 LFLM 的信号，这表明在雌性选择中作为雄性品质的预测指标的潜在作用。虽然我们发现 LFLM 与高速公路年龄之间没有显着相关性，但在较老的高速公路路段附近，C. biguttulus 雄性更大。这种正相关可能是由于几个原因，包括：(1) 由于路边栖息地的富营养化，植物组织中的养分浓度和可用性较高；(2) 定植过程中雄性体型表型的时间连续性；和/或 (3) 在路边人群中选择更大的体型。我们的研究结果强调了无脊椎动物的形态、信号特征和人为压力对无脊椎动物声音交流之间关系的多方面且通常是复杂的性质。