Optimal mate choice based on the assessment of communication signals can be constrained by multiple sources of noise. One well-known impediment to acoustically guided mating decisions is the ambient noise created by multiple signaling individuals in large social groups, in which ambient noise can mask signals by impairing signal recognition and discrimination by receivers. Although studied far less often, another potential source of noise in communication systems stems from variability or inconsistency in how signalers produce their signals. Consistency is especially important in the context of mate choice because sexual advertisement signals are frequently produced repeatedly through time and are composed of constituent parts (e.g., notes and pulses) that are repeated within signals. Inconsistent signal production within individuals has the potential to mask between-individual differences that are often the target of receiver decision-making. In this study of Cope’s gray treefrog, Hyla chrysoscelis, we tested the hypothesis that ambient noise and inconsistent signaling, both independently and synergistically, impair discrimination of species identity. We assayed female discrimination based on pulse rate, a signal of species identity, in quiet and at three levels of ambient noise designed to simulate a breeding chorus. We used synthetic advertisement calls that were invariant or generated with one of three experimental levels of inconsistency in pulse rate, chosen based on levels of within-individual variation observed in natural calls. Pulse rate discrimination was impaired by average and above-average levels of chorus noise, but not by inconsistency in signal production. Receivers spent slightly more time making decisions at the highest level of chorus noise, but response latencies were unaffected by inconsistency. There was no evidence of synergism between ambient noise and inconsistency. Our results suggest that ambient noise, but not inconsistency in signal production, may limit sexual selection on a signal of species identity in natural settings.

中文翻译：

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在 Cope 的灰色树蛙（Hyla chrysoscelis）中，物种识别受到合唱噪声的限制，但信号产生的不一致不受限制

基于通信信号评估的最佳配对选择可能受到多种噪声源的限制。声学引导交配决策的一个众所周知的障碍是由大型社会群体中的多个信号个体产生的环境噪声，其中环境噪声可以通过削弱接收器对信号的识别和辨别来掩盖信号。尽管研究较少，但通信系统中另一个潜在的噪声源源于信号器产生信号的方式的可变性或不一致。在配偶选择的背景下，一致性尤其重要，因为性广告信号经常随着时间的推移反复产生，并且由在信号内重复的组成部分（例如，音符和脉冲）组成。个体内部不一致的信号产生有可能掩盖个体之间的差异，而这些差异通常是接收者决策的目标。在这项对 Cope 的灰色树蛙 Hyla chrysoscelis 的研究中，我们检验了环境噪声和不一致信号独立和协同地损害物种身份识别的假设。我们根据脉搏率（物种身份的信号）在安静和旨在模拟繁殖合唱团的三个环境噪声水平下分析了雌性歧视。我们使用了不变的合成广告呼叫，或者根据在自然呼叫中观察到的个体内部变化的水平来选择脉率不一致的三个实验级别之一。平均和高于平均水平的合唱噪声会削弱脉率辨别力，但不是由于信号产生的不一致。接收器在最高级别的合唱噪声下做出决定的时间略多，但响应延迟不受不一致的影响。没有证据表明环境噪音和不一致性之间存在协同作用。我们的结果表明，环境噪声，但不是信号产生的不一致，可能会限制自然环境中物种身份信号的性选择。