Dobbs Olivia L, Talavera Janelle B, Rossi Sarina M, Menjivar Stephanie, Gray David A
Department of Biology California State University Northridge Northridge CA USA.
Ecol Evol. 2020 Sep 29;10(21):12364-12371. doi: 10.1002/ece3.6866. eCollection 2020 Nov.
Signals are important for communication and mating, and while they can benefit an individual, they can also be costly and dangerous. Male field crickets call in order to attract female crickets, but gravid females of a parasitoid fly species, , are also attracted to the call and use it to pinpoint male cricket hosts. Conspicuousness of the call can vary with frequency, amplitude, and temporal features. Previous work with this system has only considered temporal variation in cricket calls, both large scale, that is, amount of calling and at what time of evening, and small scale, that is, aspects of chirp rate, pulse rate, and numbers of pulses per chirp. Because auditory perception in both crickets and flies relies on the matching of the peak frequency of the call with the peripheral sensory system, peak frequency may be subject to selection both from female crickets and from female flies. Here, we used field playbacks of four different versions of the same male calling song that only differed in peak frequency (3.3, 4.3, 5.3, and 6.3 kHz) to test the relative attractiveness of the calls to female crickets and female flies. Our results clearly show that lower frequency calls enhance male safety from fly parasitism, but that the enhanced safety would come at a cost of reduced attraction of female crickets as potential mates. The results imply that eavesdropper pressure can disrupt the matched coevolution of signalers and receivers such that the common concept of matched male-female signaler-receiver coevolution may actually be better described as male-female-predator signaler-receiver-eavesdropper coevolution.
信号对于交流和交配很重要，虽然它们能使个体受益，但也可能代价高昂且危险。雄性田蟋蟀鸣叫以吸引雌性田蟋蟀，然而一种寄生蝇的怀孕雌蝇也会被这种叫声吸引，并利用它来确定雄性田蟋蟀宿主的位置。叫声的显著程度会随频率、振幅和时间特征而变化。此前针对该系统的研究仅考虑了田蟋蟀叫声的时间变化，包括大规模的，即鸣叫的数量和傍晚的时间，以及小规模的，即啁啾率、脉冲率和每次啁啾的脉冲数等方面。由于田蟋蟀和寄生蝇的听觉感知都依赖于叫声的峰值频率与外周感觉系统的匹配，峰值频率可能会受到雌性田蟋蟀和雌性寄生蝇的选择。在此，我们使用了同一只雄性田蟋蟀鸣叫歌曲的四个不同版本进行野外回放，这些版本仅在峰值频率（3.3、4.3、5.3和6.3千赫兹）上有所不同，以测试这些叫声对雌性田蟋蟀和雌性寄生蝇的相对吸引力。我们的结果清楚地表明，较低频率的叫声能提高雄性田蟋蟀免受寄生蝇寄生的安全性，但这种增强的安全性是以减少对雌性田蟋蟀作为潜在配偶的吸引力为代价的。这些结果意味着窃听者的压力会扰乱信号发送者和接收者的匹配协同进化，以至于通常认为的雄性 - 雌性信号发送者 - 接收者的匹配协同进化这一概念，实际上可能更好地被描述为雄性 - 雌性 - 捕食者信号发送者 - 接收者 - 窃听者的协同进化。
