Mora Emanuel C, Cobo-Cuan Ariadna, Macías-Escrivá Frank, Kössl Manfred
Research Group in Bioacoustics and Neuroethology, Faculty of Biology, Havana University, 25 St. No. 455, Vedado, CP. 10400, Havana, Cuba,
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2015 Jul;201(7):657-66. doi: 10.1007/s00359-015-1009-4. Epub 2015 Apr 19.
In certain nocturnal moth species the frequency range of best hearing shifts to higher frequencies during repeated sound stimulation. This could provide the moths with a mechanism to better detect approaching echolocating bats. However, such a dynamic up-tuning would be of little value for day-flying moths that use intra-specific acoustic communication. Here we examined if the ears of day-flying moths provide stable tuning during longer sound stimulation. Contrary to our expectations, dynamic up-tuning was found in the ear of the day-flying species Urania boisduvalii and Empyreuma pugione. Audiograms were measured with distortion-product otoacoustic emissions (DPOAEs). The level of the dominant distortion product (i.e. 2f1-f2) varied as a function of time by as much as 45 dB during ongoing acoustic stimulation, showing a systematic decrease at low frequencies and an increase at high frequencies. As a consequence, within about 2 s of acoustic stimulation, the DPOAEs audiogram shifted from low to high frequencies. Despite the up-tuning, the range of best audition still fell within the frequency band of the species-specific communication signals, suggesting that intra-specific communication should not be affected adversely. Up-tuning could be an ancestral condition in moth ears that in day-flying moths does not underlie larger selection pressure.
在某些夜间活动的蛾类物种中，在重复声音刺激期间，最佳听觉的频率范围会向更高频率转移。这可以为蛾类提供一种机制，以便更好地检测接近的回声定位蝙蝠。然而，这种动态上调对于利用种内声学通讯的日间飞行蛾类几乎没有价值。在这里，我们研究了日间飞行蛾类的耳朵在较长时间的声音刺激期间是否提供稳定的调谐。与我们的预期相反，在日间飞行物种波氏金斑蛾（Urania boisduvalii）和钩翅蛾（Empyreuma pugione）的耳朵中发现了动态上调。使用畸变产物耳声发射（DPOAE）测量听力图。在持续的声学刺激期间，主要畸变产物（即2f1 - f2）的水平随时间变化高达45分贝，在低频处呈现系统性下降，在高频处则上升。因此，在大约2秒的声学刺激内，DPOAE听力图从低频转移到高频。尽管有上调，但最佳听觉范围仍落在物种特异性通讯信号的频带内，这表明种内通讯不应受到不利影响。上调可能是蛾类耳朵的一种原始状态，在日间飞行蛾类中，它并不构成更大的选择压力的基础。
