Hearing in the African lungfish (Protopterus annectens): pre-adaptation to pressure hearing in tetrapods?
Hearing in the African lungfish (Protopterus annectens): pre-adaptation to pressure hearing in tetrapods?
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DOI：
10.1098/rsbl.2010.0636
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发表时间：
2011-02-23
期刊：
影响因子：
3.3
通讯作者：
Madsen, Peter T.
中科院分区：
文献类型：
--
作者：
Christensen-Dalsgaard, Jakob;Brandt, Christian;Madsen, Peter T.
肺鱼是四足动物的近亲，现代肺鱼的耳朵更像四足动物的耳朵，而不是鳍鱼的耳朵，因此对理解早期四足动物听觉的进化很有意义。水到陆地的过渡导致了与空气传播声压检测相关的四足动物耳的重大变化，这一点在所有主要四足动物组中的鼓膜耳的晚期和独立起源中得到了证明。调查肺鱼的压力和振动检测，我们测量了5个西非肺鱼（Protopterus annectens）的灵敏度和频率响应，使用脑干电位诱发校准的声音和振动刺激在空气和水中。我们发现肺鱼的耳朵像最近的两栖动物一样对低频振动敏感性很好，但对空气传播的声音敏感性较差。当受到空气传播的声音刺激时，头骨显示出高于100 Hz的可测量振动，但耳朵在这些频率下显然不敏感，这表明肺鱼的耳朵既不适应也不预先适应空中听觉。因此，如果肺鱼的耳朵是早期四足动物耳朵的模型，那么它们的听觉灵敏度仅限于陆地上的非常低的频率，主要是由基质传播的振动介导的。
Lungfishes are the closest living relatives of the tetrapods, and the ear of recent lungfishes resembles the tetrapod ear more than the ear of ray-finned fishes and is therefore of interest for understanding the evolution of hearing in the early tetrapods. The water-to-land transition resulted in major changes in the tetrapod ear associated with the detection of air-borne sound pressure, as evidenced by the late and independent origins of tympanic ears in all of the major tetrapod groups. To investigate lungfish pressure and vibration detection, we measured the sensitivity and frequency responses of five West African lungfish (Protopterus annectens) using brainstem potentials evoked by calibrated sound and vibration stimuli in air and water. We find that the lungfish ear has good low-frequency vibration sensitivity, like recent amphibians, but poor sensitivity to air-borne sound. The skull shows measurable vibrations above 100 Hz when stimulated by air-borne sound, but the ear is apparently insensitive at these frequencies, suggesting that the lungfish ear is neither adapted nor pre-adapted for aerial hearing. Thus, if the lungfish ear is a model of the ear of early tetrapods, their auditory sensitivity was limited to very low frequencies on land, mostly mediated by substrate-borne vibrations.