Bohn Kirsten M, Moss Cynthia F, Wilkinson Gerald S
Department of Biology, University of Maryland, College Park, MD 20742, USA.
Biol Lett. 2006 Dec 22;2(4):561-4. doi: 10.1098/rsbl.2006.0501.
Echolocating bats are auditory specialists, with exquisite hearing that spans several octaves. In the ultrasonic range, bat audiograms typically show highest sensitivity in the spectral region of their species-specific echolocation calls. Well-developed hearing in the audible range has been commonly attributed to a need to detect sounds produced by prey. However, bat pups often emit isolation calls with low-frequency components that facilitate mother-young reunions. In this study, we examine whether low-frequency hearing in bats exhibits correlated evolution with (i) body size; (ii) high-frequency hearing sensitivity or (iii) pup isolation call frequency. Using published audiograms, we found that low-frequency hearing sensitivity is not dependent on body size but is related to high-frequency hearing. After controlling for high-frequency hearing, we found that low-frequency hearing exhibits correlated evolution with isolation call frequency. We infer that detection and discrimination of isolation calls have favoured enhanced low-frequency hearing because accurate parental investment is critical: bats have low reproductive rates, non-volant altricial young and must often identify their pups within large crèches.
使用回声定位的蝙蝠是听觉专家，拥有跨越几个八度的敏锐听力。在超声波范围内，蝙蝠的听力图通常显示，在其特定物种回声定位叫声的频谱区域内，它们具有最高的灵敏度。在可听范围内发达的听力通常被认为是出于探测猎物发出声音的需要。然而，蝙蝠幼崽经常发出带有低频成分的隔离叫声，这有助于母子团聚。在这项研究中，我们研究了蝙蝠的低频听力是否与以下因素存在协同进化关系：（i）体型；（ii）高频听力灵敏度；或（iii）幼崽隔离叫声频率。利用已发表的听力图，我们发现低频听力灵敏度并不依赖于体型，而是与高频听力有关。在控制了高频听力之后，我们发现低频听力与隔离叫声频率存在协同进化关系。我们推断，对隔离叫声的探测和辨别有利于增强低频听力，因为准确的亲代投资至关重要：蝙蝠繁殖率低，幼崽不能飞行且需要照顾，而且它们必须经常在大型育幼群体中识别自己的幼崽。
