Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0205, USA.
J Acoust Soc Am. 2013 Sep;134(3):2293-301. doi: 10.1121/1.4817832.
Beaked whale echolocation signals are mostly frequency-modulated (FM) upsweep pulses and appear to be species specific. Evolutionary processes of niche separation may have driven differentiation of beaked whale signals used for spatial orientation and foraging. FM pulses of eight species of beaked whales were identified, as well as five distinct pulse types of unknown species, but presumed to be from beaked whales. Current evidence suggests these five distinct but unidentified FM pulse types are also species-specific and are each produced by a separate species. There may be a relationship between adult body length and center frequency with smaller whales producing higher frequency signals. This could be due to anatomical and physiological restraints or it could be an evolutionary adaption for detection of smaller prey for smaller whales with higher resolution using higher frequencies. The disadvantage of higher frequencies is a shorter detection range. Whales echolocating with the highest frequencies, or broadband, likely lower source level signals also use a higher repetition rate, which might compensate for the shorter detection range. Habitat modeling with acoustic detections should give further insights into how niches and prey may have shaped species-specific FM pulse types.
齿鲸的回声定位信号主要是调频（FM）上扫脉冲，似乎具有物种特异性。生态位分离的进化过程可能导致用于空间定位和觅食的齿鲸信号产生分化。确定了八种齿鲸的 FM 脉冲，以及五种不同的未知物种的脉冲类型，但推测来自齿鲸。目前的证据表明，这五种不同但未识别的 FM 脉冲类型也是物种特异性的，每种类型都是由一个单独的物种产生的。成年体长与中心频率之间可能存在关系，较小的鲸鱼产生更高频率的信号。这可能是由于解剖学和生理学的限制，也可能是一种进化适应，用于检测较小的猎物，较小的鲸鱼使用更高的频率具有更高的分辨率。更高的频率的缺点是检测范围更短。使用最高频率或宽带进行回声定位的鲸鱼，可能会降低声源级信号，同时也会使用更高的重复率，这可能会补偿较短的检测范围。通过声学探测进行栖息地建模，应该可以进一步了解生态位和猎物如何塑造特定于物种的 FM 脉冲类型。
