Potential Use of Low-Frequency Sounds by Baleen Whales for Probing the Environment: Evidence from Models and Empirical Measurements

摘要

Natural variability within a population is the fodder for selection, and an organism with traits best adapted to its environment is most likely to transfer genes to the next generation. Here we take the simplistic view that acoustic characteristics shared broadly across multiple species are considered more ancestral than features only shared at the species level. This conceptual framework is the basis for gauging the degree to which, and the approximate order in which the physical environment has effected the features of baleen whale (mysticetes) sounds. Comparison of mysticete sound characteristics and evaluation based on several predictions of sonar equations support the hypothesis that sounds from shallow water and deep water species are matched to their respective environments so as to optimize underwater sound transmission for long-range communication. We propose that in the marine environment the influences of physical acoustics imposed strong selective pressures on the acoustic features of whale sounds. In some species for which selection has favored very long-range communication signals, we propose a secondarily derived function, that animals use reflections of their sounds as a simple form of echo-ranging to navigate and orient relative to physical features of the ocean.