Pygmy mouse songs reveal anatomical innovations underlying acoustic signal elaboration in rodents [RESEARCH ARTICLE]

Tobias Riede and Bret Pasch Elaborate animal communication displays are often accompanied by morphological and physiological innovations. In rodents, acoustic signals used in reproductive contexts are produced by two distinct mechanisms, but the underlying anatomy that facilitates such divergence is poorly understood. ‘Audible’ vocalizations with spectral properties between 500 Hz and 16 kHz are thought to be produced by flow-induced vocal fold vibrations, whereas ‘ultrasonic’ vocalizations with fundamental frequencies above 19 kHz are produced by an aerodynamic whistle mechanism. Baiomyine mice (genus Baiomys and Scotinomys) produce complex frequency modulated songs that span these traditional distinctions and represent important models to understand the evolution of signal elaboration. We combined acoustic analyses of spontaneously vocalizing northern pygmy mice (B. taylori) mice in air and light gas atmosphere with morphometric analyses of their vocal apparatus to infer the mechanism of vocal production. Increased fundamental frequencies in heliox indicated that pygmy mouse songs are produced by an aerodynamic whistle mechanism supported by the presence of a ventral pouch and alar cartilage. Comparative analyses of the larynx and ventral pouch size among four additional ultrasonic whistle-producing rodents indicate that the unusually low ‘ultrasonic’ frequencies (relative to body size) of pygmy mice songs are associated with an enlarged ...

Source: Journal of Experimental Biology - May 25, 2020 Category: Biology Authors: Riede, T., Pasch, B. Tags: RESEARCH ARTICLE Source Type: research