Date:
Julia A. Clarke
John A. Wilson Professor
The University of Texas at Austin
Evolution of acoustic allometry in birds and the estimation of extinct dinosaur vocalizations
Abstract: Fundamental frequency (F0), perceived as pitch, is typically the lowest frequency component of a vocalization. Ecologically salient, it is related to the scaling and properties of the sound source (vocal folds in the mammalian larynx or avian syrinx). Its component vocal folds, and F0, are known to scale with body size in frogs, mammals, and some avian subclades, although this scaling relationship is known to show clade-specific shifts. In analyses of more than 1100 extant avian taxa, we find that body size significantly explains fundamental frequency across the smallest and largest known birds. While most birds are share a scaling relationship estimated to be ancestral to the clade, we identify numerous shifts in slope and intercept that characterize clades with novelties in the sound source: intrinsic muscles and change in sound source number. Changes in the vocal tract are also linked to changes in scaling relationship; both tracheal elongation and closed mouth vocal behavior are associated with lower frequencies than expected for a given body size. However, the syrinx and larynx show similar scaling relationships with F0, supporting shared physical properties of these sound sources. These results allow us estimate related frequency characteristics of extinct dinosaur sounds and associated uncertainty.
Host: Stephanie Pierce Lab
