Convergence to the tiniest detail: vocal sac structure in torrent-dwelling frogs

ELIAS-COSTA, AGUSTIN J.; FAIVOVICH, J.

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 128 p. 390 - 402

0024-4066

Cascades and fast-flowing streams impose severe restrictions on acoustic communication, with loud broadbandbackground noise hampering signal detection and recognition. In this context, diverse behavioural features, such asultrasound production and visual displays, have arisen in the evolutionary history of torrent-dwelling amphibians.The importance of the vocal sac in multimodal communication is being increasingly recognized, and recently anew vocal sac visual display has been discovered: unilateral inflation of paired vocal sacs. In the diurnal streambreedingHylodidae from the Atlantic forest, where it was first described, this behaviour is likely to be enabled bya unique anatomical configuration of the vocal sacs. To assess whether other taxa share this exceptional structure,we surveyed torrent-dwelling species with paired vocal sacs across the anuran tree of life and examined the vocalsac anatomy of exemplar species across 18 families. We found striking anatomical convergence among hylodids andspecies of the distantly related basal ranid genera Staurois, Huia, Meristogenys and Amolops. Ancestral characterstate reconstruction identified three new synapomorphies for Ranidae. Furthermore, we surveyed the vocal sacconfiguration of other anuran species that perform visual displays and report observations on what appears to beunilateral inflation of paired vocal sacs, in Staurois guttatus ? an extremely rare behaviour in anurans.