The evolution of deafness: the causes and consequences of ear loss in frogs

Colorado State University, Fort Collins CO

Investigators

Abstract

This award addresses the evolution of sensory system reductions, that is, the decreases in structural size or complexity or functional changes that limit an animal?s capacity to sense the environment. Most terrestrial tetrapods have tympanic ears that convert the external vibrations of air particles to vibrations within the fluid-filled inner ear cavity containing the sensory end organs via middle ear structures. Diverse frogs and toads, however, have secondarily lost the outer and middle ears in independent evolutionary events, despite the general tendency for anurans to use acoustic signals for the social interactions that facilitate reproduction. This award supports an international collaboration designed to integrate natural history, auditory physiology, functional morphology, and evolutionary development to detail the causes and consequences of evolutionary transitions. The study system chosen is Pristimantis in Ecuador. Initial trips will provide the opportunity to locate populations of earless Pristimantis frogs, describe basic natural history of the earless species, and collect specimens for preliminary genetic and morphological analyses. The intention is to expand on this preliminary information in future studies. The multi-disciplinary, international team will include scientists from Ecuador, Denmark, and The Netherlands. This award will support two female graduate students from the US in for trips to Ecuador, introducing them to fieldwork in South America and to the diverse expertise of the collaborating key individuals. Furthermore, Ecuadorian researchers and students would have a unique opportunity to learn about auditory physiology via an educational workshop. Results of this project are to be shared with the broader public via undergraduate teaching and lectures for the public in the US and in Ecuador. Finally this work will aid in frog conservation efforts.