We are investigating complex acoustic pattern recognition in túngara frogs, Physalaemus pustulosus, by concentrating on how and why females recognize the conspecific advertisement call. The approach I use in collaboration with Dr. Rand of the Smithsonian Tropical Research Institute is multidisciplinary and asks: What is the sensory basis of call recognition and preferences? What is the adaptive significance of female signal preferences? How has the past evolutionary history of the brain influenced the neural-computational strategies used by females in decoding acoustic signals? The approaches my colleagues and I use include quantification of naturalistic behavior in the wild; controlled behavioral tests of female phonotaxis preferences; neurophysiological characterization of the auditory system (in collaboration with Dr. Wilczynski, also a member of this Center); and, molecular phylogenetics analysis of this species and its close relatives (in collaboration with Drs. Cannatella and Hillis of the Section of Integrative Biology).

Some of our results show that (1) females prefer more complex calls; (2) simultaneous stimulation of two auditory end-organs account for this preference; (3) the sensory basis of the preference for complex calls precedes the evolution of the complex call; and, (4) more generally, the types of signal decoded by the ancestors of the túngara frog influence the manner in which túngara frog females decode signals today.

For more information on this and other research in the Ryan Lab, go to: http://www.esb.utexas.edu/ryan