SELECTIVE PHONOTAXIS TO ADVERTISEMENT CALLS IN THE GRAY TREEFROG HYLAVERSICOLOR - BEHAVIORAL-EXPERIMENTS AND NEUROPHYSIOLOGICAL CORRELATES

1. The significance of particular acoustic properties of advertisement calls for selective phonotaxis by the gray treefrog, Hyla versicolor (= HV), was studied behaviorally and neurophysiologically. Most stimul i were played back at 85 dB SPL, a level typically measured at 1-2 m f rom a calling male. 2. Females preferred stimuli with conspecific puls e shapes at 20 degrees and 24 degrees C, but not at 16 degrees C. Test s with normal and time-reversed pulses indicated the preferences were not influenced by the minor differences in the long-term spectra of pu lses of different shape. 3. Pulse shape and rate had synergistic or an tagonistic effects on female preferences depending on whether the valu es of one or both of these properties in alternative stimuli were typi cal of those in HV or heterospecific (H. chrysoscelis = HC) calls. 4. More auditory neurons in the torus semicircularis were temporally sele ctive to synthetic calls (90%) than to sinusoidally AM tones and noise (< 70%). 5. Band-pass neurons were tuned to AM rates of 15-60 Hz. Neu rons were more likely to be tuned to HV AM rates (< 40 Hz) when stimul i had pulses with HV rather than HC shapes. 6. Sharp temporal tuning w as uncommon and found only in neurons with band-pass or low-pass chara cteristics. 7. Many neurons differed significantly in response to HV a nd HC stimulus sets. Maximum spike rate was more often elicited by an HV stimulus (74%) than by an HC stimulus (24%). 8. Differences in spik e rates elicited by HV and HC stimuli were attributable to combination s of differences in the rise times and shapes of the pulses.