Auditory sexual difference in the large odorous frog Odorrana graminea

Abstract

Acoustic communication is an important behavior in frog courtship. Male and female frogs of most species, except the concave-eared torrent frog Odorrana tormota, have largely similar audiograms. The large odorous frogs (Odorrana graminea) are sympatric with O. tormota, but have no ear canals. The difference in hearing between two sexes of the frog is unknown. We recorded auditory evoked near-field potentials and single-unit responses from the auditory midbrain (the torus semicircularis) to determine auditory frequency sensitivity and threshold. The results show that males have the upper frequency limit at 24kHz and females have the upper limit at 16kHz. The more sensitive frequency range is 3-15kHz for males and 1-8kHz for females. Males have the minimum threshold at 11kHz (58dB SPL), higher about 5dB than that at 3kHz for females. The best excitatory frequencies of single units are mostly between 3 and 5kHz in females and at 7-8kHz in males. The underlying mechanism of auditory sexual differences is discussed.