BIOACOUSTIC BEHAVIOR OF AFRICAN FISHES (MORMYRIDAE) - POTENTIAL CUES FOR SPECIES AND INDIVIDUAL RECOGNITION IN POLLIMYRUS

An analysis of the natural bioacoustic signals made by two closely rel ated African fishes (P. adspersus and P. isidori) revealed that these species separated along several acoustic dimensions that are likely to be important for species isolation. Both species produced grunts that were composed of a trains of pulses, but the pulse repetition rates w ere distinctly different (56+/-3 s.d, vs 44+/-4 s.d, pps), Complex ton e bursts (moans) were also used, but the species differed substantiall y in the location of the fundamental peak (240 Hz+/-12 s.d. vs 332 Hz/-34 s.d.). Some P, adspersus males sustained these tones for over a s econd (812 ms+/-495 s.d.), whereas P, isidori produced shorter tones ( 121 ms+/-35 s.d,), During interactions with females, the two species p roduced the grunts and moans in distinct species-typical patterns: P. adspersus males alternated grunts with moans and P, isidori produced a single grunt followed by a succession of moans. A detailed analysis o f identified individual P. adspersus showed that acoustic features con stituted individual signatures which could be used by conspecifics to identify individuals. Grunt spectral peak frequency was shown to be a good predictor of male mass, with peak frequency decreasing at 72 Hz p er grant. Simulated standardized courtship encounters with females rev ealed that males differ markedly in their apparent ability to produce sustained moans and it is suggested that this may be particularly impo rtant to females in mate selection. (C) 1997 Acoustical Society of Ame rica.