Sound Discrimination by the Bicolor Damselfish, Eupomacentrus Partitus

Abstract

ABSTRACT Males of laboratory and field colonies of the bicolor damselfish, Eupomacentrus partitus, showed significantly greater response to playback of courtship sounds of conspecifics than to playback of structurally similar and fully analogous sounds of two closely related and sympatric congenerics, E. leucostictus and E. planifrons. Relative levels of responsiveness by these colonies differed, however, in that laboratory males showed a significant difference in courtship during playback periods of congeneric sounds (recorded in the laboratory) whereas field males showed no such difference. Field males, though responding well to typical laboratory sounds from conspecifics during tests which did not include playback of field sounds from conspecifics, failed to respond well when playback periods did include such field sounds. Present evidence demonstrates that male bicolors possess an excellent discriminative ability within the acoustic modality and that such discrimination is based on some factor of the structural patterning, in time, of the experimental sounds. Present evidence also indicates that the observed response differentials noted during experiments were the result of a slight, but important, difference in at least one typical parameter, i.e., the pulse interval.