Elephant nosed fishes prefer electric organ discharges (EODs) of their own species in choosing their mates, according to research to be published in the journal Biology Letters.
Philine Feulner and coauthors studied three species of the African electric fish genus Campylomormyrus (C. compressirostris, C. rhynchophorus and C. tamandua), testing the hypothesis that the fishes use EODs for mate recognition.
The authors first analysed the EOD waveforms of the three Campylomormyrus species before carrying out experiments in which female Campylomormyrus compressirostris were induced to breeding conditions and placed in the presence of two males (one conspecific and another heterospecific).
The males were separated from the female on either side of the tank by grids and the position of the focal female maintained in the presence of males overnight was recorded.
Additional experiments involved female C. compressirostris being simultaneously presented with two digitally synthesized signals consisting of independently controlled EOD waveforms (with one such sequence of pulsed intervals being chosen at random from a single C. compressirostris male recorded).
The time the focal female spent in the preference zone near the active EOD playback was recorded.
The authors found C. compressirostris and C. rhynchophorus to produce very distinct EODs that differ largely in their duration, with the EOD of C. tamandua being more similar to that of C. compressirostris than to C. rhynchophorus.
Similarly, both sets of experiments showed that female C. compressirostris preferred conspecific males over C. rhynchophorus males, but showed no significant preference for either males of C. compressirostris or C. tamandua.
Based on the results of the experiments, the authors surmise that the EOD has the potential to generate assortative mating and function as a prezygotic isolation mechanism in these weakly electric fishes and conclude he electric sense can be considered a key innovation not only regarding its primary function, ie. electrolocation, but also as an efficient trait for ~electric mate recognition.
For more information, see the paper: Feulner, PGD, M Plath, J Engelmann, F Kirschbaum and R Tiedemann (2009) Electrifying love: electric fish use species-specific discharge for mate recognition. Biology Letters, doi: 10.1098/rsbl.2008.0566