Weakly electric fish 1 PP

Chirp structure and EOD frequency are sexually dimorphic to different extents across wave-type species. In Apteronotids, males often have lower EOD frequency than females but EOD frequency chirping can be sexually dimorphic in a number of different ways (Smith 2013, 2422; Ho et al. 2013, 335; Ho et al. 2010, 1050). For example, A. albifrons males have lower EOD frequencies than females while A. leptorhynchus males have a higher EOD frequency than females (Smith 2013, 2422). Additionally, in A. leptorhynchus, males chirp more than females but their chirp complexity is similar while in A. bonapartii and A. devenanzii chirp complexity and not chirp rate is higher in males than in females (Smith 2013, 2428; Ho et al. 2010, 1059). Another Apteronotid, Sternarchogiton nattereri, shows no sexual dimorphism, as males and females show no discernible difference in EOD frequency, chirp rate, or chirp form (Ho et al. 2013,337). Instead, S. nattereri shows differences in EOD frequency that are dependent on male morphology, as toothed males show higher EOD frequency than toothless males (Fernandes et al. 2010, 660). In the wave-type Gymnotiform Gymnotus omarorum, and unlike in many of the aforementioned wave-type Apteronotids, electric signalling is sexually monomorphic (Batista et al. 2012, 398). Such sexually monomorphic electrocommunicative behaviour has also been observed in other non-Apteronotid genera such Eigenmannia and Sternopygus (Smith 2013, 2422).