Comparative analysis of the jamming avoidance response in African and South American wave-type electric fishes.

African wave-type electric fish, Gymnarchus, and South American wave-type electric fish, Eigenmannia, have evolved electrosensory and electromotor systems independently. Nevertheless, they exhibit a similar electrical behavior, the jamming avoidance response (JAR). When two individuals with slightly different frequencies of electric organ discharge (EOD) meet, they shift discharge frequencies away from each other to avoid mutual jamming of their electrolocation systems. These two genera of electric fishes perform this behavior using an identical set of complex computational rules. Reflecting their independent evolution, however, neuronal implementation of the computational steps appears to take different forms. One of the essential computational steps, phase comparison, is performed in the hindbrain in Gymnarchus and in the midbrain in Eigenmannia. The comparison of these two species in this paper revealed an example of how different brain structures perform functionally similar tasks in independently evolved systems that have a similar overall behavioral function.