Electrocommunication in pulse Gymnotiformes: the role of EOD time course in species identification.

Abstract

Understanding how individuals detect and recognize signals emitted by conspecifics is fundamental to discussions of animal communication. The species pair Gymnotus omarorum and Brachyhypopomus gauderio, found in syntopy in Uruguay, emit species-specific electric organ discharge (EOD) that can be sensed by both species. The aim of this study was to unveil whether either of these species is able to identify a conspecific EOD, and to investigate distinctive recognition signal features. We designed a forced-choice experiment using a natural behavior (i.e. tracking electric field lines towards their source) in which each fish had to choose between a conspecific and a heterospecific electric field. We found a clear pattern of preference for a conspecific waveform even when pulses were played within 1 Hz of the same rate. By manipulating the time course of the explored signals, we found that the signal features for preference between conspecific and heterospecific waveforms were embedded in the time course of the signals. This study provides evidence that pulse Gymnotiformes can recognize a conspecific exclusively through species-specific electrosensory signals. It also suggests that the key signal features for species differentiation are probably encoded by burst coder electroreceptors. Given these results, and because receptors are sharply tuned to amplitude spectra and also tuned to phase spectra, we extend the electric color hypothesis used in the evaluation of objects to apply to communication signals.

A propagação dos pulsos elétricos gerados por Gymnotus carapo

“…O uso de dipolos para tentar estimular de modo realista os animais reais tem sido amplamente adotado na literatura. (21,(32)(33)(34)(35) Nossos resultados até agora têm mostrado que o uso de dipolos não é adequado quando o peixe real está livre pra se mover e a distância entre ele e o peixe artificial é maior que algumas dezenas de cm, pois ele vai perceber que seu colega produz um sinal que varia no espaço de um modo estranho, não natural, ou pelo menos não como deveria variar se ele fosse da mesma espécie. Por outro lado, talvez, o comportamento anômalo dos dipolos à maiores distâncias, não seja tão importante, já que o peixe real pode se aproximar do peixe artificial e interagir de alguma forma.…”