4104 The Journal of Experimental Biology 210, 4104-4122 Published by The Company of Biologists 2007 doi:10.1242/jeb.007930 Phylogenetic comparative analysis of electric communication signals in ghost knifefishes (Gymnotiformes: Apteronotidae) Cameron R. Turner1,2,*, Maksymilian Derylo3,4, C. David de Santana5,6, José A. Alves-Gomes5 and G. Troy Smith1,2,7 1Department of Biology, 2Center for the Integrative Study of Animal Behavior (CISAB) and 3CISAB Research Experience for Undergraduates Program, Indiana University, Bloomington, IN 47405, USA, 4Dominican University, River Forest, IL 60305, USA, 5Laboratório de Fisiologia Comportamental (LFC), Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, AM 69083-000, Brazil, 6Smithsonian Institution, National Museum of Natural History, Division of Fishes, Washington, DC 20560, USA and 7Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA *Author for correspondence (e-mail:
[email protected]) Accepted 30 August 2007 Summary Electrocommunication signals in electric fish are diverse, species differences in these signals, chirp amplitude easily recorded and have well-characterized neural control. modulation, frequency modulation (FM) and duration were Two signal features, the frequency and waveform of the particularly diverse. Within this diversity, however, electric organ discharge (EOD), vary widely across species. interspecific correlations between chirp parameters suggest Modulations of the EOD (i.e. chirps and gradual frequency that mechanistic trade-offs may shape some aspects of rises) also function as active communication signals during signal evolution. In particular, a consistent trade-off social interactions, but they have been studied in relatively between FM and EOD amplitude during chirps is likely to few species. We compared the electrocommunication have influenced the evolution of chirp structure.