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First published online May 19, 2008
Journal of Experimental Biology 211, 1814-1818 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.015982

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Molecular evolution of communication signals in electric fish

Harold H. Zakon^*, Derrick J. Zwickl, Ying Lu and David M. Hillis

Sections of Neurobiology and Integrative Biology, The University of Texas, Austin, TX 78712, USA

View larger version (5K): [in this window] [in a new window]   Fig. 1. EOD pulses from the five species of electric fish used in the molecular analysis in Fig. 2. (A) A single pulse of the wave-like EOD of Sternopygus macrurus, the gold-lined black knifefish; (B) a single pulse of the wave-like EOD of Apteronotus leptorhynchus, the brown ghost; (C) Electrophorus electricus, the electric eel; (D) Brachyhypopomus pinnicaudatus, the pintail knifefish; and (E) Gnathonemus petersii, the elephant nose mormyrid. S. macrurus and A. leptorhynchus are wave-type fish whereas the other three species are pulse fish. All are gymnotiforms except for G. petersii. All pulses are on the same time scale; the EOD pulse of G. petersii is also shown on an expanded time scale to the right (indicated by the arrow). Reproduced with permission (Zakon et al., 2006).

View larger version (12K): [in this window] [in a new window]   Fig. 2. Gene tree of Nav1.4a with the estimated number of non-synonymous/synonymous substitutions for each branch. Red branches indicate lineages in which Nav1.4a is known to be lost from muscle (the dotted line in E. electricus indicates that its loss is likely but not yet tested), and the blue branch indicates that Nav1.4a expression is not lost from muscle. Note the much longer branch lengths of the electric fish lineages from which Nav1.4a was lost from muscle and the high ratio of non-synonymous to synonymous substitutions in these branches indicative of elevated rates of evolutionary change. Reproduced with permission (Zakon et al., 2006).

View larger version (62K): [in this window] [in a new window]   Fig. 3. Non-conserved amino acid substitutions occur in a number or regions of the Na+ channel involved in inactivation of the Na+ current. Mormyr, mormyrid; Gymnot, gymnotiform. (A) Schematic illustration of the Na+ channel. (B) S4–S5 linker in domain II; (C) S4–S5 linker in domain III; (D,E) different parts of the inactivation `ball' or hinged lid in the loop between domains III and IV. Amino acid sequences below the dashed line were used in the PAML analysis. Those above were not used in the analysis but are shown for reference. Red letters are non-conservative amino acid substitutions. Triangles represent amino acid sites at which mutations in human Na+ channels cause diseases. The asterisk represents a site at which there are amino acid changes in gymnotiform fish and at which a mutation in humans is related to a disease. Reproduced with permission (Zakon et al., 2006).