title: Drift-driven evolution of electric signals in a Neotropical knifefish.
abstract: Communication signals are highly diverse traits. This diversity is usually assumed to be shaped by selective forces, whereas the null hypothesis of divergence through drift is often not considered. In Panama, the weakly electric fish Brachyhypopomus occidentalis is widely distributed in multiple independent drainage systems, which provide a natural evolutionary laboratory for the study of genetic and signal divergence in separate populations. We quantified geographic variation in the electric signals of 109 fish from five populations, and compared it to the neutral genetic variation estimated from cytochrome oxidase I (COI) sequences of the same individuals, to test whether drift may be driving divergence of their signals. Signal distances were highly correlated with genetic distances, even after controlling for geographic distances, suggesting that drift alone is sufficient to explain geographic variation in electric signals. Significant differences at smaller geographic scales (within drainages) showed, however, that electric signals may evolve at a faster rate than expected under drift, raising the possibility that additional adaptive forces may be contributing to their evolution. Overall, our data point to stochastic forces as main drivers of signal evolution in this species and extend the role of drift in the evolution of communication systems to fish and electrocommunication.
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada. sophiepicq@gmail.com.|Smithsonian Tropical Research Institute, Apartado 0843-03092 Balboa, Ancón, Republic of Panama. sophiepicq@gmail.com.|Current Address: GEOMAR Helmholtz Centre for Ocean Research Kiel, Evolutionary Ecology of Marine Fishes, Düsternbrooker Weg 20, Kiel, 24105, Germany. sophiepicq@gmail.com.
authors.forename: Sophie
authors.initials: S
authors.lastname: Picq
authors.affiliation: Smithsonian Tropical Research Institute, Apartado 0843-03092 Balboa, Ancón, Republic of Panama.|Current Address: Museum of Natural Science, Department of Biological Sciences, Louisiana State University, 119 Foster Hall, Baton Rouge, LA.
authors.forename: Fernando
authors.initials: F
authors.lastname: Alda
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada.|Smithsonian Tropical Research Institute, Apartado 0843-03092 Balboa, Ancón, Republic of Panama.|Current Address: Patricia and Phillip Frost Museum of Science, 3280 South Miami Avenue, Miami, FL.
authors.forename: Eldredge
authors.initials: E
authors.lastname: Bermingham
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Krahe
mesh_terms: D000819:Animal Communication; D000818:Animals; D005075:Biological Evolution; D004272:DNA, Mitochondrial / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics; D040961:Genetic Drift; D023702:Gymnotiformes / Q000235:genetics / Q000502:physiology*; D008297:Male; D010176:Panama; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial; D029941:Fish Proteins; D003576:Electron Transport Complex IV
keywords: Animal communication; Brachyhypopomus occidentalis; electric organ discharge; genetic drift; signaling/courtship; weakly electric fish