Journal Article

Sexual Signal Evolution Outpaces Ecological Divergence during Electric Fish Species Radiation

Sullivan, John P., Lavoué, Sébastien, Arnegard, Matthew E., Zelditch, Miriam L., McIntyre, Peter B., Davis, Justin K., Harmon, Luke J., Crampton, William G. R., Hopkins, Carl D.

2010

Overview

Natural selection arising from resource competition and environmental heterogeneity can drive adaptive radiation. Ecological opportunity facilitates this process, resulting in rapid divergence of ecological traits in many celebrated radiations. In other cases, sexual selection is thought to fuel divergence in mating signals ahead of ecological divergence. Comparing divergence rates between naturally and sexually selected traits can offer insights into processes underlying species radiations, but to date such comparisons have been largely qualitative. Here, we quantitatively compare divergence rates for four traits in African mormyrid fishes, which use an electrical communication system with few extrinsic constraints on divergence. We demonstrate rapid signal evolution in theParamormyropsspecies flock compared to divergence in morphology, size, and trophic ecology. This disparity in the tempo of trait evolution suggests that sexual selection is an important early driver of species radiation in these mormyrids. We also found slight divergence in ecological traits among closely related species, consistent with a supporting role for natural selection inParamormyropsdiversification. Our results highlight the potential for sexual selection to drive explosive signal divergence when innovations in communication open new opportunities in signal space, suggesting that opportunity can catalyze species radiations through sexual selection, as well as natural selection.

• Publisher: The University of Chicago Press,University of Chicago, acting through its Press
• Subject: Adaptive radiation / Animal Communication / Animal reproduction / Animals / Biological Evolution / Biological taxonomies / Body Size / Ecological genetics / Ecological selection / Ecology / Electric Fish - physiology / Evolution / Female / Fish / Genetic Speciation / Heterogeneity / Male / Mating behavior / Mating Preference, Animal - physiology / Mormyridae / Morphology / Natural selection / Nonnative species / Phenotypic traits / Phylogenetics / Population ecology / Regression Analysis / Sexual selection / Species Specificity