Title

Sexual Signal Evolution Outpaces Ecological Divergence during Electric Fish Species Radiation

Authors

Authors

M. E. Arnegard; P. B. McIntyre; L. J. Harmon; M. L. Zelditch; W. G. R. Crampton; J. K. Davis; J. P. Sullivan; S. Lavoue;C. D. Hopkins

Comments

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Abbreviated Journal Title

Am. Nat.

Keywords

speciation; sexual selection; key innovation; private communication; channel; electric organ discharge; MALAWI CICHLID FISHES; ORGAN DISCHARGE; MORMYRID FISH; ADAPTIVE; RADIATION; COMMUNICATION SIGNALS; SYMPATRIC SPECIATION; MOLECULAR; MARKERS; NATURAL-SELECTION; TROPHIC POSITION; CENTRAL-AFRICA; Ecology; Evolutionary Biology

Abstract

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 the Paramormyrops species 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 in Paramormyrops diversification. 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.

Journal Title

American Naturalist

Volume

176

Issue/Number

3

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

335

Last Page

356

WOS Identifier

WOS:000280621000008

ISSN

0003-0147

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