The Eyes Have It: Regulatory and Structural Changes Both Underlie Cichlid Visual Pigment Diversity
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Author/Creator ORCID
Date
2009-12-22
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Citation of Original Publication
Hofmann CM, O’Quin KE, Marshall NJ, Cronin TW, Seehausen O, et al. (2009) The Eyes Have It: Regulatory and Structural Changes Both Underlie Cichlid Visual Pigment Diversity. PLoS Biol 7(12): e1000266. doi:10.1371/journal.pbio.1000266
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Attribution 3.0 United States (CC BY 3.0 US)
Attribution 3.0 United States (CC BY 3.0 US)
Abstract
A major goal of evolutionary biology is to unravel the molecular genetic mechanisms that underlie functional diversification
and adaptation. We investigated how changes in gene regulation and coding sequence contribute to sensory diversification
in two replicate radiations of cichlid fishes. In the clear waters of Lake Malawi, differential opsin expression generates diverse
visual systems, with sensitivities extending from the ultraviolet to the red regions of the spectrum. These sensitivities fall
into three distinct clusters and are correlated with foraging habits. In the turbid waters of Lake Victoria, visual sensitivity is
constrained to longer wavelengths, and opsin expression is correlated with ambient light. In addition to regulatory changes,
we found that the opsins coding for the shortest- and longest-wavelength visual pigments have elevated numbers of
potentially functional substitutions. Thus, we present a model of sensory evolution in which both molecular genetic
mechanisms work in concert. Changes in gene expression generate large shifts in visual pigment sensitivity across the
collective opsin spectral range, but changes in coding sequence appear to fine-tune visual pigment sensitivity at the shortand
long-wavelength ends of this range, where differential opsin expression can no longer extend visual pigment
sensitivity.