The eyes have it: regulatory and structural changes both underlie cichlid visual pigment diversity

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...

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Bibliographic Details
Published in:PLoS biology 2009-12, Vol.7 (12), p.e1000266-e1000266
Main Authors: Hofmann, Christopher M, O'Quin, Kelly E, Marshall, N Justin, Cronin, Thomas W, Seehausen, Ole, Carleton, Karen L
Format: Article
Language:English
Subjects:
Adaptation, Biological
Africa, Eastern
Amino acids
Analysis
Animals
Cichlidae
Cichlids - physiology
Control
Debates
Ecology/Physiological Ecology
Ecosystem
Evolutionary Biology
Evolutionary Biology/Evolutionary and Comparative Genetics
Evolutionary Biology/Evolutionary Ecology
Eye
Gene expression
Gene Expression Profiling
Genetic aspects
Genetic Speciation
Genetics
Lakes
Molecular Biology/Molecular Evolution
Open Reading Frames
Opsins - genetics
Opsins - metabolism
Phylogenetics
Physical properties
Physiological aspects
Pigments
Statistical methods
Structure
Studies
Varieties
Vision, Ocular - physiology
Visual pigments
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Summary: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 short- and long-wavelength ends of this range, where differential opsin expression can no longer extend visual pigment sensitivity.
ISSN:1545-7885
1544-9173
1545-7885
DOI:10.1371/journal.pbio.1000266