Copyright © 2004 The American Society of Human Genetics. All rights reserved.
The American Journal of Human Genetics, Volume 75, Issue 3, 363-375, 1 September 2004
doi:10.1086/423287
Signatures of Selection and Gene Conversion Associated with Human Color Vision Variation
Brian C. Verrelli1, 2 and Sarah A. Tishkoff1, 
, 
1 Department of Biology, University of Maryland, College Park
2 Center for Evolutionary Functional Genomics, The Biodesign Institute, Arizona State University, Tempe
Address for correspondence and reprints: Dr. Sarah Tishkoff, Department of Biology, University of Maryland, College Park, MD 20742Abstract
Trichromatic color vision in humans results from the combination of red, green, and blue photopigment opsins. Although color vision genes have been the targets of active molecular and psychophysical research on color vision abnormalities, little is known about patterns of normal genetic variation in these genes among global human populations. The current study presents nucleotide sequence analyses and tests of neutrality for a 5.5-kb region of the X-linked long-wave “red” opsin gene (OPN1LW) in 236 individuals from ethnically diverse human populations. Our analysis of the recombination landscape across OPN1LW reveals an unusual haplotype structure associated with amino acid replacement variation in exon 3 that is consistent with gene conversion. Compared with the absence of OPN1LW amino acid replacement fixation since divergence from chimpanzee, the human population exhibits a significant excess of high-frequency OPN1LW replacements. Our results suggest that subtle changes in L-cone opsin wavelength absorption may have been adaptive during human evolution.
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