cis-Regulatory Changes in Kit Ligand Expression and Parallel Evolution of Pigmentation in Sticklebacks and Humans

HHMI and Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Cell (Impact Factor: 32.24). 01/2008; 131(6):1179-89. DOI: 10.1016/j.cell.2007.10.055
Source: PubMed


Dramatic pigmentation changes have evolved within most vertebrate groups, including fish and humans. Here we use genetic crosses in sticklebacks to investigate the parallel origin of pigmentation changes in natural populations. High-resolution mapping and expression experiments show that light gills and light ventrums map to a divergent regulatory allele of the Kit ligand (Kitlg) gene. The divergent allele reduces expression in gill and skin tissue and is shared by multiple derived freshwater populations with reduced pigmentation. In humans, Europeans and East Asians also share derived alleles at the KITLG locus. Strong signatures of selection map to regulatory regions surrounding the gene, and admixture mapping shows that the KITLG genomic region has a significant effect on human skin color. These experiments suggest that regulatory changes in Kitlg contribute to natural variation in vertebrate pigmentation, and that similar genetic mechanisms may underlie rapid evolutionary change in fish and humans.

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    • "The revised genome assembly provides a more accurate understanding of the structure of the stickleback genome, which should aid efforts to map genes controlling stickleback phenotypes and understand genomic dynamics during stickleback evolution. The genetic mapping of distinct QTL controlling gill raker length in two crosses illustrates that, in contrast to several prominent cases in sticklebacks (Chan et al. 2010; Colosimo et al. 2005; Miller et al. 2007 "
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    G3-Genes Genomes Genetics 06/2015; 5(7). DOI:10.1534/g3.115.017905 · 3.20 Impact Factor
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    • "Melanocytes are the only chromatophore type found within birds and mammals (Mills and Patterson, 2009), determining the color of feathers, furs, and skin (Lin and Fisher, 2007). The diversity of pigment pattern found within higher vertebrates is generated due to different contributions of the 2 types of melanin (Mills and Patterson, 2009), mutations within the pigment synthesizing pathway and/or proper pigment cell development (Miller et al., 2007). In contrast, lower vertebrates and invertebrates often possess more than one pigment cell type. "
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    • "Sticklebacks fall prey to a wide variety of predators, such as aquatic bird, insect, and larger fish species, due to their small size, and thus they have a suite of morphological and behavioral adaptations that defend themselves against predators (Huntingford and Coyle 2007). Sticklebacks exhibit dark coloration particularly in dorsolateral surfaces, which is determined by melanin level and melanophore number, and interestingly both freshwater and marine sticklebacks show striking among-and within-population variations in the amount and pattern of the dark pigmentation (Miller et al. 2007; Greenwood et al. 2011, 2012). These differences are probably associated with ecological differences, particularly in predation pressure, because melanin coloration (brown, gray, and black) against dark background color of river bed or aquatic plants provides crypsis (Price et al. 2008). "
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