多种生物在迁移到新的生存环境并不断适应的过程中会进化出不同的色素沉积方式。在12月14日出版的《细胞》（Cell）上，来自美国、葡萄牙和加拿大的科学家发现，三刺鱼（threespine stickleback）体内干细胞因子基因Kit ligand的改变与其身体颜色变化有关，三刺鱼在上一次冰河期末期迁移到新的淡水环境中。而现代人类在过去5万年间也不断拓展生存环境，科学家表示，Kit ligand基因同样对不同人种的肤色进化起到了作用。
最近，很多研究表明，特定的基因可能被不同生物利用，从而进化出类似的表型。尽管科学家对于这种现象的内在遗传学机制很感兴趣，但是很难找到合适的研究对象。而三刺鱼是一种分析脊椎动物进化的基因基础的强大工具。之前大部分针对三刺鱼的基因定位研究主要针对骨骼结构和体型，然而色素变化是进行不同物种间比较研究的合适显型。
三刺鱼和人类在从原始环境中迁移到新的生存环境中时，都会发生色素沉积的进化改变。三刺鱼拥有黑色、杂色或白色的体色，而人类的皮肤颜色与纬度相关。尽管存在多种针对鱼类和人类色素变化的假设，但是其内在的基因机制并不清楚。
在最新的研究中，科学家使用了全基因组定位技术分析了三刺鱼色素沉积进化的基因基础，然后用混合定位方法研究了造成三刺鱼这种色素变化的基因因子，是否同样与人类进化过程中表现出的色素变化相关。
结果表明，不同生物表型的迅速变化或许拥有同样的内在机制。科学家认为，研究不同生物的其它形态、生理和行为差异进化是否存在类似的基因学机制将会是一件很有趣的工作。（科学网 何宏辉/编译）
原始出处:
Cell, Vol 131, 1179-1189, 14 December 2007
Article
cis-Regulatory Changes in Kit Ligand Expression and Parallel Evolution of Pigmentation in Sticklebacks and Humans
Craig T. Miller,1 Sandra Beleza,2 Alex A. Pollen,1 Dolph Schluter,3 Rick A. Kittles,4 Mark D. Shriver,5 and David M. Kingsley1,
1 HHMI and Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
2 Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4250-400 Porto, Portugal
3 Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
4 Department of Medicine, Section of Genetic Medicine, The University of Chicago, Chicago, IL 60637, USA
5 Department of Anthropology, The Pennsylvania State University, University Park, PA 16802, USA
Corresponding author
David M. Kingsley
kingsley@cmgm.stanford.edu
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.
