The Timing of Pigmentation Lightening in Europeans
The Timing of Pigmentation Lightening in Europeans
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DOI：
10.1093/molbev/mss207
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发表时间：
2013-01-01
影响因子：
10.7
通讯作者：
Rocha, Jorge
中科院分区：
文献类型：
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作者：
Beleza, Sandra;Santos, Antonio M.;Rocha, Jorge
在人类人群中观察到的皮肤色素沉着与纬度之间的负相关被认为是由选择压力形成的，在远离赤道的地区，人们倾向于浅色皮肤，以促进维生素D的合成。皮肤色素沉着的几个候选基因已经显示出与肤色的地理空间变异重叠的多态性模式。然而，很少有工作集中在估计皮肤色素沉着发生变化的时间框架以及作用于不同色素沉着基因的选择强度上。为了为浅色色素的进化提供一个时间框架，我们使用前向蒙特卡罗模拟结合拒绝抽样算法来估计欧洲人与该性状相关的四个基因（KITLG、TYRP1、SLC24A5和SLC45A2）的选择性扫描开始时间和选择系数。利用与每个基因的单核苷酸多态性相关的快速进化的微卫星组成的复合单倍型系统，我们估计欧洲人和东亚人在KITLG共有的扫描开始于大约3万年前，在非洲外迁移之后，而欧洲特异性等位基因TYRP1， SLC24A5和SLC45A2的选择性扫描开始得更晚，在最近的11,000-19,000年。早在现代人类第一次迁徙到欧洲之后。我们认为，这些模式受到最近人类种群规模增加的影响，这有利于在不同位点积累优势变异。
The inverse correlation between skin pigmentation and latitude observed in human populations is thought to have been shaped by selective pressures favoring lighter skin to facilitate vitamin D synthesis in regions far from the equator. Several candidate genes for skin pigmentation have been shown to exhibit patterns of polymorphism that overlap the geospatial variation in skin color. However, little work has focused on estimating the time frame over which skin pigmentation has changed and on the intensity of selection acting on different pigmentation genes. To provide a temporal framework for the evolution of lighter pigmentation, we used forward Monte Carlo simulations coupled with a rejection sampling algorithm to estimate the time of onset of selective sweeps and selection coefficients at four genes associated with this trait in Europeans: KITLG, TYRP1, SLC24A5, and SLC45A2. Using compound haplotype systems consisting of rapidly evolving microsatellites linked to one single-nucleotide polymorphism in each gene, we estimate that the onset of the sweep shared by Europeans and East Asians at KITLG occurred approximately 30,000 years ago, after the out-of-Africa migration, whereas the selective sweeps for the European-specific alleles at TYRP1, SLC24A5, and SLC45A2 started much later, within the last 11,000-19,000 years, well after the first migrations of modern humans into Europe. We suggest that these patterns were influenced by recent increases in size of human populations, which favored the accumulation of advantageous variants at different loci.