A scan for signatures of positive selection in candidate loci for skin pigmentation in humans
A scan for signatures of positive selection in candidate loci for skin pigmentation in humans
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DOI：
10.1093/molbev/msl030
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发表时间：
2006-09-01
影响因子：
10.7
通讯作者：
Alonso, Santos
中科院分区：
文献类型：
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作者：
Izagirre, Neskuts;Garcia, Iker;Alonso, Santos
尽管苍白的皮肤和强烈的阳光暴晒对个体造成了重要的健康风险，但在人群水平上，这种风险是否具有进化意义还不太清楚。从这个意义上讲，人们提出了许多适应性假说来解释人类皮肤色素沉着的进化，如对阳光致癌的光保护、性别选择、维生素D合成或耐光性化合物的光保护等。预计如果皮肤色素沉着是适应性的，我们可能能够在一些相关基因上看到正选择的特征。为了检测这一特征，我们通过系统发育和群体遗传学测试分析了一组81个候选基因座。我们的结果表明，明皮肤和暗皮肤都可能具有适应价值。在表现这一特征的主要基因座中，TP53BP1显示了非洲人适应性选择的明显证据，而TYRP1和SLC24A5则显示了高加索人适应性选择的证据。尽管我们无法提供一种基于这些基因的机制来解释浅色皮肤的优势，但如果TP53BP1，也许还有Rad50，确实赋予了被分析的非洲人一种适应价值，那么光保护对阳光诱导的皮肤损伤/癌症的保护可能被认为是推动人类皮肤色素沉着进化的一种机制。
Although the combination of pale skin and intense sun exposure results in an important health risk for the individual, it is less clear if at the population level this risk has possessed an evolutionary meaning. In this sense, a number of adaptive hypotheses have been put forward to explain the evolution of human skin pigmentation, such as photoprotection against sun-induced cancer, sexual selection, vitamin D synthesis or photoprotection of photolabile compounds, among others. It is expected that if skin pigmentation is adaptive, we might be able to see the signature of positive selection on some of the genes involved. In order to detect this signature, we analyze a battery of 81 candidate loci by means of phylogenetic and population genetic tests. Our results indicate that both light and dark skin may possess adaptive value. Of the main loci presenting this signature, TP53BP1 shows clear evidence of adaptive selection in Africans, whereas TYRP1 and SLC24A5 show evidence of adaptive selection in Caucasians. Although we cannot offer a mechanism that based on these genes explains the advantage of light skin, if TP53BP1, and perhaps RAD50, have truly conferred an adaptive value to the African population analyzed, photoprotection against sun-induced skin damage/cancer might be proposed as a mechanism that has driven the evolution of human skin pigmentation.