Adaptive divergence of a transcriptional enhancer between populations of Drosophila melanogaster
Adaptive divergence of a transcriptional enhancer between populations of Drosophila melanogaster
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DOI：
10.1098/rstb.2013.0024
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发表时间：
2013-12-19
影响因子：
6.3
通讯作者：
Parsch, John
中科院分区：
文献类型：
--
作者：
Glaser-Schmitt, Amanda;Catalan, Ana;Parsch, John
随着物种在新的栖息地定居，它们必须适应当地的环境。这种适应很大程度上被认为是在调节水平上发生的；然而，人们对遗传多态、表达变异和适应之间的关系知之甚少。黑腹果蝇大约在15000年前从撒哈拉以南非洲的祖先范围扩展而来，是研究调控进化的一个极好的模式系统。在这里，我们关注的是CG9509基因，它在非洲和欧洲的黑腹夜蛾群体中的表达有所不同。表达差异是由CG9509编码序列附近的转录增强子内的变异引起的。序列变异模式表明，该增强子是最近正选择的目标，这表明表达差异是适应性的。对来自欧洲、亚洲、北非和撒哈拉以南非洲的新人群样本中CG9509增强子的分析表明，在祖先范围之外，序列多态大大减少。在撒哈拉以南非洲没有的衍生单倍型在所有其他人群中都很常见。这些观察结果与伴随着物种范围扩大的选择性扫描是一致的。新的数据有助于确定导致增强子活性差异的序列变化。
As species colonize new habitats they must adapt to the local environment. Much of this adaptation is thought to occur at the regulatory level; however, the relationships among genetic polymorphism, expression variation and adaptation are poorly understood. Drosophila melanogaster, which expanded from an ancestral range in sub-Saharan Africa around 15 000 years ago, represents an excellent model system for studying regulatory evolution. Here, we focus on the gene CG9509, which differs in expression between an African and a European population of D. melanogaster. The expression difference is caused by variation within a transcriptional enhancer adjacent to the CG9509 coding sequence. Patterns of sequence variation indicate that this enhancer was the target of recent positive selection, suggesting that the expression difference is adaptive. Analysis of the CG9509 enhancer in new population samples from Europe, Asia, northern Africa and sub-Saharan Africa revealed that sequence polymorphism is greatly reduced outside the ancestral range. A derived haplotype absent in sub-Saharan Africa is at high frequency in all other populations. These observations are consistent with a selective sweep accompanying the range expansion of the species. The new data help identify the sequence changes responsible for the difference in enhancer activity.