Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, A-1210, Vienna, Austria.
Mol Ecol. 2012 Oct;21(19):4748-69. doi: 10.1111/j.1365-294X.2012.05731.x. Epub 2012 Aug 22.
Understanding the genetic underpinnings of adaptive change is a fundamental but largely unresolved problem in evolutionary biology. Drosophila melanogaster, an ancestrally tropical insect that has spread to temperate regions and become cosmopolitan, offers a powerful opportunity for identifying the molecular polymorphisms underlying clinal adaptation. Here, we use genome-wide next-generation sequencing of DNA pools ('pool-seq') from three populations collected along the North American east coast to examine patterns of latitudinal differentiation. Comparing the genomes of these populations is particularly interesting since they exhibit clinal variation in a number of important life history traits. We find extensive latitudinal differentiation, with many of the most strongly differentiated genes involved in major functional pathways such as the insulin/TOR, ecdysone, torso, EGFR, TGFβ/BMP, JAK/STAT, immunity and circadian rhythm pathways. We observe particularly strong differentiation on chromosome 3R, especially within the cosmopolitan inversion In(3R)Payne, which contains a large number of clinally varying genes. While much of the differentiation might be driven by clinal differences in the frequency of In(3R)P, we also identify genes that are likely independent of this inversion. Our results provide genome-wide evidence consistent with pervasive spatially variable selection acting on numerous loci and pathways along the well-known North American cline, with many candidates implicated in life history regulation and exhibiting parallel differentiation along the previously investigated Australian cline.
理解适应性进化的遗传基础是进化生物学中的一个基本但尚未解决的问题。黑腹果蝇是一种起源于热带的昆虫，已经扩散到温带地区并分布于全球，为鉴定导致地理渐变适应的分子多态性提供了有力的机会。在这里，我们使用来自北美东海岸三个种群的 DNA 池的全基因组下一代测序（pool-seq），研究纬度分化的模式。比较这些种群的基因组特别有趣，因为它们在许多重要的生活史特征上表现出地理渐变。我们发现广泛的纬度分化，许多分化最强的基因涉及主要功能途径，如胰岛素/TOR、蜕皮激素、torso、EGFR、TGFβ/BMP、JAK/STAT、免疫和生物钟途径。我们在 3R 染色体上观察到特别强烈的分化，尤其是在世界性的倒位 In(3R)Payne 内，其中包含大量地理渐变的基因。虽然分化的大部分可能是由 In(3R)P 频率的地理差异驱动的，但我们也鉴定了一些可能与这个倒位无关的基因。我们的结果提供了全基因组证据，一致表明在著名的北美渐变线上，许多基因座和途径受到普遍的空间可变选择的影响，许多候选基因与生活史调控有关，并沿着以前研究过的澳大利亚渐变线表现出平行分化。
