Cicconardi Francesco, Marcatili Paolo, Arthofer Wolfgang, Schlick-Steiner Birgit C, Steiner Florian M
Institute of Ecology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
Center for Biological Sequence Analysis, Technical University of Denmark, Kgs. Lyngby, Denmark.
Mol Phylogenet Evol. 2017 Jul;112:230-243. doi: 10.1016/j.ympev.2017.04.023. Epub 2017 Apr 27.
The growing genomic information on non-model organisms eases exploring the evolutionary history of biodiversity. This is particularly true for Drosophila flies, in which the number of sequenced species doubled recently. Because of its outstanding diversity of species, Drosophila has become one of the most important systems to study adaptive radiation. In this study, we performed a genome-wide analysis of positive diversifying selection on more than 2000 single-copy orthologous groups in 25 species using a recent method of increased accuracy for detecting positive diversifying selection. Adopting this novel approach enabled us to find a consistent selection signal throughout the genus Drosophila, and a total of 1342 single-copy orthologous groups were identified with a putative signal of positive diversifying selection, corresponding to 1.9% of all loci. Specifically, in lineages leading to D. grimshawi, a strong putative signal of positive diversifying selection was found related to cell, morphological, neuronal, and sensorial development and function. A recurrent signal of positive diversifying selection was found on genes related to aging and lifespan, suggesting that selection had shaped lifespan diversity in Drosophila, including extreme longevity. Our study, one of the largest and most comprehensive ones on genome-wide positive diversifying selection to date, shows that positive diversifying selection has promoted species-specific differentiation among evolutionary lineages throughout the Drosophila radiation. Acting on the same biological processes via different routes, positive diversifying selection has promoted diversity of functions and adaptive divergence.
关于非模式生物不断增长的基因组信息，便于探索生物多样性的进化历史。果蝇尤其如此，其测序物种的数量最近翻了一番。由于果蝇具有突出的物种多样性，它已成为研究适应性辐射的最重要系统之一。在本研究中，我们使用一种提高了检测正趋异选择准确性的最新方法，对25个物种中2000多个单拷贝直系同源基因进行了全基因组范围的正趋异选择分析。采用这种新方法使我们能够在整个果蝇属中找到一致的选择信号，总共鉴定出1342个单拷贝直系同源基因具有正趋异选择的假定信号，占所有基因座的1.9%。具体而言，在导致格氏果蝇的谱系中，发现了与细胞、形态、神经元和感官发育及功能相关的强烈正趋异选择假定信号。在与衰老和寿命相关的基因上发现了反复出现的正趋异选择信号，这表明选择塑造了果蝇的寿命多样性，包括极长的寿命。我们的研究是迄今为止关于全基因组正趋异选择最大且最全面的研究之一，表明正趋异选择在整个果蝇辐射的进化谱系中促进了物种特异性分化。通过不同途径作用于相同的生物学过程，正趋异选择促进了功能多样性和适应性分化。
