School of Biology, University of St Andrews, St Andrews, Fife, KY16 9TH, UK.
Tree of Life, Wellcome Sanger Institute, Cambridge, CB10 1SA, UK.
Nat Commun. 2021 Jan 4;12(1):50. doi: 10.1038/s41467-020-20263-4.
Gene flow is predicted to impede parallel adaptation via de novo mutation, because it can introduce pre-existing adaptive alleles from population to population. We test this using Hawaiian crickets (Teleogryllus oceanicus) in which 'flatwing' males that lack sound-producing wing structures recently arose and spread under selection from an acoustically-orienting parasitoid. Morphometric and genetic comparisons identify distinct flatwing phenotypes in populations on three islands, localized to different loci. Nevertheless, we detect strong, recent and ongoing gene flow among the populations. Using genome scans and gene expression analysis we find that parallel evolution of flatwing on different islands is associated with shared genomic hotspots of adaptation that contain the gene doublesex, but the form of selection differs among islands and corresponds to known flatwing demographics in the wild. We thus show how parallel adaptation can occur on contemporary timescales despite gene flow, indicating that it could be less constrained than previously appreciated.
基因流预计会通过新的突变来阻碍平行适应，因为它可以将预先存在的适应性等位基因从一个种群引入到另一个种群中。我们使用夏威夷蟋蟀（Teleogryllus oceanicus）来检验这一点，在这些蟋蟀中，最近由于一种声音定向的寄生虫而选择出了缺乏发声翅膀结构的“平翅”雄性，并在这些雄性中传播。形态计量学和遗传学的比较在三个岛屿上的种群中识别出不同的平翅表型，这些表型定位于不同的基因座上。尽管如此，我们还是检测到了种群之间强烈的、近期的和正在进行的基因流。通过基因组扫描和基因表达分析，我们发现不同岛屿上平翅的平行进化与适应的共享基因组热点有关，这些热点包含基因 doublesex，但在不同岛屿上的选择形式不同，与野外已知的平翅种群动态相对应。因此，我们展示了即使存在基因流，平行适应也可以在当代时间尺度上发生，这表明它可能比以前认为的限制要小。
