入侵物种是全球生物多样性的主要威胁之一,在海洋生态系统中,金枪鱼有一些突出的例子。Styelaplicata是一种海鞘物种,居住在所有温带海洋的港口,因此被认为是一个繁荣的入侵物种。然而,这个物种的适应机制,介绍历史,人口结构从未完全阐明。这里,通过基因分型87S.来自全球18个地区的plicata个体使用2b-RADseq,我们确认了四个染色体倒转的整体存在,展示了这个物种的种群结构,检测本地自适应信号,并推断历史人口事件。我们表明北卡罗来纳州的个体构成了一个无关的群体,大西洋-地中海和太平洋地区形成了自己的具有子结构的遗传集群,是大西洋北部和南部地区之间最明显的分裂。南卡罗来纳州的地区在北卡罗来纳州和其他两个群体之间存在中间遗传位置,指向具有反复基因流的杂种起源。我们生成并测试人口统计模型,提供了大西洋和太平洋两个独立引入事件的证据,和起源于南卡罗来纳州人口的混合物。最后,我们确定适应的候选基因座,与细胞过程有关的功能,新陈代谢,发展,和离子传输,在其他人中。总的来说,这项研究强调了plicata的复杂历史过程,这导致了这个物种目前的分布,人口结构,以及全球海洋中的局部适应足迹。
Invasive species are one of the main threats to global biodiversity and, within marine ecosystems, tunicates feature some prominent examples. Styela plicata is an ascidian species inhabiting harbours in all temperate oceans and seas, thus being considered a thriving invasive species. However, this species\' adaptive mechanisms, introduction history, and population structure have never been completely elucidated. Here, by genotyping 87 S. plicata individuals from 18 localities worldwide with 2b-RADseq, we confirm the global presence of four chromosome inversions, demonstrate population structuring on this species, detect local adaptation signals, and infer historical demographic events. We show that North Carolina individuals constitute an unrelated population, Atlanto-Mediterranean and Pacific localities form their own genetic clusters with substructuring, being the most evident the split between northern and southern Atlantic localities. The locality of South Carolina presents an intermediate genetic position between North Carolina and the other two groups pointing to a hybrid origin with recurrent gene flow. We generate and test demographic models, providing evidence of two independent introduction events to the Atlantic and Pacific, and an admixture that originated the population of South Carolina. Finally, we identify candidate loci for adaptation, with functions involved with cell processes, metabolism, development, and ion transport, among others. Overall, this study highlights the complex historical processes of S. plicata, which have led this species to its current distribution, population structure, and local adaptation footprint in oceans worldwide.