Data from: Landscape and oceanic barriers shape dispersal and population structure in the island nematode, Pristionchus pacificus

Despite the biological importance and diversity of nematodes, little is known of the factors influencing their dispersal and shaping their evolutionary history. Populations of the cosmopolitan species Pristionchus pacificus are characterized by high genetic diversity and strong spatial structure, which contrasts with patterns detected in nematode species such as Caenorhabditis elegans. The environmentally heterogeneous volcanic Mascarene Islands provide an ideal setting for investigating fine-scale patterns of nematode migration and gene flow. Based on the analysis of data from 19 nuclear microsatellites and one mitochondrial marker, we infer support for the colonization of both La Réunion Island and Mauritius from similar multiple geographical sources. Although the long-term persistence of populations on both islands is well supported, the historical colonization of one island from the other cannot be discounted. In fact, periodic, bi-directional migration between the islands following their initial colonization is strongly supported in isolation with migration analyses, supporting the occurrence of rare trans-oceanic dispersal events in P. pacificus. Through a combination of population and landscape genetic analyses we also infer non-uniform dispersal across the landscape on the island of La Réunion, probably mediated by the movements of beetle hosts. Collectively, we show that gene flow in P. pacificus is limited by environmental and oceanic barriers, and shaped by the intricacies of the nematode–beetle host interaction

尽管线虫在生物学上具有重要意义且类群多样，但目前学界对影响其扩散、塑造其演化历史的相关因子仍知之甚少。广布种太平洋拟杆线虫（Pristionchus pacificus）的种群具有高遗传多样性与显著的空间结构特征，这与秀丽隐杆线虫（Caenorhabditis elegans）等线虫类群的检测模式形成鲜明对比。环境异质性显著的火山群岛——马斯卡林群岛（Mascarene Islands）为研究线虫迁移与基因流的精细尺度模式提供了理想的研究场景。本研究基于19个核微卫星（nuclear microsatellites）与1个线粒体标记（mitochondrial marker）的数据开展分析，推断留尼汪岛（La Réunion Island）与毛里求斯（Mauritius）的种群均起源于相似的多个地理源种群。尽管两类岛屿种群的长期存续得到了充分支持，但二者之间存在一方起源于另一方的历史定殖事件的可能性仍无法排除。事实上，通过隔离-迁移分析，研究结果强烈支持在初始定殖后两岛之间存在周期性的双向迁移，这证明了太平洋拟杆线虫存在罕见的跨洋扩散事件。结合群体遗传学与景观遗传学分析，本研究还推断留尼汪岛的线虫扩散在景观尺度上并不均匀，这一过程可能由甲虫宿主的移动所介导。综上，本研究证实太平洋拟杆线虫的基因流受到环境与海洋屏障的限制，并由线虫与甲虫宿主之间复杂的互作关系所塑造。