Data from: Passive rafting is a powerful driver of transoceanic gene flow

Dispersal by passive oceanic rafting is considered important for the assembly of biotic communities on islands. However, not much is known about levels of population genetic connectivity maintained by rafting over transoceanic distances. We assess the evolutionary impact of kelp-rafting by estimating population genetic differentiation in three kelp-associated invertebrate species across a system of islands isolated by oceanic gaps for over 5 million years, using mtDNA and AFLP markers. The species occur throughout New Zealand's subantarctic islands, but lack pelagic stages and any opportunity for anthropogenic transportation, and hence must rely on passive rafting for long-distance dispersal. They all have been directly observed to survive transoceanic kelp-rafting journeys in this region. Our analyses indicate that regular gene flow occurs among populations of all three species between all of the islands, especially those on either side of the subtropical front oceanographic boundary. Notwithstanding its perceived sporadic nature, long-distance kelp-rafting appears to enable significant gene flow among island populations separated by hundreds of kilometres of open ocean.被动海洋筏运被认为对岛屿生物群落的组装具有关键作用。然而，学界对跨洋距离下筏运所维持的种群遗传连通性水平仍知之甚少。本研究借助线粒体DNA（mtDNA）与扩增片段长度多态性标记（AFLP markers），对被开阔海洋隔离超500万年的岛屿群中的3种海藻伴生无脊椎动物物种开展种群遗传分化评估，以此研判海藻筏运的演化影响。该类物种广泛分布于新西兰亚南极群岛，既无浮游阶段，也无任何人为运输的可能，因此远距离扩散只能依赖被动筏运。此前已有研究直接观察到它们可在本区域完成跨洋海藻筏运旅程并存活。分析结果显示，3个物种种群在所有岛屿间均存在常规基因流，尤以亚热带锋面海洋学边界两侧的岛屿种群间最为显著。尽管长期以来人们认为长距离海藻筏运具有偶发性，但该过程似乎能够在被数百公里开阔海洋分隔的岛屿种群间实现显著的基因交流。