Data from: Approximate Bayesian computation reveals the crucial role of oceanic islands for the assembly of continental biodiversity

The perceived low levels of genetic diversity, poor interspecific competitive and defensive ability, and loss of dispersal capacities of insular lineages have driven the view that oceanic islands are evolutionary dead ends. Focusing on the Atlantic bryophyte flora distributed across the archipelagos of the Azores, Madeira, the Canary Islands, Western Europe, and northwestern Africa, we used an integrative approach with species distribution modeling and population genetic analyses based on approximate Bayesian computation to determine whether this view applies to organisms with inherent high dispersal capacities. Genetic diversity was found to be higher in island than in continental populations, contributing to mounting evidence that, contrary to theoretical expectations, island populations are not necessarily genetically depauperate. Patterns of genetic variation among island and continental populations consistently fitted those simulated under a scenario of de novo foundation of continental populations from insular ancestors better than those expected if islands would represent a sink or a refugium of continental biodiversity. We, suggest that the northeastern Atlantic archipelagos have played a key role as a stepping stone for transoceanic migrants. Our results challenge the traditional notion that oceanic islands are the end of the colonization road and illustrate the significant role of oceanic islands as reservoirs of novel biodiversity for the assembly of continental floras.长期以来，学界因岛屿支系普遍存在遗传多样性水平偏低、种间竞争与防御能力孱弱以及扩散能力丧失等特征，形成了大洋岛屿属于进化死端的观点。本研究聚焦分布于亚速尔群岛、马德拉群岛、加那利群岛、西欧及西北非的大西洋苔藓植物区系，整合物种分布模型与基于近似贝叶斯计算（Approximate Bayesian Computation）的种群遗传分析方法，旨在验证该观点是否适用于本身具备高扩散能力的生物类群。研究发现岛屿种群的遗传多样性高于大陆种群，这为越来越多的相关证据提供了新支撑：与理论预期相悖，岛屿种群未必存在遗传多样性匮乏的问题。岛屿与大陆种群间的遗传变异模式，与“大陆种群由岛屿祖先类群全新奠基形成”的模拟场景高度吻合，其契合度远高于“岛屿作为大陆生物多样性的种群汇或避难所”的预期模式。本研究认为，东北大西洋群岛在跨洋迁移生物的扩散过程中发挥了关键的踏脚石作用。本研究结果挑战了“大洋岛屿是定殖路径终点”的传统观点，并揭示了大洋岛屿作为新生物多样性储库，在大陆植物区系构建过程中发挥的重要作用。