Data from: Extensive gene flow over Europe and possible speciation over Eurasia in the ectomycorrhizal basidiomycete Laccaria amethystina complex.

Biogeographic patterns and large-scale genetic structure have been little studied in ectomycorrhizal fungi, despite the ecological and economic importance of ectomycorrhizal symbioses. We coupled population genetics and phylogenetic approaches to understand spatial structure in fungal populations on a continental scale. Using 9 microsatellite markers, we characterised gene flow among 16 populations of the widespread ectomycorrhizal basidiomycete Laccaria amethystina over Europe (over 2900km). We also widened our scope to two additional populations from Japan (104 km away), and compared them with European populations through microsatellite markers and multi-locus phylogenies, using 3 nuclear genes (NAR, G6PD and ribosomal DNA) and two mitochondrial ribosomal genes. European L. amethystina populations displayed limited differentiation (average FST=0.041) and very weak isolation by distance. This panmictic European pattern may result from effective aerial dispersal of spores, high genetic diversity in populations, and mutualistic interactions with multiple hosts that all facilitate migration. The multi-locus phylogeny based on nuclear genes confirmed that Japanese and European specimens were closely related but clustered on a geographical basis. By using microsatellite markers, we found that Japanese populations were strongly differentiated from the European populations (FST=0.416), more than expected by extrapolating the European pattern of isolation by distance. Population structure analyses clearly separated the populations into two clusters, European and Japanese clusters. We discuss the possibility of isolation by distance in a continuous population (considering some evidence for a ring species over the Northern Hemisphere) versus an allopatric speciation over Eurasia, making L. amethystina a promising model of intercontinental species for future studies.

尽管外生菌根共生（ectomycorrhizal symbioses）在生态与经济层面具有重要价值，但学界对外生菌根真菌（ectomycorrhizal fungi）的生物地理格局及大尺度遗传结构的研究仍相对匮乏。本研究结合群体遗传学与系统发育分析方法，旨在解析大陆尺度下真菌种群的空间结构。我们利用9个微卫星标记（microsatellite markers），对覆盖超2900公里的欧洲范围内广泛分布的外生菌根担子菌（basidiomycete）紫晶蜡蘑（Laccaria amethystina）的16个种群间的基因流进行了表征。此外，我们将研究范围拓展至日本的2个额外种群（两地间距104公里），并通过微卫星标记结合多位点系统发育分析，以3个核基因（NAR、G6PD及核糖体DNA）与2个线粒体核糖体基因作为分子标记，将其与欧洲种群进行比对。欧洲紫晶蜡蘑种群表现出有限的遗传分化（平均FST=0.041），且距离隔离效应极弱。这种泛交的欧洲种群格局，可能源于孢子高效的气传扩散、种群内较高的遗传多样性，以及与多种宿主的互利共生相互作用——这些因素均能促进种群迁移。基于核基因构建的多位点系统发育树证实，日本与欧洲的标本亲缘关系密切，但呈现出地理聚类的特征。通过微卫星标记分析，我们发现日本种群与欧洲种群间存在显著的遗传分化（FST=0.416），其分化程度远超基于欧洲距离隔离格局外推所得的预期值。种群结构分析明确将所有种群划分为两个聚类簇：欧洲种群簇与日本种群簇。我们讨论了两种演化假说：一是连续种群中的距离隔离（结合北半球存在环物种的相关证据），二是欧亚大陆的异域成种过程，这使得紫晶蜡蘑成为未来跨大陆物种研究的极具潜力的模式体系。