Data from: Genetic structure in a fragmented Northern Hemisphere rainforest: large effective sizes and high connectivity among populations of the epiphytic lichen Lobaria pulmonaria

An extraordinary diversity of epiphytic lichens is found in the boreal rainforest of central Norway, the highest-latitude rainforest in the world. These rainforest relicts are located in ravine systems, and clear cutting has increased the distance between remaining patches. We hypothesized that the relatively small lichen populations in the remaining forest stands have suffered a depletion of genetic diversity through bottlenecks and founder events. In order to test this hypothesis we assessed genetic diversity and structure in populations of the tripartite lichen Lobaria pulmonaria using eight SSR loci. We sampled thalli growing on Picea abies branches and propagules deposited in snow at three localities. Contrary to expectations, we found high genetic diversity in lichen and snow samples, and high effective sizes of the studied populations. Also, limited genetic differentiation between populations, high historical migration rates, and a high proportion of first generation immigrants were estimated, implying high connectivity across distances <30 km. Almost all genetic variation was due to variation within sites; spatial genetic structures within populations were absent or appeared on small scales (5–10 m). The high genetic diversity in the remaining old boreal rainforests shows that even relict forest patches might be suitable for conservation of genetic diversity.

全球纬度最高的雨林——挪威中部寒带雨林中，附生地衣的物种多样性极为丰富。这些雨林残遗斑块分布于沟壑系统中，皆伐作业加剧了剩余斑块间的空间隔离距离。我们提出假说：剩余林分中规模相对较小的地衣种群，因瓶颈效应与奠基者事件出现了遗传多样性丧失。为验证该假说，我们以8个简单重复序列（Simple Sequence Repeat, SSR）位点为分子标记，对肺衣（*Lobaria pulmonaria*）的种群遗传多样性与遗传结构展开评估。我们在3个采样点分别采集了欧洲云杉（*Picea abies*）枝条上生长的地衣叶状体以及积雪中沉积的繁殖体。与预期相悖的是，我们在地衣样本与积雪样本中均检测到较高的遗传多样性，且研究种群的有效种群规模较大。此外，种群间遗传分化程度有限，历史迁移率较高，且第一代移民占比可观，这表明30公里以内的空间距离下，种群间连通性极佳。几乎所有的遗传变异均来自样点内部；种群内未检测到空间遗传结构，或仅在极小尺度（5~10米）下存在空间遗传结构。剩余寒带老龄雨林中仍保有较高的遗传多样性，这表明即便只是残遗森林斑块，也可用于遗传多样性的保护工作。