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.挪威中部寒温带雨林是全球纬度最高的雨林，其内附生地衣物种多样性极为丰富。这类雨林残遗斑块分布于沟壑系统中，皆伐作业使得剩余斑块间的距离显著增加。我们据此提出假说：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的流失。为验证该假说，我们选取8个简单序列重复（Simple Sequence Repeats, SSR）位点，对三分地衣肺衣（Lobaria pulmonaria）的种群遗传多样性与遗传结构展开了评估。我们在三个采样点采集了欧洲云杉（Picea abies）枝条上生长的地衣叶状体，以及积雪中沉积的地衣繁殖体。与预期结果相反，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。同时，种群间的遗传分化程度有限，历史迁移率较高，且估算得到较高比例的第一代迁入个体，这表明距离小于30公里的林斑之间存在较高的连通性。几乎所有的遗传变异均来自样点内部，种群内的空间遗传结构要么不存在，要么仅在5–10米的小尺度上显现。剩余寒温带老龄雨林中较高的遗传多样性表明，即便残遗林斑也可作为遗传多样性保护的适宜生境。