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.

挪威中部寒带雨林是全球纬度最高的雨林，其内附生地衣拥有极高的多样性。这些雨林残遗斑块分布于沟谷系统中，皆伐作业使得剩余斑块间的距离显著增加。本研究假设：剩余林分中规模相对较小的地衣种群，因瓶颈效应（bottlenecks）与奠基者效应（founder events）出现了遗传多样性丧失。为验证该假设，本研究以8个简单序列重复（Simple Sequence Repeat，SSR）位点为分子标记，对三组分地衣肺衣（Lobaria pulmonaria）的种群遗传多样性与遗传结构进行了评估。研究人员在3个采样点，分别采集了生长在欧洲云杉（Picea abies）枝条上的地衣叶状体以及积雪中沉积的地衣繁殖体。与预期相反，本研究在地衣样本与积雪样本中均检测到了高水平的遗传多样性，且研究种群的有效种群规模较高。此外，种群间的遗传分化程度较低，历史迁移率较高，且估算得到的第一代移民占比颇高，这表明30公里以内的种群间存在较高的连通性。几乎所有的遗传变异均来自种群内部；种群内的空间遗传结构要么不存在，要么仅在小尺度（5–10米）范围内显现。剩余寒带老龄雨林中仍保有高水平的遗传多样性，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。