Microclimatic differentiation of gene pools in the Lobaria pulmonaria symbiosis in a primeval forest landscape

Population genetics of the tree-colonizing lichen Lobaria pulmonaria were studied in the largest primeval beech forest of Europe, covering 10 000 ha. During an intensive survey of the area, we collected 1522 thallus fragments originating from 483 trees, which were genotyped with 8 myco- and 14 photobiont-specific microsatellite markers. The mycobiont and photobiont of L. pulmonaria were found to consist of two distinct gene pools, which are co-existing within small areas of 3–180 ha in a homogeneous beech forest. The small-scale distribution pattern of the symbiotic gene pools was linked to altitude, and show habitat partitioning of lineages associated with either floodplains or mountain forests. Using Approximate Bayesian Computation (ABC), we dated the divergence of the two fungal gene pools of L. pulmonaria as the Early Pleistocene. Both fungal gene pools survived the Pleistocene glacial cycles in the Carpathians, though possibly in climatically different refugia. Fungal diversificat...本研究以欧洲面积达10000公顷的最大原始山毛榉林为研究区域，对附生树生地衣肺叶衣（Lobaria pulmonaria）的种群遗传学展开了探究。在对该区域开展的全面密集调查中，我们共采集了源自483棵树木的1522个地衣体片段，并利用8个真菌共生体特异性及14个光合共生体特异性微卫星标记对其进行了基因分型。研究发现，肺叶衣的真菌共生体与光合共生体各自包含两个截然不同的基因库，二者在均质山毛榉林中的3至180公顷小尺度区域内共存。共生基因库的小尺度分布格局与海拔高度相关，且呈现出与泛滥平原或山地森林相关的谱系生境分化现象。本研究借助近似贝叶斯计算（Approximate Bayesian Computation, ABC）方法，估算得到肺叶衣的两个真菌共生基因库的分化时间处于更新世早期。尽管二者所处的气候避难所可能存在差异，但这两个真菌共生基因库均在喀尔巴阡山脉的更新世冰期循环中得以存续。真菌的多样化（原文此处未完整呈现）