Data from: 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 diversification prior to these cycles and the selection of photobionts with different altitudinal distributions explain the current sympatric, but ecologically differentiated habitat partitioning of L. pulmonaria. In addition, the habitat preferences of the mycobiont are determined by other factors and are rather independent of those of the photobiont at the landscape level. The distinct gene pools should be considered evolutionarily significant units, and deserve specific conservation priorities in the future, e.g. gene pool A, which is an Pliocene relict.本研究以欧洲最大的原始山毛榉林（占地10000公顷）为研究区域，对附生树生地衣肺衣（Lobaria pulmonaria）的种群遗传学展开探究。在对该区域开展全面密集调查期间，研究团队采集了源自483棵树的1522个地衣叶状体（thallus）片段，并利用8个真菌共生体（mycobiont）特异性微卫星标记（microsatellite marker）与14个光合共生体（photobiont）特异性微卫星标记对样本进行基因分型。研究发现，肺衣的真菌共生体与光合共生体均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。该共生基因库的小尺度分布格局与海拔高度相关，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），将肺衣的两个真菌基因库的分化时间估算为更新世早期。尽管二者可能位于气候条件不同的避难所，但这两个真菌基因库均在喀尔巴阡山脉的更新世冰期循环中得以存续。冰期循环前的真菌演化分化，以及对不同海拔分布光合共生体的选择，共同解释了肺衣当前同域分布但生态分化的生境分化格局。此外，在景观尺度下，真菌共生体的生境偏好由其他因素决定，且与光合共生体的生境偏好相对独立。这两个截然不同的基因库应被视为进化显著单元（evolutionarily significant unit），未来需给予针对性的保护优先级，例如作为上新世孑遗类群的基因库A。