Data from: A worldwide phylogeography of the whiteworm lichen Thamnolia vermicularis reveals three lineages with distinct habitats and evolutionary histories

Thamnolia vermicularis is a lichenized fungus with an extremely wide distribution, being encountered in arctic and alpine environments in most continents. In this study, we used molecular markers to investigate the population structure of the fungal symbiont and the associated photosynthetic symbiotic partner of T. vermicularis. By analyzing molecular, morphological and chemical variation among 253 specimens covering the species distribution range, we revealed the existence of three mycobiont lineages. One lineage (Lineage A) is confined to the tundra region of Siberia and the Aleutian Islands, a second (Lineage B) is found in the high alpine region of the Alps and the Carpathians Mountains, and a third (Lineage C) has a worldwide distribution and also covers both the aforementioned ecosystems. Molecular dating analysis indicated that the split of the three lineages is older than the Last Glacial Maximum, but the distribution ranges and the population genetic analyses suggest an influence of last glacial period on the population structure of each lineage. We found a very low diversity of Lineage B but a higher and similar one in Lineages A and C. Demographic analyses suggested that Lineage C has its origin in the Northern Hemisphere, possibly Scandinavia, and that it has passed through a bottleneck followed by a recent population expansion. While all three lineages reproduce clonally, recombination tests suggest rare or past recombination in both lineages A and C. Moreover, our data showed that Lineage C has a comparatively low photobiont specificity, being found associated with four widespread Trebouxia lineages (three of them also shared with other lichens), while lineages A and B exclusively harbor T. simplex s. lat. Finally, we did not find support for the recognition of taxa in Thamnolia based on either morphological or chemical characters.

细枝管地衣（Thamnolia vermicularis）是一类分布范围极广的地衣型真菌，在多数大陆的北极与高山生境中均有发现。本研究采用分子标记技术，探究了该物种的真菌共生体（mycobiont）及其伴生光合共生伙伴的种群结构。本研究覆盖该物种的全分布区，对253份标本的分子、形态及化学性状变异进行分析，结果揭示了3个真菌共生体谱系的存在：谱系A（Lineage A）仅分布于西伯利亚冻原与阿留申群岛；谱系B（Lineage B）见于阿尔卑斯山脉与喀尔巴阡山脉的高海拔高山生境；谱系C（Lineage C）则为广布种，同时覆盖上述两类生境。分子定年分析显示，3个谱系的分化时间早于末次冰盛期，但分布范围与种群遗传学分析表明，末次冰期对各谱系的种群结构均产生了影响。研究发现，谱系B的遗传多样性极低，而谱系A与C的遗传多样性较高且水平相近。种群动态分析显示，谱系C起源于北半球，可能为斯堪的纳维亚地区，其种群经历了瓶颈效应后，近期发生了扩张。尽管3个谱系均以无性繁殖为主，重组检测结果显示，谱系A与C中存在罕见或曾发生过的基因重组事件。此外，本研究数据显示，谱系C的光合共生体专一性相对较低，可与4个广布的共球藻属（Trebouxia）谱系共生，其中3个谱系还可与其他地衣共生；而谱系A与B仅能共生简共球藻复合群（T. simplex s. lat.）。最终，本研究未发现支持依据形态或化学性状划分管地衣属（Thamnolia）内类群的证据。