In lichen symbioses, fungal secondary metabolites provide UV protection on which lichen algae such as trebouxiophycean green algae—the most prominent group of photobionts in lichen symbioses—sensitively depend. These metabolites differ in their UV absorbance capability and solvability, and thus vary in their propensity of being leached from the lichen body in humid and warm environments, with still unknown implications for the global distribution of lichens. In this study covering more than 10,000 lichenised fungal species, we show that the occurrence of fungal-derived metabolites in combination with their UV absorbance capability and their probability of being leached in warm and humid environments are important eco-evolutionary drivers of global lichen distribution. Fungal-derived UV protection seems to represent an indirect environmental adaptation in which the lichen fungus invests to protect the trebouxiophycean photobiont from high UV radiation in warm and humid climates and, by doing this, secures its carbon source.

中文翻译：

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关键代谢物的化学性质决定了地衣的全球分布

在地衣共生体中，真菌次生代谢物提供紫外线防护，地衣藻类如海藻绿藻（地衣共生体中最突出的光生物群）敏感地依赖于紫外线防护。这些代谢物的紫外吸收能力和溶解性不同，因此它们在潮湿和温暖的环境中从地衣体内浸出的倾向也不同，对地衣的全球分布的影响仍然未知。在这项涵盖 10,000 多种地衣真菌物种的研究中，我们表明真菌衍生代谢物的出现与其紫外线吸收能力以及它们在温暖和潮湿环境中被浸出的可能性相结合，是全球地衣分布的重要生态进化驱动因素。