Lichens colonise all regions of the earth, from the poles to the equator. They are a symbiosis of fungi and algae. Secondary metabolites, so-called “lichen substances” produced by the fungal partner play a central role to maintain this symbiosis. An interdisciplinary research team from the University of Bayreuth, the University of Hohenheim, and the Bavarian State Natural Science Collections has now discovered how different climatic conditions influence the chemical properties of lichen substances and thus the evolution and global distribution of lichens. They present their research results in „Ecology Letters“.