Hidden reservoirs of biological diversity - geobiology of unexplored endolithic communities associated with lichens

There is a large visible biological diversity on the surface of our planet, but it is less known that there are hidden reservoirs of biological diversity underneath the surface. Even if this subsurface biosphere is estimated to have a biomass of similar m agnitude as that of the surface biosphere, the compositions and dynamics of these communities are largely unexplored. Published data on endolithic communities have mainly focused on either the microbial or the fungal diversity in rocks. As nearly all expo sed rock surfaces, at least in northern temperate and arctic Europe, are covered by lichens, the lichen-mineral interface has been especially well investigated. Resent studies indicate that the lichen-rock interface constitutes species from more than just the fungal kingdom; it is a small ecosystem of bacteria, fungi (lichenized and non-lichenized), and algae. However, little is known about the entire biological diversity in these communities. The subsurface distribution of organisms may, in part, be co ntrolled by the mineralogy and by the ability of an organism to take advantage of mineral-bound nutrients. The proposed research project will be the first to assess the extent of the entire biological diversity in exposed terrestrial lichen covered rocks, and analyse the interaction between this endolithic biosphere and the geosphere. Molecular markers will be used to study these endolithic communities, petrographical and geochemical techniques will be used to characterise the related geosphere, while sta tistical methods will be used to analyse the interaction between the biosphere and the geosphere. Knowledge about these communities is important for a better understanding of biogeochemical processes, the mini-ecosystem lichens, the ecology of microbes, for our global genetic resources, for biotechnology, for our understanding of the origin of life on earth, as well as an important target for the search for life elsewhere in the Solar System.