Lichens are highly successful and stable mutualistic associations between fungi and either or both green algae and cyanobacteria. Although the cosmopolitan genus Peltigera is one of the earliest described lichens, due to its great abundance in nature and prominent morphological features, its morphological variation has been puzzling taxonomists since its discovery. This diverse genus of approximately 90 species is ecologically important in part because its cyanobacterial partner fixes atmospheric nitrogen. Despite the obligate nature of the lichen symbiosis, nearly all revisionary studies of lichens have been restricted to the fungus. Here, for the first time, the two main symbiotic partners will be characterized genetically. This will be the first worldwide phylogenetic study of Peltigera. It will provide a framework for detailed taxonomic revisions of three species complexes, which will lead to the description of at least ten new species in North America alone, and will drastically improve the highly inconsistent delimitation of existing species. This study will also demonstrate the role cyanobacteria can play in shaping evolutionary histories of fungi and vice versa.
In addition to the training of one postdoctoral researcher and one undergraduate student each year, two high school students will be introduced to conducting research on symbiotic systems. The resulting keys for the identification of Peltigera species will improve the quality of research in the fields of ecology, conservation biology and fungal systematics. This revisionary work will bring together all leading experts working on Peltigera by forming a strong international network.
