Up to 1.5 million species of mushrooms are estimated to exist in nature. With approximately 100,000 described species, only a small fraction is currently known. A large group of mushrooms forms associations with algae and bacteria, and the resulting associations are called lichens. The delimitation of species in this group of mushrooms has been based on morphological characters. There is a growing body of evidence from molecular studies that the number of existing species in this group of mushrooms is underestimated. However, understanding the diversity of lichens is pivotal for our understanding of overall biodiversity. Lichens are important indicators for climate change, air pollution, forest health and potential sources of antibiotics and biocontrol agents. In this project the investigators will use molecular data: 1) to assess the diversity of species in a group of lichens common in North America and 2) to understand the evolution of this group of lichens.
A postdoctoral researcher will be trained and undergraduate students will participate in summer-intern programs. The PI will also participate in public lecture series and assist in developing exhibits at the Field Museum of Natural History. High school visits are designed to bring modern research into the classrooms to attract the future generation of scientists. The international nature of these collaborations will foster initiatives to develop a worldwide network of researchers. Also, results of this project will be disseminated through web sites.
Lichens are symbiotic organisms consisting of fungi and algae and/or cyanobacteria. Their diversity is not well known, so this projects aimed at testing current species delimitations, which are mainly based on morphology of the lichens and their secondary chemistry, using DNA sequence data. We have chosen the camouflage lichens (genera Melanelixia and Melaonohalea) for our studies, which are common in forest ecosystems all over North America. In addition to a dense sampling in North America, we also studied material from Europe, Asia and South America to check whether lichens with the same name occurring in these continents, really belong to the same species as the North American populations or represent distinct species. We used DNA sequence data from several loci and used different approaches to answer the questions how we can delimit species in the camouflage lichens. Our studies revealed that,, while a few species are indeed widespread and can occur in different continents, the majority of species has much more restricted geographical ranges. Within currently circumscribed species we repeatedly found so-called cryptic species, these are species that cannot not distinguished by their appearance. We were then further interested to see whether this similarity might be due to their origin. In contrast, our studies provided evidence that morphologically similar species have been separated for several million years. In some cases, we could also show that similar species have evolved from unrelated groups. This suggests that their similarity is due to convergence. Further we could demonstrate that past climatic events had an impact to the divesification in the camouflage lichens. This indicates that climatic changes had not only impact on the distribution of speies (e.g., species retracting to relict areas during glaciation) but that their diversification is also impacted by climatic changes. These results provide important data beyong systematics, since a more refined delimitation of species allows for a better understanding of diversity.
