Diversity of tropical lichens

2013 REU Intern Patricia Brandt


Junior Biological Sciences major at The University of Chicago

REU Mentor: Dr. Thorsten Lumbsch (Department Chair and Associate Curator, Botany)

Symposium Presentation Title: The circumscription of the genus Lecanora (Fungi: Ascomycota: Lecanoromycetes: Lecanorales)

Symposium Presentation Abstract: Classification of lichen-forming fungi has changed dramatically over the last decades with the help of molecular data. While the classification of lichenized fungi traditionally relied heavily on growth morphology and fruiting body anatomy, molecular data have often shown these characters to be of limited value to circumscribe monophyletic groups. The genus Lecanora is a perfect example for a poorly delimiting genus. Results of previous studies suggest that smaller genera are nested within the large genus. To better understand the delimitation of the genus and the relationships of species groups within Lecanora, I used a multi-locus approach and extracted DNA from new samples collected worldwide. These molecular data were used to infer a phylogenetic tree of the genus Lecanora. Techniques that were applied include DNA extraction, PCR amplification, gel electrophoresis, DNA sequencing, and alignment. Analysis of the molecular data was performed using maximum likelihood and Bayesian tree sampling. The trees showed that specimens sharing characters, such as secondary metabolites or general preferences for substrate, clustered together. Characters of the groups found will be discussed. This study demonstrates that by incorporating more loci in the phylogenetic analysis, the support for clades can be improved and our confidence in the phylogenetic estimate is enhanced. This study will provide a basis for a revised classification of the genus Lecanora.

Original Project Description: Lichen-forming fungi are a unique group of fungi that live in close associations with photosynthetic symbiotic partner (algae or cyanobacteria) that provide energy for the symbiotic system. The diversity of lichenized fungi is poorly known, especially in tropical habitats. In a project focusing on the tropical lichen family Graphidaceae, this project will address species delimitation in lichens in a phylogenetic context. DNA sequence data of different genes will be used to address the delimitation of specues. The lichens selected for this group belong to the genus Thelotrema within the family Graphidaceae (Ostropales).

Research methods and techniques: REU participants in this project will receive training in molecular and organismal research methods. They will learn how important a combination of both methods is for an understanding of the evolution of the diversity of life. The training will include introduction to the literature, handling of herbarium specimens. Chemical examination will include chromatographic methods, such as HPTLC and HPLC. Molecular methods will include DNA isolation, PCR and subsequent direct sequencing of certain gene regions. Subsequently, the analysis of DNA sequence data will be performed.