Resolving Species Delimitations in Lichens

2011 REU Intern Warren Chatwin


Sophomore Genetics and Biotechnology major at Brigham Young University

REU Mentor: Dr. Thorsten Lumbsch (Curator, Botany)

Symposium Presentation Title: Resolving Species Limitations Among the Lichen Genus Melanohalea

Symposium Presentation Abstract: Lichens are known for being difficult to identify morphologically, so with the decreasing costs of DNA sequencing lichen classifications are being revised. In 2004 the lichen genus Melanohalea was created from the genus Melanelia after a study of morphological and molecular characteristics. In this study we are using two ribosomal markers, one mitochondrial marker, and three protein coding markers to determine the molecular phylogeny of 13 of the 22 recognized species of Melanohalea. Our findings indicate that the classification of Melanohalea is overall mostly correct with each lineage forming monophyletic groups, but those groups often have different sister taxa from gene to gene therefore each gene tree is not congruent with the others. There are also cryptic lineages present among a few species. The trees were created using total data as well as a coalescence approach. Further studies will be needed to completely resolve the relationships among these groups.

Original Project Description: Up to 1.5M species of fungi are estimated to exist in nature. With approximately 100K described species, only a small fraction is currently known. A large group of fungi forms associations with algae and cyanobacteria, so-called lichens. The circumscription of species in lichen fungi has been based on morphological characters. There is a growing body of evidence from DNA studies that these concepts underestimate the number of existing species. However, understanding the species circumscription in lichens is pivotal for our understanding of biodiversity. Lichens are important indicators for climate change, air pollution, forest health and potential sources of antibiotics and biocontrol agents. DNA sequence data will be used to address the species delimitations. The objective of the research is to address the species circumscription in two groups of parmelioid lichens, focusing on North American species of the Melanelixia fuliginosa and Melanohalea elegantula groups.

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.