Understanding morphological evolution in lichens

2012 REU Intern Bradley Loomis


Sophomore Biology major at Green Mountain College

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

Symposium Presentation Title: Species Delimitation and Evolution in the Foliose Lichen Genus Montanelia

Symposium Presentation Abstract: Species circumscriptions in lichenized fungi that focus primarily or entirely on morphology often have aggregated many genetically distinct species into single taxa. Results from recent molecular studies have shown the potential for morphologically cryptic species-level diversity within some groups that are considered virtually indistinguishable based on morphological characters. To better understand diversification within the foliose brown parmelioid lichens (family Parmeliaceae), sequence data from six genetic markers from 46 specimens representing the newly described genus Montanelia were analyzed within a phylogenetic context. The species of Montanelia occur on siliceous rocks in arctic-alpine habitats of the northern Hemisphere. The results from this research suggest that multiple traditionally circumscribed Montanelia species include previously unrecognized species-level diversity. Within the four traditionally circumscribed species investigated here, a total of nine candidate species were recognized. The results of this preliminary data show the limitations of using morphology to circumscribe species in Montanelia. Future studies investigating character evolution and the role of biogeography in the brown parmelioids will be essential to better understand biogeography and factors driving diversification in these commonly occurring lichens.

Original Project Description: Lichen-forming fungi are unique among the fungal kingdom since these organisms form specific vegetative thalli to host their photosynthetic symbiotic partner (wither algae or cyanobacteria) that provide energy for the symbiotic system. These thalli have certain morphologies and include adaptations, such as a cortex covering the algal layer to protect them from UV radiations. Other adaptations include crystals in the algal layer to increase the light intensity for species growing in shady habitats in tropical rainforests. Currently, our knowledge about the evolution of these adaptations is very poor. In a project focusing on the tropical lichen family Graphidaceae, this project will address the origin of morphological adaptations in a phylogenetic context. DNA sequence data will be used to address these issues. The lichens selected for this group belong to the so-called Topeliopsis clade 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 and 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.