Molecular Systematics, Coevolution, and Natural Products in Lichen Associations

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Michele D. Piercey-Normore

Professor and Curator of cryptogams (WIN)
508 Buller Building
Department of Biological Sciences
E-mail: pierceyn@cc.umanitoba.ca
Telephone: (204) 474-9610

Academic background

Ph. D. 
Department of Biology, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada.

Post doctoral research
Duke University, Durham, North Carolina, USA
Smithsonian Institution, Washington, DC, USA


Research interests

Lichenized fungi (mycobionts) and algae (photobionts) form highly successful partnerships in nature where the fungal partner may associate with more than one algal species, but multiple fungal species may also share the same algal species. This sharing of species provides many opportunities for different types of research questions. My research program reflects my broad interests in the ecology and evolution of this partnership covering these topics:
(1) coevolution and phylogenetics of the algal and fungal partners,
(2) patterns of algal selection by the mycobiont and habitat influences,
(3) environmental effects on gene expression during the symbiotic interaction and production of secondary metabolites,
(4) ecology and evolution of fungal polyketides, and
(5) biodiversity of lichens and bryophytes.

The phylogenetic history of lichens reflects the evolution of the fungal partner only. While my research has focused on the genus Cladonia, a large and widespread genus, I have also examined evolutionary history from the perspective of the co-evolving symbionts in other genera. Coevolution of both algal and fungal partners can be examined by comparing phylogenies of both symbionts to determine a strict vertical transfer of symbionts together (coevolution) or horizontal transfer where the same algal species is found to associate with multiple fungal species (algal switching). Algal switching (selection of the algal partner) may depend on the habitat to which the algal partner is adapted, the genetic compatibility between the two symbionts, or the type of reproduction of the lichen where vegetative propagules disperse with both symbionts but ascospores disperse alone, coming into contact with an algal partner after dispersal to a new habitat.

Environmental conditions may affect expression of recognition and defense related genes in both symbionts influencing the level of compatibility in different habitats. The effect of different habitats can be tested in the lab by resynthesis experiments in different culture conditions. Habitat conditions may also affect gene expression of polyketide synthase genes of lichen fungi resulting in production of different amounts or kinds of natural products (polyketides), produced in certain habitats. Since the function of polyketides is thought to reflect the habitat conditions such as protection of the lichen from excessive UV light, moisture, or chelation of metal ions, these natural products may be regulated by the habitat conditions. Chemical ecology of lichen polyketides may show large-scale changes with environmental or climatic conditions, which can be further tested by culturing lichen symbionts under controlled laboratory conditions.

As a member of the Lichens and Bryophytes Subcommittee for COSEWIC I am also interested in the biology and distribution of rare lichens and bryophytes. Floristic studies of cryptogam communities place ecology and evolution into a broader context and offer information on microhabitat and photobiont availability. The cryptogam collection at the University of Manitoba predominantly contains lichens as well as some bryophytes from Manitoba and other parts of Canada. The collection represents surveys, population, and phylogenetic studies and it provides a source of polyketides for collaborative studies with J. Sorensen in the Department of Chemistry. Rare species of lichens may be the result of one or both symbionts being rare. Conservation genetics incorporates the variation between lichen symbionts to establish a genetic basis for the uncommon occurrence of certain lichens. The genetic basis will play a role in conservation management of the species.

 
Publications

 

Meet my students...

Student experiences

My research program offers experiences for a wide range of students who are seeking hands-on experience in the lab or a higher education in some aspect of my research program. Students who are in high school have worked in my lab as SABC Aventis Biotechnology students and have won awards for their projects. Students who are pursuing their undergraduate degrees and would like hands-on lab experience have completed projects courses and published some of their work in journals. Students have also been volunteers in my lab for short periods of time to gain experience and explore their interests in research. Honours students in biology, microbiology, and chemistry have also completed their research projects in my lab. Lastly, graduate students pursuing longer-term research projects and a higher education in some aspect of my research program have committed to completing a MSc or PhD in my lab. After graduation these students have continued with their career interests in other labs, they have found jobs as technicians in industry and other organizations, or they have pursued teaching careers. In my research program, I encourage an atmosphere where students help and interact with each other, and learn as a group in weekly lab meetings. These lab meetings allow us to discuss their individual progress in the lab and any lab problems that have developed. We also critically evaluate published articles and practice oral presentations for various conferences and seminars.

 

Teaching interests

I teach part of an introductory course (BIOL 2260) on the biology of fungi and lichens where I cover the evolution and ecology of the ascomycetes from a functional perspective. At the end of the course you will understand the diversity of ascomycetes and basidiomycetes; how to recognize major groups of fungi; understand fungal methods for obtaining nutrition (functional groups); and you will have a general understanding of the biology of lichen-forming fungi. Bryology and Lichenology have been combined into a single course called Lichens and Bryophytes (BIOL 3250). This course covers the biology, evolution, and ecology of lichens and bryophytes. At the end of the course you should understand the diversity and life history strategies of both groups, how to recognize major groups of lichens and bryophytes, how lichens and bryophytes interact with animals, and the role of lichens and bryophytes in ecosystems. Both courses include a lab component that integrates with the lecture component. Students may also take a topics course (BIOL 4890) where we develop a lab project that will be evaluated on the lab work, a presentation, a proposal, and a term paper. I have also taught graduate courses including various topics courses (BIOL 7600) such as Population Genetics, Lichen ecology, and Lichen Identification. A number of workshops on lichen identification have also been offered in the past.