EARTH SCIENCE > Biosphere > Plant Taxonomy
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Genetic variation on a spatial scale was assessed, using both DNA fingerprinting and sequencing-based approaches, in the Antarctic endemics Buellia frigida, Carbonia vorticosa and Amandinea petermananii, and in the bipolar species Caloplaca saxicola, Umbilicaria decussata and Cladonia galindezii. PCR-based (Polymerase Chain Reaction) molecular biology techniques, were used as they are ideal for working with lichens because little starting material is required. See Fabian et al. 2007 for further information on analyses and results.
DNA fingerprints to determine self-fertilization (homothallism) or outcrossing (heterothallism) in Antarctic lichen
The majority of Antarctic lichens produce sexual organs, and in many species sexual ascospores appear to be the only reproductive propagule. However, it is unknown whether sexual reproduction involves selfing (homothallism) or outcrossing (heterothallism). To investigate this issue we have established axenic cultures of sexual progeny in order to generate DNA fingerprints and thereby determine the breeding system.
The fieldwork involved collection of fertile lichens from a range of sites across the Antarctic Peninsula and isolation of the lichen-forming fungi into pure culture in a laboratory at Rothera. Approximately 5,600 monospore cultures were isolated, including B frigida. Approximately 400 thalli of Usnea species, and 3 O. frigida thalli have also been collected for whole thallus analysis. Logarithmic sampling transects of B frigida were conducted at Rothera (2 transects) and on Anchorage Island (one transect) to examine the genetic variation and geographic variation. All thalli of B frigida collected from the transects were successfully used to generate viable spores from four individual apothecia from each thallus. 16 spores were subcultured and maintained from each apothecium.