EARTH SCIENCE > Biosphere > Plant Taxonomy > Lichens
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Measurements of atmospheric ammonia, and chemical and physiological analyses of ecological materials collected at Cape Hallett, Antarctica
The dataset contains measurements of mean atmospheric ammonia concentrations taken at seven locations in and around Cape Hallett, northern Victoria Land. The data were obtained using ALPHA passive diffusion samplers mounted at a height of 1.5 m above ground. Samplers were exposed in triplicate at each site for three periods: 26th December 2005 to 10th January 2006, 11th to 17th and 17th to 23rd January 2006, which coincided with the penguin breeding season. Various chemical and physiological analyses of ecological materials were also conducted during the period December 2004 to January 2006, to study the effects of nitrogen enrichment on lichens. Analyses were performed on whole thalli of Umbilicaria decussata and Xanthomendosa borealis and the terminal 10-20 mm of Usnea sphacelata with Nitrogen (N), Phosphorus (P) and delta 15N values determined. Other samples analysed for N and P values include guano-rich surface soil collected from Seabee Hook to a depth of 5 mm, and an Adelie chick leg muscle, dissected from recent skua kills. Replicate values for phosphomonoesterase activity in the lichen species Usnea sphacelata, Umbilicaria decussata and Xanthomendosa borealis are listed. Lichen samples were collected from various Cape Hallett sites and analysed using the p-nitropenol phosphate method at a range of pH values.
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.
This database contains information on the herbarium specimens held in the herbarium of the British Antarctic Survey (international code AAS) as well as information about specimens collected in the Antarctic and sub-Antarctic and held in other world herbaria. There are over 70 000 records, predominantly of mosses and lichens, but also of vascular plants, ferns, fungi and algae collected in Antarctic and sub-Antarctic regions as well as some from surrounding continents, particularly South America. The collection from South Georgia And The South Sandwich Islands started in 1775 and from Antarctica in 1834. Documents relating to the Herbarium are kept in the BAS Archives (LS2/4). The records can be searched and downloaded on: http://apex.nerc-bas.ac.uk/f?p=148:1. There is also a facility to see a distribution map of specimens retrieved by querying the database.
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.