Genetic variation in the lichens Buellia frigida and Xanthoria elegans from the Vestfold Hills, eastern AntarcticaEntry ID: PSD1-Nottingham
Abstract: Antarctica is a desert continent dominated by micro-organisms. The seals and penguins, which are conspicuous around its margins, depend upon the sea for their food resources and are effectively part of the marine food chain. Life depends upon the availability of free water. In Antarctica water is usually locked up in ice, only in summer is there free water in the terrestrial environment. Not only ... is water limited, but low temperatures and low levels of nutrients severely limit the scope for growth among the micro-organisms that have managed to colonise the continent. Propagules are brought to the continent in a number of ways. Some arrive in the air masses that flow around the Earth. Once deposited some simply cannot survive the extreme conditions, while others may become established. Other species of micro-organism may be introduced by Man around the scientific stations on the continent. During the ice-ages which have occurred repeatedly through geological history, micro-organisms may have survived in refugia offered by nunataks or in the ice, and have recolonised more widely following ice retreat.
This project will concentrate on one group of micro-organisms, the fungi. We will use special air samplers to determine which species are brought to the continent in the winds and we will compare the propagules from these samplers with the species living in the 'soil' and samples grown up from ice samples, where the resting spores can remain dormant of hundreds of years. We will analyse the communities of fungi that are found in the proximity of scientific stations and compare them with 'natural' communities in Antarctica, to determine what impact Man has had on introducing fungal species. The data generated will provide us with an insight into the colonisation of Antarctica by fungi. As global warming continues, species hitherto unable to establish may be able to do so. It is important to have a baseline on what is currently living on the continent, so that we can monitor the establishment of new species in the future.
Thalli of the lichens Buellia frigida and Xanthoria elegans were collected from five different locations each 5-15 km apart in the Vestfold Hills, Princess Elizabeth Land, eastern Antarctica. A further collection was made from Mawson Station, Mac Robertson Land, eastern Antarctica 660 km away. DNA was extracted from whole thalli and the ribosomal ITS region amplified by PCR using fungal specific primers. Resulting products were sequenced to gain an indication of whether or not variation was present within populations of lichen-forming fungi from continental Antarctica, and therefore of the availability of genetic resources to react to pressures such as climate change. Three genotypes of B. frigida and two of X. elegans were detected in the Vestfold Hill collections. However, these differed by only one nucleotide position suggesting the presence of relatively little genetic variation if the ITS region is indicative of the overall genome. B. frigida collected from Mawson Station had an identical ITS region sequence to the most common Vestfold Hills genotype, indicating that this species may have a low level of genetic variation across much of eastern Antarctica. In contrast, X. elegans collected from Mawson showed considerable genetic variation from the Vestfolds thalli, differing at 14.2 % of nucleotide positions and had an identical ITS region sequence to an isolate from maritime Antarctica 4960 km away. Samples from the Vestfold Hills formed a distinct cluster in a phylogenetic analysis of ITS sequences from a worldwide collection of X. elegans isolates.
The collection sites used in this study were:
Lichen Valley, Vestfold Hills
Stalker Hill, Vestfold Hills
Ellis Rapids, Vestfold Hills
Trajer Ridge, Vestfold Hills
Boulder Hill, Vestfold Hills
The DNA sequences arising from the lichens can be accessed from Genbanks Entrez Nucleotide Sequence Search, the accession numbers are:
This work was carried out as part of ASAC project 1201 (ASAC_1201).
Start Date: 1999-11-01Stop Date: 1999-12-16
ISO Topic Category
Quality DNA sequences were all double strand sequenced to ensure reliability of data. All Buellia frigida isolates gave similar results. Samples of Xanthoria elegans were more variable, suggesting an underlying taxomonic problem.
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Phone: +44 (0117) 3314120
Email: Jo.Laybourn-Parry at bristol.ac.uk
University of Bristol School of Geographical Sciences University Road
Province or State: Bristol
Postal Code: BS8 1SS
Country: UNITED KINGDOM
Role: TECHNICAL CONTACT
Role: DIF AUTHOR
Email: Paul.Dyer at Nottingham.ac.uk
Department of LIfe and Environmental Sciences University Park University of Nottingham
Postal Code: NG7 2RD
Dyer PS, Murtagh GJ (2001). Variation in the ribosomal ITS-sequence of the lichens Buellia frigida and Xanthoria elegans from the Vestfold Hills, eastern Antarctica. Lichenologist 33: 151-159.
Dyer PS, Murtagh GJ, Crittenden PD (2001). Use of DNA fingerprinting and vegetative incompatibility tests to investigate thallus individuality and genetic variation within lichen-forming fungi. Symbiosis (in press).
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DIF Creation Date: 2001-07-05
Last DIF Revision Date: 2014-01-10