Student Number : 9903228W -
MSc dissertation -
School of Molecular and Cell Biology -
Faculty of Science / Plant populations show an ability to survive and adapt under varying environmental
conditions. Adaptation to heavy metal contaminated soils usually results in a decrease
in genetic variation. Slimes dams consist of the pulverized rock slurry left after the
extraction of gold or uranium. High toxicity levels mean that these wastes often remain
uncolonised and are therefore easily eroded through wind or water. Plant populations
that will be viable for long-term vegetation of slimes dams will prevent erosion, and
stabilise and improve the quality of the soil. Indigenous, locally adapted species are the
most likely to be successful candidates for vegetation. Indigenous, slimes-tolerant
species Indigofera adenoides and Indigofera zeyheri were therefore studied. The aim
was to determine if plant populations show local adaptation to the adverse substrate
conditions emanating from slimes dams, by investigating genetic and morphological
variation between adjacent populations growing at different distances in relation to
slimes dams. The AFLP technique was used to analyse genetic variation as it produces
rapid results, is inexpensive, reproducible, and capable of screening the entire genome.
Lower genetic diversity was observed in those areas of the dams with higher levels of
slimes-associated contamination. This difference was observed in both species, and for
all measures of genetic diversity (Shannon’s information index, Nei’s gene diversity,
percentage of loci polymorphic). This may be due to a founder effect following
colonisation, natural selection, flowering time differences, or a combination of these
factors. Reduced morphological variation was observed in those areas of the dams with
higher levels of slimes-associated contamination. Significant morphological differences
were observed between groups of plants from different areas, some of which appear to
have the capability to assist the plants in a slimes-contaminated environment. Some
degree of adaptation to slimes-contaminated soil therefore seems to have occurred, with
this being more pronounced in Indigofera adenoides, although it cannot be determined
whether this is purely phenotypic, or a combination of phenotypic and genetic. These
species therefore seem suitable as candidates for vegetation of slimes dams, although
further work must be done to fully understand the effect of slimes-associated toxicity.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1730 |
| Date | 15 November 2006 |
| Creators | Angus, Caroline Jane |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 44727 bytes, 6887623 bytes, application/pdf, application/pdf, application/pdf, application/pdf |
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