Browsing by Author "Hall, Stuart"

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    Genetic and morphological means of differentiating within and between populations of Widdringtonia whytei and Widdringtonia nodiflora on Mount Mulanje, Malawi
    (2010) Hall, Stuart; Hedderson, Terry A; February, Edmund C
    There has been confusion in the past as to the taxonomy of Widdringtonia on Mount Mulanje. At present it is accepted that there are two species present. The aim of this study was to assess the level of genetic variation present across six populations of Widdringtonia whytei and Widdringtonia nodijlora on the mountain, and determine whether there are two genetically separate species present. Analysis of genetic variation included PsbA (chloroplast DNA), ITS (nuclear DNA), microsatellite and ISSR gene region markers. Out of the markers that amplified successfully, it was found that there is little genetic variation present with no differentiation between or within taxonomic groups for the gene regions analyzed. Morphometric analysis of cones and leaves grouped W. whytei and W. nodijlora separately, with a midgroup more closely associated with definite W. whytei. This compared favourably with observations of individuals from the different groups in the field. It is suggested that based on the low level of genetic variation across the mountain, W. whytei and W. nodijlora have diverged very recently from a W. nodijlora ancestor.
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    Vegetation change and vegetation type stability in the Cape of Good Hope Nature Reserve 1966 - 2010
    (2010) Hall, Stuart; Midgley, Jeremy J; Slingsby, Jasper A
    Vegetation stability was investigated within the Cape of Good Hope Nature Reserve by incorporating three vegetation surveys spanning a 44 year time period. The goals of this study were to investigate changes in overall species diversity within the reserve, stability of community composition within and between sites, and which factors are influencing stability. A survey was conducted on 26 vegetation plots across the reserve. Data from this survey and two previous surveys was used to compare species diversity between time periods. Vegetation compositional similarity was also compared between sites. I tested for the effect of difference in vegetation age and soil type as predictors of vegetation groups. Results showed an overall decrease in species diversity. Analysis ofvegetation groups showed that vegetation types are mostly stable as current vegetation can be predicted by groups based on 1966 data. Vegetation is influenced significantly by fire history and soil types.