Genetic variation within and between some rare and common taxa of Cape Proteaceae and the implications for their conservation

Brown, Susan Ann (2000) Genetic variation within and between some rare and common taxa of Cape Proteaceae and the implications for their conservation. PhD thesis, Rhodes University.




There are 152 rare, threatened or extinct Cape Proteaceae, many of which are found to occur in small numbers, have few populations, or a geographical range of less than 5 km2. This suggests that small nature reserves would be an ideal solution to protect such species provided they contain sufficient levels of genetic variation for long term viability. Genetic variation was measured using RAPD analysis in the rare Leucadendron elimense with its three closely related subspecies, L.e. vyeboomense, L.e. salteri and L.e. elimense. L.e. vyeboomense is restricted to a single endangered population, L.e. salteri has seven known populations and is ascribed the status of vulnerable, and the local endemic of the south coast plains, L.e. elimense, is considered vulnerable. AMOVA analysis of the RAPD results revealed high levels of genetic variation within populations of all three subspecies at 69.8 to 91.4%. The endangered L.e. vyeboomense was genetically most distant from the other two subspecies at a level of 0.40 and 0.39 and also showed the lowest levels of variation within the subspecies at 0.24. Populations of the other two subspecies had levels of variability of about 0.35. Comparable levels were recorded for the ubiquitous Leucadendron salignum. Serruria roxburghii, an endangered species restricted to two populations on a specialised sandy soil, provided another test of the applicability of the method. Both populations of S. roxburghii showed a genetic variability of 0.36 with no significant differences in genetic distances within the two populations. Morphological differences were considered and leaf ratios provided a tool for distinguishing the three subspecies. Total protein electrophoresis and sequencing of the Internal Transcribed Spacer (ITS) region, both showed that L.e. salteri was the least similar of the subspecies, and should be considered for possible taxonomic revision to species level. The implications of the thesis for conservation are that RAPD data is directly of use in conservation management decisions. It has shown that despite the small population sizes of the study taxa they have adequate to high levels of genetic diversity and would be adequately protected in small nature reserves. Small, private reserves should be considered as a potential economical and ecological long term viable option.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Proteaceae, South Africa, Plant conservation
Subjects:Q Science > QK Botany
Divisions:Faculty > Faculty of Science > Biochemistry, Microbiology & Biotechnology
Faculty > Faculty of Science > Botany
ID Code:2337
Deposited By: Mrs Carol Perold
Deposited On:11 Jan 2012 13:28
Last Modified:11 Jan 2012 13:28
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