- Title
- Phylogeny and phylogeography of dominant South African surf diatoms
- Creator
- Du Preez, Debbie Patricia
- Subject
- Phylogeography -- South Africa
- Subject
- Diatoms -- South Africa Phylogeny -- Molecular aspects DNA -- Analysis
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10948/29794
- Identifier
- vital:30778
- Description
- Genetic studies of diatoms are lagging behind those on other organisms. The reasons for this are, among others, that many species are difficult to culture (some surf diatoms in particular), single cells contain only a small amount of DNA, and selection of single cells from environmental samples is difficult. Globally, there are only a few species of surf diatom: Anaulus australis Drebes et Schultz, Asterionellopsis glacialis (Castracane) Round, Asterionellopsis socialis (Lewin & Norris) Crawford & Gardner, Attheya armata (West) Crawford, Aulacodiscus petersii Ehrenberg, Aulacodiscus johnsonii Arnott, Aulacodiscus kittonii Arnott ex Ralfs and Aulacodiscus africanus Cottam. These species occur exclusively in the surf zone with the exception of A. glacialis, which is also found in coastal and oceanic waters. The overall aim of this project was to investigate the phylogeny or the phylogeography of the two dominant South African surf diatoms. In order to do this, it was necessary to develop methods for extracting DNA from environmental surf diatom patch samples. This method was then used in the investigation into the phylogeography of Anaulus australis along the South African coastal zone. Due to other recent work into diatom phylogeny and phylogeography there was also the opportunity to compare the genetics of the South African surf diatom Asterionellopsis found at Sundays River Beach to localities recently sampled and sequenced around the globe in order to identify the species found in South Africa. The direct method was successful for DNA extraction from Anaulus australis cells preserved using either isopropanol, ethanol or glutaraldehyde (provided the samples were not older than two years), but not formalin. Extraction of DNA from Asterionellopsis glacialis s.l. cells was successful with the direct method for ethanol-preserved samples, but the extraction from Attheya armata cells required some modifications be added to the method. Sequencing of the ITS region of Anaulus australis cells from along the southern coast of South Africa indicated connectivity between the various populations rather than the expected isolation of populations in the surf zones of the log-spiral bays. Comparison of the ITS and RbcL regions of the species of Asterionellopsis found at the Sundays River Beach indicated that it is Asterionellopsis lenisilicea which is a species only ii recorded from Canada to date and which has only recently been discovered and recognised as a new species within the genus. This genetic identification was supported by morphological measurements of frustules.
- Format
- viii, 61 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
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