Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Marion Island is situated approximately 2600 km southeast of Cape Town and is the larger of
the two islands that comprise the Prince Edward Island group. During past glaciation events,
Marion was partially covered by ice with fauna and flora confined to isolated refugia across
the island. As a result of these long-term isolation events, it is postulated that species
predating these glaciation events might show geographic partitioning of genetic variation.
Subsequently, the majority of Southern Oceanic islands have a history of sealing activities
with vessels frequenting various islands in their hunt for seals. These combined visits to
several islands could have facilitated the introduction of alien species, or the reintroduction of
species already present on islands. These incidents, combined with more recent scientific
voyages, have led to the establishment of several exotic species on Marion Island. Two
indigenous Collembola species (Cryptopygus antarcticus (Willem, 1901) and Tullbergia
bisetosa (Börner, 1903)) were chosen as model species to investigate the possible effects of
glaciation on the spatial distribution of genetic variation on indigenous species. Given the
negative impact that alien taxa have on indigenous species and ecosystems, the
phylogeographic population structure of the recently introduced Isotomurus cf. palustris
(Müller, 1876) was determined and compared to those described for the two indigenous
species. To address these questions, two mitochondrial DNA genes were targeted:
cytochrome oxidase subunit I (COI) and cytochrome oxidase subunit II (COII). These genes
were sequenced (GENBANK accession numbers DQ147289-DQ147558) and analysed using,
amongst others, AMOVA (Analysis of Molecular Variance), SAMOVA (Spatial Analysis of
Molecular Variance) and NCA (Nested Clade Analysis). As expected, the two indigenous
species showed distinct signs of population expansion, whilst the recently introduced species
exhibits little genetic variance across its range. The life histories of species have an influence
on their resultant genetic signature; therefore life history parameters were incorporated to
explain differences in the phylogeographic patterns observed for these three species. / AFRIKAANSE OPSOMMING: Marion Eiland is die groter van twee eilande wat die Prins Edward eilandgroep vorm,
ongeveer 2600 km suid-oos vanaf Kaapstad. Gedurende glasiasie episodes in die verlede, was
Marion gedeeltelik met ys bedek en fauna en flora was geisoleer in klein gedeeltes van die
eiland wat beskut was. As gevolg van hierdie langtermyn isolasie word daar voorgestel dat
spesies wat op die eiland was voor hierdie gebeurtenisse plaasgevind het, ‘n geografiese
verdeling van genetiese variasie sal toon. Sedertdien het die meerderheid van die eilande in
die Suidelike Oseaan ook ‘n geskiedenis van skepe wat op een of meer van die eilande
aangedoen het in die jag op robbe. Hierdie besoeke deur die robjagters aan die eilande het
meegebring dat daar eksotiese spesies op die eiland aangekom het of dat spesies wat reeds op
die eiland voorgekom het, opnuut daar geland het. Hierdie, tesame met die onlangse
wetenskaplike reise na Marion Eiland, het daartoe gelei dat baie eksotiese spesies ingevoer is
na die eiland. Twee inheemse spesies, naamlik Cryptopygus antarcticus (Willem, 1901) en
Tullbergia bisetosa (Börner, 1903) is gekies om as model spesies te dien om die moontlike
gevolge van glasiasie op die geografiese verspreiding van genetiese variasie te toets. In ag
geneem die moontlike negatiewe impak wat eksotiese spesies op die inheemse spesies mag
hê, is die filogeografie van ‘n uitheemse spesie, Isotomurus cf. palustris (Müller, 1876) ook
bepaal en vergelyk met díe van die bogenoemde inheemse spesies. Dit is gedoen deur twee
gene, sitokroom oksidase I (COI) en sitokroom oksidase II (COII) te analiseer. Hierdie gene
se basispaarvolgordes is bepaal (GENBANK toetreenommers DQ147289-DQ147558), en
hulle is ge-analiseer deur gebruik te maak van AMOVA (Analise van Molekulêre Variasie),
SAMOVA (Ruimtelike Analises van Molekulêre Variasie) en NCA
(geseteldegroepsanalises). Net soos verwag, het die twee inheemse spesies albei duidelike
tekens getoon van ‘n bevolkingstoename terwyl die uitheemse spesie amper geen variasie oor
sy verspreidingsgebied getoon het nie. Die lewensstyle van spesies het ‘n beduidende invloed
op hulle genetiese bevolkingstruktuur. As sulks is díe in ag geneem om die verskille tussen
hulle genetiese strukture te verduidelik.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21686 |
| Date | 04 1900 |
| Creators | Myburgh, Marike |
| Contributors | Jansen van Vuuren, Bettine, Daniels, Savel R., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xi, 68 leaves : ill. |
| Rights | Stellenbosch University |
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