Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The Cape Floristic Region (CFR) is situated at the southern tip of Africa and possesses a flora that
is unique amongst the floras of the rest of the world, both in terms of its incredibly high species
richness, and its high levels of endemism. Proteaceae, the family to which Serruria belongs, is
widely distributed amongst the landmasses of the southern hemisphere, with its centres of diversity
occurring in Australia and southern Africa.
Previous molecular and morphological analyses performed on the South African subfamily
Proteoideae have shown Serruria, a CFR endemic, to form a well-supported monophyletic group.
Based upon the strong monophyly of Serruria, DNA sequence data were collected for 53 of the 55
species from the plastid (rps16 intron, atpB-rbcL intergenic spacer, trnL-F region and psbA-trnH
intergenic spacer) and nuclear (internal transcribed spacer region or ITS) genomes in order to
investigate evolutionary relationships within the genus. Spatalla taxa were used as the outgroup.
Both parsimony and Bayesian analyses were carried out on each of these data sets. The resulting
trees were reasonably well resolved. All the Serruria taxa grouped together in a well-supported
clade, except for S. f1ava, which emerged well within the Serruria clade in the analyses of the
nuclear genome, but outside the clade in the plastid analyses. It was therefore proposed that this
taxon represents a hybrid. Apart from this case, there was widespread agreement between the
trees reconstructed using data from the two genomes. The plastid and nuclear data were therefore
combined in order to analyse the data sets together.
The molecular data does not support most of the groupings proposed by previous authors based
on morphological data. Additionally, in some cases, multiple representatives of species do not
group together. These specimens probably do not represent monophyletic taxa. Current ideas
about relationships within Serruria are based predominantly on floral characters, and it is
suggested that pollinator pressures have led to plasticity in the floral characters.
Consequently, it is evident from this study that relationships within Serruria need to be re-examined
in order to determine the patterns of evolution within the genus. / AFRIKAANSE OPSOMMING: Die Kaapse Floristiese Streek is aan die suiderpunt van Afrika geleë, en beskik oor 'n unieke flora
relatief tot ander wêreldfloras, beide ten opsigte van die ongelooflike hoë spesie diversiteit en die
hoë vlakke van endemisme. Proteaceae, die familie waaraan Serruria behoort, kom wydverspreid
tussen die vastelande van die Suidelike Halfrond voor, en het diversiteitsentrums in Australië en
suider Afrika.
Vorige molekulêre sowel as morfologiese analises wat op die Suid-Afrikaanse subfamilie
Proteoideae uitgevoer is, dui aan dat Serruria (wat endemies is tot die Kaapse Floristiese Streek)
'n goed ondersteunde monofiletiese groep is. Gebaseer op die sterk monofilie van Serruria, is
DNA-volgorde-data vir 53 van die 55 spesies vanuit die plastied (rps16 intron, atpB-rbcL
intergeniese spasie, trnL-F area en psbA-trnH intergeniese spasie) en kern (intern
getranskribeerde spasie area, ook ITS genoem) ingewin om die evolusionêre verwantskappe binne
die genus te ondersoek. Spatalla is as die buitegroep gebruik.
Beide parsimonie en Bayesian analises is op elk van hierdie datastelle uitgevoer. Die resulterende
bome het redelike hoë resolusie getroon. AI die Serruria-taxa het in 'n goed ondersteunde klade
saam gegroepeer, behalwe vir S. f1ava, wat binne die Serruria klade val vir die kern genoom, maar
buite die klade vir die plastied analise. Dit is dus voorgestel dat hierdie taxon as 'n hibried beskou
mag word. Behalwe vir hierdie geval, was daar wydverspreide ooreenstemming tussen die bome
wat verkry is vanaf data van die twee genome. Die plastied- en kern-data is derhalwe
gekombineer om die datastelle saam te kan analiseer.
Die molekulêre data ondersteun nie die meerderheid van morfologiese groeperings wat deur
verskeie outeurs voorgestel is nie. Verder, in sommige gevalle, groepeer verskillende monsters van
dieselfde spesies nie bymekaar nie. Dit is derhalwe voorgestel dat hierdia taxa nie monofileties is
nie. Huidige idees omtrent die verwantskappe binne Serruria is grotendeels op blommorfologiese
kenmerke gebaseer, en dit word voorgestel dat bestuiwing-druk gelei het tot plastisiteit van die
blommorfologiese kenmerke. Verskille tussen die bome wat uit plastied- en kern-data
gerekonstrueer is word aan vroeëre hibridisasie gebeure toegeskryf.
Op grond van hierdie studie is dit duidelik dat die verhoudings binne Serruria verder ondersoek
moet word om die patrone van evolusie binne die genus te bepaal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/50030 |
| Date | 04 1900 |
| Creators | De Villiers, Margaret J. (Margaret Jenifer) |
| Contributors | Reeves, G., Dreyer, L. L., Marais, E. M., 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 | 75 p. : ill. |
| Rights | Stellenbosch University |
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