Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: An understanding of the phylogeography and evolutionary processes involved in speciation is essential for the conservation and management of any particular species. To investigate the phylogeographic patterns in Agama atra from the Cape Fold Mountains (CFM), 98 individuals from 38 geographically close localities were analysed. In addition, to understand the phylogeographic associations between the CFM populations and the rest of Southern Africa, 18 specimens from 12 localities outside the CFM were also included. A total of 988 characters derived from two mitochondrial DNA fragments (control region and ND2) revealed 59 distinct haplotypes in the CFM. Parsimony, Bayesian and maximum likelihood analyses revealed four distinct clades associated with geography within the CFM. These clades were supported by a haplotype network and were defined as the Cape Peninsula clade, the Limietberg clade, the northern CFM clade and the central CFM clade. Analysis of molecular variance confirmed the high degree of genetic structure within the CFM, with more than 75% of genetic variation found among the geographic areas. SAMOVA and nested clade analysis (NCA) suggest that the central CFM clade may be more diverse than detected by the networks and the phylogenetic analyses. The processes that caused the four distinct genetic groups in the CFM are not yet clear. Using a speculative molecular clock estimate, the main cladogenesis of A. atra within the CFM took place, approximately ~6.5 - 9 MYA. This dating coincides well with the documented Miocene-Pliocene climate fluctuations which might have contributed towards the isolation among lineages. The genetic structure found in A. atra is also markedly congruent with what has been found in other taxa such as Mesamphisopus spesies, Potamonautes brincki, and Pedioplanis burchelli and this would further support vicariance as a main isolating factor here. / AFRIKAANSE OPSOMMING: ‘n Goeie begrip van die filogeografie en die evolusionêre gebeurtenisse wat verband hou met spesiasie is belangrik vir die bewaring en bestuur van enige spesie. Om die filogeografiese patrone in Agama atra van die Kaapse Plooiberge (KPB) te ontleed, was 98 individue van 38 nabygeleë lokaliteite geanaliseer. Tesame met bogenoemde monsters was 18 individue van 12 lokaliteite van buite die KPB ook geanaliseer om die filogeografiese verwantskappe tussen die KPB bevolkings en die res van Suidelike Afrika te ondersoek. Uit ‘n totaal van 988 karakters verkry uit twee mitochondriale DNS fragmente (die kontrole gebied en ND2) is 59 haplotipes gevind. Parsimonie en modelgebaseerde filogenetiese analises dui daarop dat vier groepe geassosieer met geografie binne die KPB voorkom. Die groepe word geondersteun deur ‘n haplotipe netwerk en word soos volg gedefinieer: ‘n Kaapse Peninsula groep, ‘n Limietberg groep, ‘n noordelike KPB groep en ‘n sentrale KPB groep. Analises van molekulêre variansie (AMOVA) bevestig die hoë graad van genetiese struktuur binne die KPB, met meer as 75% genetiese variasie gevind tussen die geografiese areas. SAMOVA en gesetelde groep analises (“NCA”) stel voor dat die sentrale KPB groep dalk meer variasie vertoon as wat die netwerk en filogenetiese analises vertoon. Die prosesse wat die vier genetiese groepe tot stand gebring het is nog nie bekend nie. Volgens ‘n spekulatiewe molekulêre klok berekening het die hoof kladogenese van A. atra binne die KPB ongeveer ~6.5 - 9 miljoen jaar (MJ) gelede plaasgevind. Hierdie datering stem goed ooreen met die gedokumenteerde Mioseen-Plioseen klimaat veranderinge wat isolasie van die groepe kon bewerkstellig het. Die genetiese struktuur van A. atra in the KPB is ook gevind in ander taksa soos Mesamphisopus spesies, Potamonautes brincki, en Pedioplanis burchelli en bevestig dus dat vikariansie hier die hoof faktor vir isolasie is.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2007. / The ability of various molluscan species to accumulate toxicants such as cadmium from natural waters in quantities that are many orders of magnitude higher than background levels are well-known. This phenomenon of bioaccumulation might cause certain stress responses in these organisms at the cellular level, which can be measured using biomarkers. A biomarker response test known as the neutral red retention assay was employed in this study to measure responses in four intertidal species. Specimens of Cymbula oculus (Born), Scutellastra longicosta (Lamarck), Cymbula granatina (Linnaeus) and Scutellastra granularis (Linnaeus) were collected at two localities on the coast of False Bay, South Africa. Laboratory exposures in static flow tanks at three different concentrations i.e. 0.8, 1 and 1.2 mg/L of CdCl2 were done respectively for each species over a three day exposure period i.e. each exposure concentration had an exposure period of 24, 48 and 72 hours. After every 24 hour exposure period the lysosomal membrane integrity was determined using the neutral red retention method to establish which species is the most sensitive to Cd. Both control and exposure groups for all species showed a decrease in retention times with an increase in Cd concentration over the exposure period. This decrease was particularly prominent at the highest exposure concentration after 72 hours. At 0.8 and 1.2 mg/L CdCl2 exposures an indirectly proportional relationship between neutral red retention time and heavy metal concentration was prominent in C. oculus, indicating a dose related response. In all species there was a moderate increase in heavy metal concentration over the 72 hour exposure period. EC50 values indicated that S. granularis and C. granatina had a “high” sensitivity to Cd contamination, while C. oculus had “medium” sensitivity and S. longicosta “low” sensitivity to Cd contamination. The sensitivity data obtained from the analysis of the experimental species in this study may contribute to the eventual establishment of a species sensitivity distribution model (SSD).

Thesis (PhD) -- Stellenbosch University, 1995. / ENGLISH ABSTRACT: Graling in the Kruger National Park. south of Phalaborwa Gate, is contaminated with copper, probably from a nearby copper refinery. Cattle in the neighbourhood have died from copper poisoning while the average copper concentration in the livers of impala in the Krgler National Park, was found to be abnormally high. The possibility exists that the ultrastructure of spermatozoa may serve as an indicator of environmental conditions. To examine this statement further, the purpose of this study includes the following: - To describe the ultrastructure of normal impala sperm as well as their abnormalities. - To quantify the sperm abnormalities of each experimental animal and to relate the abnormalities with the copper concentration in the impala liver, in order to determine whether any correlation exists between these two variables. Impala have been terminated monthly, from 1992.06.09 to 1993.05.15. in the vicinity of Phalaborwa Gate and in the Skukuza area for other research projects. Their sperm were made available for this study. The control group consisted of 20 animals which comprised 14 animals from an area, not contaminated with copper, along the Nwaswitshaka spruit near Skukula and 6 animals originally from the same area but which had been kept in captivity at Skukuza on a diet, not contaminated with copper. The experimental group consisted of 44 animals which comprised 32 animals from copper contaminated grazing along the Tshutshi spruit south of Phalaborwa Gate and 12 animals captured along the Nwaswitshaka spruit which were kept on a copper contaminated diet in captivity at Skukuza. Sperm from the epididymis of each animal were collected and fixed in a temporary laboratory. The sperm were processed at the Electron Microscopy Unit of the Faculty of Veterinary Science of the University of Pretoria and studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The copper concentration in the liver was analyzed and bone marrow collected of each animal in order to determine the condition of the animal. The external morphology of a normal impala sperm was documented by means of SEM and the dimensions of the sperm determined. SEM micrographs of observed sperm abnormalities were taken. Percentages for normal sperm and the percentages of some abnormalities of a control group (Average liver copper concentration - ALCC = 37.9 ppm WB) were calculated. The same percentages were also calculated for an experimental group (ALCC = 104 ppm WB). The control group and the experimental group exhibited 91.6% and 93.6% normal sperm respectively. The difference in percentage sperm abnormalities of the two groups was of the same order. The increased copper in the livers of the experimental group has thus not lead to an increase of the percentage macro-abnormalities observed with SEM. The ultrastructure of normal impala sperm were described and documented with micrographs by means of TEM. The deviations of the normal sperm ultrastructure were also recorded on micrographs. Percentages were calculated for the normal sperm sections, as well as the abnormalities of some sperm sections of a contrl group (ALCC = 33.86 ppm WB). The same percentages were also calculated for an experimental group (ALCC = 122.5 ppm WB). For the control group the average percentage sperm neck sections with vacuoles was : 31.5% and for the experimental group this percentage was : 57.9%. The increased copper concentrations in the livers of the experimental group thus led to an increase of the percentage of sperm necks with vacuoles. There is also reason to believe that the difference of the percentages of sections of the sperm head, in the control and experimental group, should be remarkably greater. A graphic analysis of the TEM-data has also shown that a statistically significant correlation exists between the percentage of sperm with vacuoles in the neck and the copper concentrations in the livers of impalas. The conclusion is that high level copper concentrations exert a detrimental effect on the ultrastructure of the sperm neck. The possibility also exists that copper concentrations in impala liver > 500 ppm WB. will show a correlation with the percentages of some of the other abnormalities observed. / AFRIKAANSE OPSOMMING: Die weiding suid van Phalaborwahek in die Krugerwildtuin word waarskynlik vanaf 'n nabygeleë kopersmeltery met koper besoedel. Van die plaasdiere in die omgewing het reeds van kopervergiftiging gevrek en die gemiddeIde koperkonsentrasie in die lewers van rooibokke is abnormaal hoog. Die moontlikheid bestaan dat die ultrastruktuur van spermatozoa as 'n indikator van omgewingstoestande kan dien. Om bogenoemde moontlikheid verder te ondersoek was die doelwit van hierdie studie die volgende: Om die ultrastruktuur van normaIe rooiboksperme en hulle abnormaliteite te beskryf en die spermabnormaliteite van elke proefdier te kwantifiseer en met die koperkonsentrasie in die lewer in verband te bring om sodoende te bepaal of daar 'n korrelasie tussen die twee veranderlikes bestaan. Rooibokke wat maandeliks vanaf 1992.06.09 tot 1993.05.15 vir ander navorsingsprojekte in die omgewing van Phalaborwahek en Skukuza getermineer is, se sperme is vir die studie beskikbaar gestel. Die kontrolegroep het bestaan uit 20 diere wat saamgestel is uit 14 diere afkomstig van die Nwaswitshakaspruit naby Skukuza, uit 'n gebied wat nie met koper besoedel is nie en 6 diere uit 'n groep wat oorspronklik uit dieselfde gebied gekom het, maar wat te Skukuza in aanhouding geleef het op voedsel wat nie met koper besoedel was nie. Die eksperimentele groep het bestaan uit 44 diere waarvan 32 in die omgewing van die Tshutshispruit suid van Phalaborwahek versamel is en die ander 12 diere is langs die Nwaswitshakaspruit gevang en op 'n koperbesoedelde dieet te Skukuza aangehou. Sperme uit die epididymis van elke dier is in 'n tydelike laboratorium versamel en gefikseer. By die Elektronmikroskopie Eenheid van die Fakutreit van Veeartsenykunde van die Universiteit van Pretoria is die sperme voorberei en met behulp van skandeerelektronmikroskopie (SEM) en transmissie-elektronmikroskopie (TEM) bestudeer. Die koperkonsentrasie in die lewer is bepaal en murgvet is versamel om die kondisie van die diere te bepaaI. Met SEM is die uitwendige morfologie van 'n normale rooiboksperm met mikrograwe gedokumenteer en die mates van die sperm bepaal. Mikrograwe van waargeneemde spermabnormaliteite is met SEM geneem. Persentasies is vir normale sperme en die abnormaliteite van sommige sperme van 'n kontrolegroep (Gemiddelde lewerkoperkonsentrasie - GLKK =37.9 dpm NB) bereken. Dieselfde persentasies is ook vir 'n eksperimentele groep (GLKK = 104 dpm NB) bereken. Van die kontrolegroep het 91.6% en van die eksperimentele groep 93.6% sperme normaal vertoon. Die verskil in persentasies spermafwykings van die twee groepe was ook van dieselfde orde. Die verhoogde koperkonsentrasie in die lewers van die eksperimentele groep het dus nie gelei tot 'n verhoging van die persentasie makro-abnormaliteite wat met SEM waargeneem is nie. Die ultrastruktuur van 'n normale rooiboksperm is met behulp van TEM beskryf en met mikrograwe gedokumenteer. Die afwykings van die spermultrastruktuur is ook op mikrograwe vasgelê. Persentasies is vir die normale spermsneë en die abnormaliteite van sommige spermsneë van 'n kontrolegroep (GLKK = 33.86 dpm NB) bereken. Dieselfde persentasies is ook vir 'n eksperimentele groep (GLKK = 122.5 dpm NB) bereken. Vir die kontrolegroep was die persentasie neksneë met vakuoles = 31.5% en vir die eksperimentele groep was die persentasie = 57.9%. Die verhoogde koperkonsentrasie in die lewer van die eksperimentele groep het dus gelei tot 'n verhoging van die persentasie neksneë met vakuoles. Rede bestaan om te glo dat die verskil van die persentasies kopsneë van die kontrole- en eksperimentele groep ook aansienlik hoër behoort te wees. 'n Grafiese analise van die TEM-data het ook getoon dat daar 'n statisties betekenisvolle korrelasie tussen die persentasie spermnekke met vakuoles en die koperkonsentrasie in die lewer van rooibokke bestaan. Die bevinding is dat hoë lewerkoperkonsentrasies 'n nadelige invloed op die ultrastruktuur van die spermnek uitoefen. Die moontlikheid bestaan ook dat koperkonsentrasies in die lewer > 500 dpm NB ook 'n korrelasie met sommige van die ander abnormaliteite sal toon.

Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Increases in taxonomic sampling and the numbers and types of markers used in phylogenetic studies have resulted in a marked improvement in the interpretation of systematic relationships within Eutheria. However, relationships within several clades, including Paenungulata (Hyracoidea, Sirenia, Proboscidea), remain unresolved. Here the combination of i) a rapid radiation and ii) a deep divergence have resulted in limited phylogenetic signal available for analysis. Specifically i) a short internode separating successive branching events reduces the time available for changes to occur, while ii) the longer the time since divergence, the greater the opportunity for signal to be negatively affected by homoplasy. This is evident in both molecular and morphological data where an overall consensus on paenungulate relationships is lacking. Morphological analysis of anatomical and fossil evidence favours the association of Sirenia (S) and Proboscidea (P) (Tethytheria) to the exclusion of Hyracoidea (H); further, support for uniting these three taxa as Paenungulata is contentious. In contrast, molecular data provide strong support for Paenungulata but intra-ordinal relationships are ambiguous. Although results from mitochondrial DNA sequence data favour Tethytheria, there is no consensus of support for this clade from nuclear DNA. Nuclear DNA is typified by node instability but favours H+P in the largest concatenation of sequences. Due to the expected increased effect from homoplasy and consequently the increased likelihood for misleading signal, it is unclear which result is most likely to represent the “true” tree. An analysis of available and added intron sequences to characterise signal heterogeneity among nuclear DNA and mitochondrial DNA partitions indicated that the phylogenetic utility of partitions varies considerably. Subpartitioning of the data according to similar evolutionary processes/characteristics (e. g., mtDNA vs. nDNA and codon position) revealed new insights into the signal structure of the data set; specifically i) that nuclear DNA first codon positions, and to a lesser degree second codon sites, provide convincing support for H+P, and ii) that support for S+P by faster evolving sites within mtDNA suggests that this may be the result of misleading signal. If H+P represents the “true tree”, then support for this clade indicates that phylogenetic signal has been reduced over time as a result of multiple hits, which explains the presence of (hidden) support in slower evolving sites where homoplasy is less likely to occur, in contrast to faster evolving sites where no support for H+P was observed. In an attempt to provide further resolution from an alternative perspective to that possible with DNA sequence data, chromosomal rearrangements were identified among the three paenungulate lineages. Using comparative chromosome painting, unique changes within each order and specific to Paenungulata were characterised, however, intra-ordinal synapomorphies were not recovered. Although this may suggest a hard polytomy, the slow to moderate rate of evolution estimated from the data is likely not sufficient relative to the rapid radiation associated with the paenungulate node. Further examination of chromosomal rearrangements at a higher level of resolution may yet reveal informative changes. / AFRIKAANSE OPSOMMING: ‘n Toename in die aantal taksonomiese monsters sowel as die aantal en soort merkers wat in filogenetiese studies gebruik word, het tot ‘n merkbare verbetering in die vertolking van sistematiese verwantskappe binne die Eutheria gelei. Desondanks bly ‘n aantal klades (stamlyne), met inbegrip van Paenungulata (Hyracoidea, Sirenia, Proboscidea), steeds onopgelos. By laasgenoemde het die kombinasie van i) ‘n vinnige radiasie en ii) ‘n diep divergensie die filogenetiese sein wat vir analise beskikbaar is, beperk. Meer spesifiek sal i) opeenvolgende vertakkings wat deur kort internodusse geskei word die beskikbare tyd waartydens veranderings kan intree, verminder, terwyl ii) ‘n toename in tydsverloop sedert divergensie die kans dat die sein deur homoplasie nadelig beïnvloed sal word, vergroot. Dit word in sowel molekulêre en morfologiese data, waar ‘n oorhoofse konsensus t.o.v. verwantskappe van Paenungulata ontbreek, waargeneem. Morfologiese analise van anatomiese en fossielbewyse ondersteun die samevoeging van Sirenia (S) en Proboscidea (P) (Tethytheria) ten koste van Hyracoidea (H). Ondersteuning vir die samevoeging van dié drie taksa as Paenungulata is egter aanvegbaar. In teenstelling hiermee word Paenungulata sterk deur molekulêre data ondersteun, al bly die verwantstkappe op intra-orde vlak, steeds onduidelik. Alhoewel die resultate van mitochondriale DNA op Tethytheria dui, word die klade nie deur data van kern-DNA ondersteun nie. Kern-DNA word gekarakteriseer deur node instabiliteit maar verkies H+P in die grootste samevoeging van geen volgordes. Na aanleiding van die verwagte toename in die effek van homoplasie en die gevolglik groter kans op ‘n misleidende sein, is dit nie duidelik watter van die resultate die meer korrekte filogenetiese stamboom verteenwoordig nie. Analise van beskikbare en nuut toegevoegde intron-volgordes om sein-heterogeniteit tussen kern- en mitochondriale DNA verdelings te karakteriseer, toon dat die filogenetiese nut van verdelings beduidend verskil. Onderverdeling van die data op grond van soortgelyke evolusionêre prosesse/karaktereienskappe (bv. mtDNA vs. nDNA, en kodonposisie) het na nuwe insigte in die seinstruktuur van die datastel gelei. Meer spesifiek dat i) kern-DNA se eerste kodonposisies, en tot ‘n mindere mate die tweede kodonposisies, H+P oortuigend ondersteun en ii) dat ondersteuning vir S+P deur posisies binne mtDNA wat vinnig verander, op ‘n misleidende sein mag dui. As H+P die korrekte stamboom verteenwoordig dui ondersteuning vir die klade op ‘n filogenetiese sein wat met verloop van tyd as gevolg van veelvuldige seinvoorkomste verklein het. Dit verklaar die aanwesigheid van versluierde ondersteuning in stadig-veranderende posisies waar die neiging tot homoplasie klein is, in teenstelling met posisies wat vinniger verander en waar ondersteuning vir H+P nie waargeneem is nie. Op soek na verhoogde resolusie vanuit ‘n ander perspektief as DNA-volgordebepaling, is chromosomale herrangskikkings in die drie stamlyne van Paenungulata nagevors. Met behulp van vergelykende chromosoomkleuring is unieke veranderings binne elke orde en spesifiek binne Paenungulata gekarakteriseer, maar geen sinapomorfe kenmerke is op die intra-orde vlak gevind nie. Alhoewel dit op ‘n onopgeloste politomie mag dui, is die stadige tot matige evolusietempo wat van die data afgelei word, relatief tot die vinnige radiasie wat met die Paenungulata-nodus geassosieer word, waarskynlik onvoldoende vir ‘n oplossing. Verdere navorsing oor chromosomale herrangskikkings met ‘n hoër resolusievlak mag addisionele insiggewende veranderings aantoon.

Balancing increasing elephant numbers with biodiversity conservation in small reserves has become a concern for many protected area managers. Elephants are considered important agents of disturbance creating heterogeneity and thus contributing to the maintenance of biodiversity. However elephants also damage vegetation through their destructive feeding habits, and this has led to pressure to reduce elephant populations in many reserves. Quantitative data on the impact of elephants on invertebrates, the main component of biodiversity at the species level, are lacking. The aim of this project was to assess the effect that habitat alteration by elephants has on the diversity of selected ground-dwelling invertebrates (ants, centipedes, millipedes, spiders, scorpions and termites) through the provision of logs and dung as a potential refuge niche for these invertebrate communities, and to determine the effect of spatial (vegetation types) and temporal (season and age of dung) variation on the invertebrates using these refugia. Variation in impacts was considered important because savanna is not homogenous and the impact of the refugia is likely to be dynamic in terms of seasonal trends in invertebrate populations, and in terms of changes in the environmental conditions offered by the refugia. Elephant impact on vegetation, quantity of refugia (logs and dung) produced and invertebrate diversity associated with refugia were determined for 115 transects within Madikwe Game Reserve in the North Western Province, South Africa. Invertebrate abundance, species richness and diversity were always higher under refugia than in areas without refugia. Vegetation utilisation, frequency of refugia production and invertebrate diversity showed strong temporal variation (seasonal); elephant impact and production of logs were higher in winter than in summer because elephants are more likely to feed on woody vegetation in winter when grass nutrient levels are low. Invertebrate diversity under the logs was higher in summer than in winter, and this probably reflected the higher abundance and diversity of invertebrates that are usually associated with the warmer, wetter summer months. The effect of adding refugia to three vegetation types on invertebrate diversity was tested experimentally at Makalali Private Game Reserve in the Limpopo Province, South Africa. Logs and elephant dung were set out in five plots each measuring 20m x 20m within Govender - iii mixed bushveld, riverine and mopane woodland. Significant differences were observed in invertebrate abundance, species richness and diversity between the refugia and control plots that lacked refugia and between the three vegetation types sampled. Similarity between invertebrate communities utilising the different refugia types and between the three different vegetation types were tested using the Jaccard similarity coefficient. The three vegetation types shared fewer than 50% of their species, as did the logs, dung and control sites. However the results obtained do illustrate a higher degree of similarity between the refugia substrates (logs and dung) than the control sites and between the more heterogeneous vegetation types (mixed bushveld and riverine) than the mopane veld. This indicated that invertebrate communities associated with refugia were not uniform, but were influenced by vegetation type. An experimental test of temporal changes in invertebrate community composition illustrated the importance of elephant dung as a microhabitat for different invertebrate groups over different ages of dung (three days, two, four, 12 and 32 weeks old). Colonisation of the dung, by dung beetles was immediate but as the microclimate of the dung changed with time, the new conditions were ideal for other invertebrate taxa. Over a period of eight months, the change of invertebrate communities utilising the dung included dung beetles, followed by millipedes and [mally ant and termite communities. The results of this study illustrated the importance of refugia (logs and dung) produced by elephants for ground-dwelling invertebrate species in the savanna environment. The extent of the influence of the refugia varied both spatially and temporally and this should be considered in future monitoring or in measuring impacts. While further research on a broader range of organisms and at larger scales is necessary, elephants do have a positive impact on at least some components of biodiversity, through the process of facilitation of refugia. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

The biology of the Grey-headed Gull was studied between 2004 and 2005 in South Africa's Gauteng, KwaZulu-Natal and Northern Cape provinces. Grey-headed Gulls have a widespread but patchy distribution in South Africa, occurring both inland and at the coast. Their largest population is centred on Gauteng, where the species appears to be a relatively recent colonizer and where the current breeding population is estimated at 2185 breeding pairs (the largest in South Africa). There is evidence that the species has also increased in other parts of South Africa, especially at Port Elizabeth in the Eastern Cape. The majority of coastal birds are found in KwaZulu-Natal and there is strong evidence for regular movements of adult birds between Durban and Lake St Lucia. By contrast, little evidence was found for a putative large-scale, regular movement between Gauteng and KwaZulu-Natal. The breeding biology of the Grey-headed Gull was studied at four sites in Gauteng and at Lake St Lucia's Lane Island during 2004 and 2005. The distance between the Gauteng sites ranges from 1.7 km, between Lakefield Pan and Korsman's Bird Sanctuary, to 25.3 km, between Bonaero Park and Modderfontein Pan. The approximate distance between Gauteng and Lake St Lucia is 460 km. The mean clutch size at all sites was 2.42 eggs and the mean incubation period was 24.9 days. Parental investment in incubation was approximately equal between the sexes while males spent more time in attendance and participated in more aggressive encounters. Empirical growth curves are given for mass, wing, culmen, head and foot morphometrics of Grey-headed Gull chicks. Intraspecific variation in breeding parameters reveal significant differences between sites, including: highly synchronous laying at Lake St Lucia; the largest eggs and fastest growing chicks at Gauteng's Modderfontein Pan (a small, peripheral colony); and the smallest eggs and slowest growing chicks at Gauteng's Lakefield Pan (a large, 'core' colony). Possible reasons for these differences include the relative localities of each site in terms of feeding opportunities, high levels of predation by African Fish Eagle's at Lane Island, and density dependent factors operating on the large colonies within the core population on Gauteng's East Rand. Overall daily egg survival was comparatively high for all sites in Gauteng and low for Lane Island nests. Morphometric, plumage and bare-parts data from a sample of trapped and resighted birds are used to age, sex and determine the timing and duration of moult in the Greyheaded Gull. Six age classes were identified and, for all measurements, males were significantly larger than females. The mean duration of primary moult was 136 days between October and January and there were two waves of secondary moult. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

South Africa is one of the world's most biologically invaded countries and has spent billions of rands on efforts to eradicate alien invasive plants. Chemical and mechanical control methods have varied in success and the need for integrated management strategies has been realised. This requires a better understanding of all aspects of the invasion process. Some of the most invasive plant species rely on vertebrate dispersers which facilitate long-distance seed dispersal. Frugivory is based on a mutualism in which the frugivores gain a resource and the plants benefit from seed dispersal away from the parent plant. Seed germination itself may either be enhanced, reduced or not affected at all after gut passage. The first aim of this study was to determine if generalist avian frugivores and a fruit bat species (Epomophorus wahlbergi) enhance or decrease seed germination of invasive alien plants in South Africa, by either pulp removal or seed coat abrasion, or if they serve as dispersers only. The second aim was to determine if avian frugivores are able to meet their energetic demands by feeding on a specific alien fruit diet. Finally, we also quantified the nutritional content and morphological characteristics of fleshy fruits of various invasive alien and exotic plant species. Avian frugivores: Red-winged Starlings (Onychognathus morio), Speckled Mousebirds (Colius striatus), and Dark-capped Bulbuls (Pycnonotus tricolor), varied in their effects on the germination success of seeds of four invasive alien species, namely: Lantana camara, Solanum mauritianum, Cinnamomum camphora, and Psidium guajava. However, this was not associated with differences in seed retention times. Similar germination success was observed for avian ingested and de-pulped seeds. This was also observed for fruit bat spat and depulped seeds of Psidium guajava, Melia azedarach, Eriobotrya japonica, and Morus alba. Therefore seed coat abrasion was not important for the germination of these fleshy-fruited invasive alien plants. Pulp removal resulted in significantly earlier seed germination as well as higher seed germination percentages than in the case of whole fruit controls for some of these invasive species. Gut passage is thus important for long-distance dispersal, and in some cases, for enhanced germination of seeds. The invasive Solanum mauritianum and indigenous congener S. giganteum showed similar germination responses, with both ingested and depulped seeds germinating profusely. However, S. giganteum benefited from pulp removal as seeds from whole fruits had less germination. Avian frugivores varied significantly in most energetic parameters calculated when given diets of invasive alien fruit. Speckled Mousebirds and Dark-capped Bulbuls were able to maintain body mass and efficiently process fruits of all four alien invasive plants, while Red-winged Starlings were only able to do so on lipid-rich C. camphora and sugar-rich S. mauritianum. Furthermore, frugivores also adjusted their feeding behavior by eating more nutritionally poor fruit and less energetically rewarding fruit. Fruit bats consumed more fruit per gram body mass than avian frugivores did. They therefore process proportionately more seeds than avian dispersers and thus their role in invasive seed dispersal, which has previously been underestimated particularly in South Africa, is highlighted. Fruits of invasive plant species were similar in morphology, but greater in nutritional content, than fruits of indigenous species. These fruits also contained small, light seeds with approximately only 30% having more than 10 seeds per fruit. The ability of frugivores to efficiently process these fruits and the greater nutritional rewards offered by these provide new insights into why these invasive fruits are preferred by frugivores. In addition, invasive alien plants may have a competitive edge over indigenous species because of their larger reproductive outputs and not necessarily because of greater germination success. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

In general Nile Crocodile Crocodylus niloticus numbers in South Africa appeared to have recovered after persecution and eradication attempts during the last century. Within the last decade, however, the future of South Africa’s Nile Crocodiles seems ominous yet again, as they are faced with renewed threats including habitat destruction and/or degradation. The primary Nile Crocodile populations in South Africa, Kruger National Park, Lake St Lucia and Ndumo Game Reserve are all currently threatened as a result of anthropogenic actions. The vulnerability of South Africa’s major Nile Crocodile populations has highlighted the need for further studies on and assessment of other populations in the country. This study was conducted from April 2009 to July 2010 on the Nile Crocodile population found in Pongolapoort Dam. The aim of the study was to obtain baseline data on the ecology of this previously unstudied population, which included obtaining an estimate of population size and structure, the reproductive dynamics and success of the population, general distribution of the population in the dam and seasonal changes in their distribution. The impact of the impoundment on this population was also discussed. Initial surveys from 1981 and 1989 described few crocodiles in the system. Currently Pongolapoort Dam contains a significant Nile Crocodile population that was previously not considered as substantial. A conservative estimate of 273 Nile Crocodiles was determined for Pongolapoort Dam in 2009-2010. A combination of survey methods allowed for a population structure to be gauged and identified as having 116 juveniles (< 1.2 m), 75 sub-adults (1.2 - 2.5 m), and 82 adults (> 2.5 m). Currently the population has a high percentage of juveniles (42 %), suggesting a growing population, with the proportion of adults (30 %) able to sustain a viable population into the future. From the construction of the Pongolapoort impoundment in 1972 the water level has fluctuated and the surrounding landscape has been altered. As a result the Nile Crocodiles residing in the area had to adapt to the ever changing environment. Their general distribution changed after dam wall completion, when the dam began to fill. First distributional change was a movement out of the gorge section into the newly flooded areas. After the Domoina floods (1983) the dam level rose by over 70 % and the crocodiles moved into the current inlet section. The majority of the crocodile population is now found in the inlet section of the Pongolapoort Dam, utilizing the Phongola River in summer months and residing in the inlet section as historical basking sites during the winter months. Investigating reproductive ecology is essential in order to access the population dynamics of an unstudied population, as reproductive output can be a measure of population health. Reproduction and nesting of Nile Crocodiles in Pongolapoort Dam, and in particular determining the effects of the impoundment on these were investigated. No previous reproductive effort had been documented prior to this study. Crocodiles congregated at a major basking site, where the Phongola River entered the dam, during August 2009 with a 576 % increase in numbers. This signalled the commencement of the breeding season. Females with transmitters made short trips upstream during this time. In November, with the first rains, the river rose and the majority of crocodiles moved up the inlet, and females established nests. Three major nesting areas were identified, two of which were located in the river inlet to the dam. Approximately 30 nesting females were identified during the 2009/2010 nesting season. All nesting areas identified had been used in prior nesting seasons. Nests were located on a variety of substrate types, from clay formed through culluvial and fluvial deposits to course river sand. Several of the nests were predated by Water Monitor (Varanus niloticus). Although the number of nesting females was greater than expected, during the study period there was a total recruitment failure of nests along the river due to a flash flood of the Phongola River in January 2010, destroying all nests prior to hatching. As several juvenile crocodiles were found during surveys, this preliminary study suggests that the Pongolapoort Dam Nile Crocodile population has a relatively high potential reproductive out-put, although their annual successes may vary greatly because of loss of nesting sites because of water level fluctuations and predation. It appears that the impoundment has generally had a positive impact on this Nile Crocodile population recruitment although suitable nesting sites may become limited. There appear to be no current threats to the Nile Crocodile Pongolapoort Dam population, however illegal gill-netting and poaching on the dam and surrounding reserves is on the rise and if not prohibited can result in future problems. A second concern is the high abundance of alien invasive plants that dominate the area, most notably in the river inlet section, the Nile Crocodiles main nesting area. The water quality entering the system is unknown at present and should be tested in future studies to assess whether there may be any reason for concern. In general the Nile Crocodile population in Pongolapoort Dam appears to be one of the least vulnerable and most reproductively successful in South Africa at present. The population has increased dramatically as a result of successful reproductive output even with the ecosystem changes as a result of the impoundment of the Phongola River. It is unlikely that the population increase was as a result of immigration from surrounding areas as the dam wall is a substantial barrier between the dam and the lower crocodile population of Ndumo Game Reserve some 70 km downstream. The high number of crocodiles found through all size classes, juveniles to large adults, also suggests that this population has been stably increasing for a number of years and has a sustainable breeding population. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Meyer’s Parrot Poicephalus meyeri is the smallest of the nine Poicephalus parrots, forming the P. meyeri superspecies complex with five congeners. Their distributional range far exceeds any other African parrot, extending throughout subtropical Africa. Meyer’s Parrots had previously not been studied in the wild, and therefore, gathering high-quality empirical data on their behavioural ecology became a research and conservation priority. The primary aim of the study was to correlate environmental (e.g. rainfall, habitat availability, resource characteristics, food resource abundance and temperature) and social (e.g. inter- and intra-specific competition, predation, and human disturbance) variables with aspects of their ecology (e.g. flight activity, food item preferences, breeding activity, and group dynamics) to evaluate the degree of specialization in resource use (e.g. trophic, nesting and habitat niche metrics). African deforestation rates are the highest in the world, resulting in twelve out of the eighteen Meyer’s Parrot range states undergoing drastic loss of forest cover over the last 25 years. Most commentary on the population status of Meyer’s Parrots and other Poicephalus parrots pre-dates this period of rapid deforestation In addition, over 75 000 wild-caught Meyer’s Parrots and almost 1 million wild-caught Poicephalus parrots have been recorded in international trade since 1975. Empirical data from this study was used to identify ecological weaknesses (e.g. niche specialization or low breeding turnover) for evaluation within the context of deforestation in the African subtropics. Baseline data on the breeding biology and nest cavity requirements of Meyer’s Parrots was also necessary to assess the viability of applying the conservative sustained-harvest model to African parrots. A unifying goal of this study was to advance our knowledge of the ecology of African parrots and other Psittaciformes by assessing the validity of current hypotheses put forward in the literature. The Meyer’s Parrot Project was initiated in January 2004 on Vundumtiki Island in the north-eastern part of the Okavango Delta, Botswana. Due to high flood waters between March and July 2004, road transects were postponed till August 2004. Transects were conducted at Vundumtiki from August 2004 to July 2005 and February 2007 to August 2007, and at Mombo from August 2005 to January 2006. During 480 road transects over 24 months, food item preferences closely tracked fruiting and flowering phenology, resulting in significant positive correlations between Levins’ niche breadth, rainfall and food resource availability. Meyer’s Parrot can, therefore, be considered opportunistic generalists predispersal seed predator that tracks resource availability across a wide suite of potential food items, including 71 different food items from 37 tree species in 16 families. Meyer’s Parrots were, however, found to be habitat specialists preferring established galleries of riverine forest and associated Acacia-Combretum marginal woodland. These strong habitat associations facilitate their wide distribution throughout the Kavango Basin, Linyanti Swamps, down the Zambezi valley, up along the Rift Valley system in associations with the great lakes, through the Upper Nile and the Sudd, and west as far as Lake Chad through the Sahel. Seventy-five nest cavities were measured during this study, including 28 nest cavities utilized by Meyer’s Parrots within the 430ha sample area at Vundumtiki. Over 1700 hours of intensive nest observations at six nest cavities was undertaken. Meyer’s Parrots formed socially monogamous pair-bonds maintained over at least four breeding seasons. Breeding pairs established breeding territories up to an estimated 160ha within which there were 1–6 nest cavities. Eggs hatched asynchronously, yet nestlings fledged synchronously with similar body size and condition. There was evidence to support the incidence of extra-pair copulations, however, mitochondrial DNA sequence data are required to confirm the incidence of extra-pair fertilizations. Meyer’s Parrots had no preferences in regard to nest tree species beyond the incidence of suitable nest cavities, which are selected and further excavated to accommodate their non-random nest cavity preferences. There was a significant non-nesting Meyer’s Parrot population during the breeding season, likely due to this longlived cavity-nester delaying nesting until a suitable breeding territory becomes available. Meyer’s Parrots utilize communal roosts during summer and disperse from them according to the Foraging Dispersal Hypothesis. Due to the requirement to roost during the middle of the day to avoid heat stress, Meyer’s Parrots have bimodal flight and feeding activity patterns. The highest probability of locating Meyer’s Parrots is between 08h30 and 11h00 during summer when both adults are feeding on the seeds of fleshy-fruits in riverine forest communities. Due to the paucity of data on the current distribution and population status of Meyer’s Parrots and other African parrots, a continent-wide survey of all African parrots represents a conservation priority. Current deforestation rates in several Meyer’s Parrot range, their specialist habitat associations, and lack of evidence to support adaptability to a changing landscape mosaic necessitate the re-classification of Meyer’s Parrots as data deficient or nearthreatened. Based on low breeding population due to limited breeding opportunities, the CITES Appendix II wild-caught bird trade should also be halted until the sustainability of this trade has been evaluated and the relevant information made available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Thesis (MSc)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Evidence for widespread ecological impacts due to rapid climate change is on the increase, with further warming predicted over the next century. This increase in warming has lead to organisms adjusting their distribution range and where this is not possible organisms must cope with the stressful environments in a different way. One potential way to handle environmental stress is via a mechanism known as phenotypic plasticity, which allows an organism to express different phenotypes depending on the biotic or abiotic environment in a way that may alter that organism's fitness. Acclimation temperatures can potentially cause plastic (reversible and irreversible) changes in the response of individuals to stressful experimental conditions that could increase their survival. The issue of whether this acclimation will be beneficial to the organism or not remains contentious, with support offered both for and against the idea of beneficial acclimation. The aims of the investigation were to determine the thermal limits of five ameronothrid mite species (Halozetes marinus, H marionensis, H belgicae, H. fulvus and Podacarus auberti) from varying terrestrial habitats and to test whether there is beneficial acclimation on the thermal traits. Along with the beneficial acclimation hypothesis several alternative hypotheses were also tested. In addition, locomotor performance was determined as it has been suggested that locomotion performance is a reliable and practical measure of potential fitness of animals. The same hypotheses testing the effects of acclimation temperature on the thermal limits were tested on three performance traits; performance breadth, optimum speed and optimum temperature. Support for beneficial acclimation was found in the performance breadth and optimum speed traits for all species except for Halozetes marinus. For the optimum temperature trait the prediction for the compensation hypothesis was met and that of the beneficial acclimation hypothesis rejected, with the only exception again being that of H marinus. In the case of the locomotor performance traits the prediction for the beneficial acclimation hypothesis in the performance breadth and optimum speed traits are the same for that of the compensation hypothesis, therefore the overall response of the more terrestrial mite species is one of compensation. However, support for beneficial acclimation was not found in the thermal limit traits of all five species, with the higher acclimation temperatures (specifically 150 C) resulting in negative responses in LLT in H. marinus and H. belgicae, and in ULT in H. fulvus. Phenotypic flexibility varied between marine and terrestrial species. The less variable marine environment showed lower flexibility than that of terrestrial species in the performance breadth trait and optimum temperature trait, but there was a lack of variation between the marine and terrestrial species in the temperature tolerance traits. These results show that the effects of acclimation on various traits, especially fitness related traits, are complex and require more attention if the consequences are to be fully explained. This study therefore provides insight into the effects of acclimation on performance traits and thermal limit traits and has implications for the evolution of plastic responses in terrestrial arthropods. / AFRIKAANSE OPSOMMING: Bewys vir wye ekologiese impakte as gevolg van vinnige klimaatsverandering is aan die toeneem, met verdere verwarming wat voorspel word gedurende die volgende eeu. Dié toename in verwarming het alreeds veroorsaak dat organismes hulle verspreidings verander, of waar dit nie moontlik is nie, moet hulle stresvolle omgewingstoestande op 'n ander wyse hanteer. Een moontlike manier om omgewingsstres te hanteer is deur gebruik te maak van 'n meganisme wat bekend staan as fenotipiese plastisiteit, wat dit vir 'n organisme moontlik maak om ander fenotipes te toon afhangende van die biotiese of abiotiese omgewing in 'n wyse wat die organisme se fiksheid beinvloed. Temperatuur akklimasie kan moontlik plastisiteit (omkeerbaar of onomkeerbaar) veranderinge in die reaksie van individue tot stresvolle eksperimentele toestande tot gevolg hé, wat gevolglik hulle oorlewing kan verhoog. Die kwessie of hierdie akklimasie wel voordelig vir die organisme is of nie is steeds betwisbaar, met beide steun vir en teen die idee van voordelige akklimasie. Die doel van hierdie ondersoek was om vas te stel wat die termiese limiete van vyf ameronothrid myt spesies (Halozetes marinus, H marionensis, H belgicae, H fulvus en Podacarus auberti) van verskeie terrestriële habitatte is, en om te toets of daar voordelige akklimasie in die termiese eienskappe voorkom. Tesame met die voordelige akklimasie hipotese is daar verskeie alternatiewe hipoteses ook getoets. Verder, is bewegings prestasie vasgestelomdat dit al voorgestel is dat bewegings prestasie 'n betroubare en praktiese mate van die potensiële fiksheid van 'n dier aantoon. Dieselfde hipotese wat die effek van akklimasie temperatuur op die termiese limiete toets, is op drie prestasie eienskappe getoets; prestasie wydte, optimale spoed en optimale temperatuur. Bewyse vir voordelige akklimasie is gevind in die prestasie wydte en optimale spoed eienskappe vir alle spesies behalwe Halozetes marinus. Vir die optimale temperatuur eienskap was die voorspelling vir die kompensasie hipotese korrek maar dié van die voordelige akklimasie verkeerd, met H. marin us die enigste uitsondering. In die geval van die bewegings prestasie eienskappe is die voorspelling vir die voordelige akklimasie hipotese in die prestasie wydte en optimale spoed eienskappe die selfde as vir die kompensasie hipotese. Daarom is die algemene reaksie vir die meer terrestriële spesies een van kompensasie. Bewyse vir voordelige akklimasie is egter nie gevind in die termiese limiet eienskappe van die vyf spesies nie, met die hoér akklimasie temperature (spesifiek 15° C) wat 'n negatiewe reaksie in LLT in H. marin us en H. belgicae, en in UL T in H. fulvus veroorsaak het. Fenotipiese buigsaamheid het verskil tussen mariene en terrestriële spesies. Die minder variërende mariene omgewing het 'n laer buigsaamheid in die prestasie wydte en optimale temperatuur eienskappe getoon as die van terrestriële spesies, maar daar was geen variasie tussen mariene en terrestriële spesies in die temperatuur toleransie eienskappe nie. Die resultate wat hier voorgelê word wys dat die gevolge van akklimasie op verskeie eienskappe, veral fiksheids verwante eienskappe, ingewikkeld is en vereis meer aandag om die gevolge volledig te verduidelik. Hierdie studie verskaf dus insig in die gevolge van akklimasie vir prestasie eienskappe en termiese limiet eienskappe en het gevolge vir die evolusie van plastiese reaksies in terrestriële arthropoda.