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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Systematic revision of the golden mole genera : Amblysomus, Chlorotalpa and Calcochloris (Insectivora : Chrysochloromorpha ; Chrysochloridae)

Bronner, Gary N. January 1995 (has links)
Patterns of variation in hyoid morphology, chromosomal properties and craniodental characteristics among ten chrysochlorid species from South Africa were studied to clarify generic relationships among taxa assigned variably to Amblysomus, Chlorotalpa and Calcochloris by previous authors. Intra-specific variation in hyoid morphology was negligible, but inter-specific differences were marked. Similarly, intra-specific karyotypic variation was negligible, except in A. hottentotus, which displayed three cytotypes. These data supported the recognition of Chlorotalpa, Calcochloris and Neamblysomus as taxa distinct from Amblysomus. Only one (presence/absence of M3) of the seven dental traits used by previous authors was consistent enough within species to be taxonomically useful in this work. Dental variability within species appeared to arise from the morphological differences between deciduous and permanent teeth, which may occur together in the same toothrow. Intra-specific craniometric variation in most species involved pronounced sexual size dimorphism, but negligible age-related variation. In the more widespread species, patterns of geographic variation were dominated by divergence in overall size, although subtle differences in cranial shape were also evident. Multivariate analyses confirmed the validity of subspecies in Chlorotalpa sclateri and Calcochloris obtusirostris, and showed that A. hottentotus (as traditionally recognized) includes: four cryptic species; five subspecies (including A. h. iris); and several populations that should be relegated to A. corriae. Inter-specific morphometric variation was dominated by overall size. The species fell into two size groups, and eight phena that differed mainly in skull width, palatal shape, rostrum breadth and claw size. Inter-specific relationships suggested by phenetic analyses of metric and mixed-mode data were, however, incongruent owing to discordance between different data suites. Evolutionary relationships inferred by integrating data suites, using either equal or differential weights, indicated that a strong phylogenetic signal was present in the data. Phylogenetic analyses showed that the differentially weighted treatment was more consilient with character-state distributions. A phylogram based on the differential-weights cladogram was used to derive a revised phylogenetic classification for the Chrysochloridae. Unlike previous treatments, this classification affords Carpitalpa and Neamblysomus generic rank, and assigns C. leucorhina from equatorial Africa to Calcochloris, rather than to Chlorotalpa. / Thesis (Ph.D.)-University of Natal, 1995.
2

The ecological implications of sea-level rise and storms for sandy beaches in KwaZulu-Natal.

January 2008 (has links)
The aesthetic appeal of beaches has made coastal properties prime sites for development. However, this development has been mismanaged and is within the littoral active zone. Beaches retreat landwards as sea levels rise, but with current development trends, beaches are trapped in a coastal squeeze. Climate-change predictions include an increase in frequency and heightened intensity of storms, which can cause significant erosion. This study aimed to determine the ecological implications of sea-level rise and storms for beaches in KwaZulu-Natal (KZN), using geographic information systems (GIS) and beach sampling methods. The beaches were mapped in terms of physical and biological attributes. Spatial trends in these attributes showed that the coastline can be split into three – the northern, central and southern regions. Although 25 % of the coastline is protected by marine reserves, these are located in the Delagoa bioregion: 28 macrofauna species in the Natal bioregion are not protected. Storm impacts for beaches can be heterogeneous, depending on local coastal features, e.g., nearshore reef and sand dunes, and represented a temporary disturbance to macrofauna communities. A GIS-based coastal recession model was derived from Bruun’s rule, and applied for different scenarios of sea-level rise and coastal development. Coastal squeeze is concern, particularly in the southern region. Further, the 10-m elevation contour was not completely effective as a setback line, even for a low sea-level rise scenario. The coastal recession model was validated using data from a real event in KZN, where sea level rose temporarily by ~1.0 m. The model performed well, although the calibration possibly did not span a wide enough range of beach morphodynamic types, and under-predicted retreat for dissipative beaches. It was concluded that the Natal bioregion needs marine reserves, and that higher resolution spatial data are required for accurate beach modeling and the south coast railway line should be relocated proactively. Guidelines for sandy beach systematic conservation planning were outlined, and seated in a conceptual framework of managing beaches for resilience. Application of the proposed recommendations and frameworks could aid in determining a way forward in integrated coastal zone management for KZN, in the face of the uncertainties associated with climate change. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.
3

Detecting parasites loads in urine diversion toilets.

Hawksworth, David James. January 2009 (has links)
In an attempt to supply sanitation to the growing communities in rural and peri-urban areas around Durban, the eThekweni Municipality has installed urine diversion (UD) toilets which have been modified to suit local conditions . These toilets are based on the ecological sanitation (EcoSan) system. The future aims are to reuse waste as a composting medium and minimize the use of water but the presence of microorganisms in the faecal waste poses a potential health risk to people in contact with it. Currently the Municipality has not deemed the waste safe for re-use but has suggested that after a one year standing period it should be free of all potential pathogens including Ascaris lumbricoiodes (human roundworm) ova. This study reports on the development of the AMBIC protocol for the recovery of Ascaris ova from the standing vaults of UD toilets. The protocol has been shown to consistently recover over 70% of Ascaris ova and has the added advantage of recovering the ova of other helminth species (Trichuris trichiura and Taenia sp.) present in a UD standing vault sample. Recoveries of Ascaris ova and ova of other parasite species, namely Trichuris and Taenia sp., are reported from waste which has been standing for one year. This is cause for concern as it shows one year is not a sufficient standing period to render the waste free of all microorganisms. Sampling from 124 UD toilet vaults that were in use, showed a high prevalence of both helminth (Ascaris lumbricoiodes, Trichuris trichiura and Taenia sp.) and protozoan (Giardia and Cryptosporidium) parasites. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.
4

The relative influence of local and landscape processes on the structure of insectivorous bat ensembles in urban nature reserves.

Moonsamy, Shivani. January 2012 (has links)
Urbanization is arguably the most damaging and rapidly expanding threat to biodiversity. The process of urbanization results in the fragmentation of natural habitat into patches that are disjunct and isolated from one another. Biogeography theory predicts that landscape processes, including fragment size and isolation, should predominate in species assembly. However, these predictions have not been tested on African bats in urban landscapes. Bats are important models for urban studies because they comprise more than a fifth of all mammals, and play vital roles as primary, secondary and tertiary consumers that support human-dominated ecosystems. Furthermore, there is evidence that local, biotic processes specifically competition and prey defences are important determinants of species composition patterns. In this study, I investigated the relative influence of local and landscape processes on the species composition patterns of insectivorous bat ensembles in Durban. Using active capture methods and passive monitoring, I sampled the insectivorous bat ensembles of eight nature reserves in Durban between 2008 and 2010. I used multivariate analyses to test predictions from biogeographic and climate hypotheses, and I used null model analyses to test predictions from competition and nestedness hypotheses to determine whether the bat richness patterns were significantly different from patterns expected by chance. Species richness estimators indicated that species inventories for ensembles were fairly complete (i.e. estimated species richness was not much larger than observed species richness). Multiple regression analyses showed that there was a significant parabolic relationship between species evenness and daily maximum temperature, and there was a significant negative relationship between relative activity and reserve shape. However, I found no evidence that competition influenced species composition patterns. Conversely, I found support for the nestedness hypothesis: species in species-poor ensembles were subsets of species in species-rich ensembles. Spearman rank correlation indicated that the degree of nestedness was significantly correlated with maximum temperature. My results suggest that in urban landscapes, abiotic processes operating at the landscape scale may be more important determinants of composition patterns of insectivorous bat species than biotic factors operating at a local scale. Furthermore, bat species that forage in cluttered habitats may not be able to persist in urban landscapes. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.
5

Connectivity of two scleractinian corals in the south west Indian Ocean.

Macdonald, Angus Hector Harold. January 2010 (has links)
Generations of hard corals have built the complex reef ecosystems that harbour a huge diversity of sea-life in the world’s shallow tropical oceans. These undergo both sexual and clonal reproduction, and may contain signatures in their genomes which help to decipher the riddles of past population dynamics and evolutionary history. Two species of coral, Acropora austera and Platygyra daedalea, were collected from sites along the east African coastline from Kenya in the north to Maputaland, South Africa in the south, and from the Chagos Archipelago. Sequences of two different DNA regions were tested, in a preliminary study, for their potential ability to elucidate connectivity and differentiation among these coral populations. These were the nuclear ribosomal ITS region of P. daedalea populations, and a previously-unused marker, the carbonic anhydrase 3/550 nuclear intron of A. austera. These molecular markers indicated high levels of connectivity amongst populations in a preliminary study based on limited sample sizes and a subset of populations. It was decided to further explore the variability of the carbonic anhydrase 3/550 intron, which showed evidence of subdivision and structuring within Mozambique populations relative to South African populations, in a study in which both the sample size per site and the number and range of sampled sites were increased. ITS sequences, although highly variable, revealed no population differentiation in P. daedalea; STR markers were used in subsequent studies of population differentiation in this species. Populations of both A. austera and P. daedalea showed signs of high connectivity along the region of the coastline sampled in this study. However, there appeared to be a disjunction in ecological connectivity between reefs in Maputaland, South Africa and those in southern Mozambique, between Durban and Maputo where the Agulhas Current originates. This was reinforced in A. austera populations which displayed a region of genetic discontinuity between Inhaca Island and Maputaland reefs of the central reef complex, in the region of Rabbit Rock. Northern reef complexes also harboured unique haplotypes in contrast to southern reefs which shared all haplotypes with those in the north, an indication that northern reefs have seeded the southern (Maputaland) reefs. P. daedalea populations appeared evolutionarily panmictic over scales relevant to this study. Evidence for fine-scale structure indicated that populations were separated from one another over ecologically relevant time-scales. These populations were defined by both their habitats and their sampling location. There was a possibility that the Platygyra species complex included cryptic species that were not distinguishable from P. daedalea. However, the disjunction in the connectivity between northern and southern population groups was also evident in the population structure of P. daedalea. There was a net immigration of propagules of both P. daedalea and A. austera into populations north of the disjunction between groups, where the prevailing current regime is dictated by the Mozambique Channel eddies. In contrast populations to the south of the disjunction (the southern population group) which are subject to the swiftly flowing Agulhas Current, showed a net emigration of propagules from Maputaland reefs. These emigrants were likely to be lost to inhospitable habitat south of the marginal Maputaland region. Although there was evidence for migration of both Platygyra and Acropora propagules between the Bazaruto Archipelago reefs and certain Maputaland reefs, genetic exchange between Mozambique and Maputaland reefs appeared to be limited and may have occurred primarily at evolutionary rather than demographic levels. Managers may need to treat the regional Maputaland reefs as separate stocks and manage them accordingly, as the relative isolation of these corals in the central and southern reef complexes in Maputaland, South Africa, means that they are at risk to losing species to evolutionary extinction. It is also important that reef health in northern Mozambique and Tanzania is maintained as, despite evidence of a break in demographic connectivity, between reefs in these regions and those in Maputaland, there was evidence to suggest that reefs were connected at evolutionary scales, thus maintaining levels of genetic diversity on southern African reefs. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.
6

The effects of elephant and mesoherbivores on woody vegetation.

Lagendijk, Daisy Diana Georgette. January 2011 (has links)
Herbivores are important drivers and have a longstanding history in shaping our terrestrial environments. However, during the past decades, changes in woody vegetation in savanna and forest systems have been observed in southern Africa. Subsequently, concerns have been raised about the loss of (tall) trees in areas with elephant. The relative effects of browsing herbivores on vegetation and the potential browsing interaction with other herbivore species remain unclear and were examined using vegetation transects and exclosure experiments in savanna woodland and Sand Forest. Rainfall, fire and elephant were important savanna determinants. Especially rainfall positively affected woody densities, which were negatively affected by a longer exposure time to elephant, but not to elephant densities itself. In general, within South Africa’s savannas, tree height classes were absent from the population demography. Different height classes were likely to be impacted by different drivers. For example, seedling and sapling densities were greater with longer fire return periods and increased rainfall. The Sand Forest exclosure experiments showed that forest regeneration was impacted by nyala and both elephant and nyala, as the absence of both species increased tree densities. Both species combined, and individually, also affected tree species assemblages. In contrast, short term elephant access to a savanna area did not affect tree densities or species assemblages. In both savanna and Sand Forest elephant displaced mesoherbivores, and in Sand Forest both elephant and mesoherbivores displaced their smaller counterparts. The presence of competitive displacement also affected recruitment (i.e. seedlings and/or saplings) of woody vegetation both in Sand Forest and savanna. Thus, elephant and mesoherbivores exert direct and indirect (i.e. competitive displacement providing a window for recruitment) impact on vegetation. Active management of the herbivore species assemblage affects both vegetation and other herbivores, which effects potentially cascade into lower trophic levels, jeopardising biodiversity and ecosystem processes. Therefore, the full herbivore assemblage present and their combined and individual browsing effects need to be considered when setting management goals to conserve habitats and biodiversity across all trophic levels. In addition some contrasting results between Sand Forest and savanna emphasise the need for caution when extrapolating results from different areas and ecosystems. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.
7

The sardine run : investigating sardine and predator distribution in relation to environmental conditions using GIS and remotely sensed products.

O'Donoghue, Sean Henry. January 2009 (has links)
The sardine run is a spectacular but poorly understood natural phenomenon. This research aims to broaden scientific knowledge pertaining to sardine, Sardinops sagax, distribution, both in relation to their predators and environmental conditions. Sardine distribution was closely related to sea temperature. Sardines were sighted every year along the Lower Wild Coast, where continental shelf conditions were cooled by the Port Alfred upwelling cell. To the north of Mbashe River, shelf conditions were dominated by the warm Agulhas Current, and sardine distribution varied annually in close relation with sea temperature conditions. Along this coastline sardine abundance always peaked between Waterfall Bluff and Port St Johns with favourable conditions caused by the westward inflection of the coastline and the shelf bathymetry. Topographically-induced upwelling was concluded to be the cause of cooler sea temperatures and elevated chl a concentrations. Although chl a concentration appeared to be associated with east coast sardine distribution, the uncertainty with regards data accuracy hindered their usefulness as a predictor of suitable biological conditions for sardine. Sardine northward movement along the KZN coastline was impeded adjacent to the Durban Eddy, where they were forced shorewards by the warm conditions. This coincided with the peak in beach seine catches. The Cape Gannet, Morus capensis, was very closely associated with sardine along the entire east coast. Their abundance declined substantially adjacent to the Durban Eddy. Prevailing atmospheric conditions affected gannet behaviour: they travelled more frequently during strong alongshore winds and foraged more upon cessation of such winds. Gannets were closely associated with feeding dolphins at both coarse and fine scales, and responded to changes in dolphin behaviour. Common dolphin, Delphinus capensis, abundance and group size peaked between Waterfall Bluff and Port St Johns. Along this stretch of coastline they travelled more slowly, and in pods more perpendicular to the bathymetry of the region. Bottlenose dolphin, Tursiops aduncus, abundance increased during the sardine run with the influx of a migrant stock which reached the KZN Mid South Coast. Humpback Whale, Megaptera novaeangliae, and sardine distributions did not appear to be related. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2009.
8

Some effects of drying rate and wet storage on aspects of the physiology and biochemistry of embryonic axes from diesiccation- sensitive seeds.

Ntuli, Tobias M. January 2004 (has links)
Desiccation-sensitive seeds show differential viability characteristics during drying at different rates. A number of studies have demonstrated that rapid dehydration permits survival to lower water contents than does slower desiccation. The aim and objective of the present study was to test the hypothesis which states that rapid drying of desiccation-sensitive seeds removes water sufficiently fast to reduce the accumulation of metabolic damage. In addition, the hypothesis that wet storage subjects desiccation-sensitive seeds to mild, but increasingly severe, water stress causing oxidative damage if additional water is not supplied, was tested. In the present study, axes of germinating orthodox seeds of Pisum sativum and newlyshed recalcitrant counterparts of Quercus robur, Strychnos madagascariensis, Trichilia emetica, Trichilia dregeana and Avicennia marina were subjected to rapid or slow drying or wet storage. For those species where more than one harvest was investigated, differences were observed in water contents at shedding. For all the species studied, the dehydration rate could be described by an exponential and a modified inverse function for both desiccation regimes, and the water content remained constant with wet storage. The level of tetrazolium staining and germination percentage of axes decreased sharply drying and hydrated storage such that the marked decline took place at lower water contents upon rapid than slow dehydration. The conductivity of electrolyte leachate increased progressively during desiccation and moist storage of axes of all species investigated. Greater membrane leakage occurred upon slow, than rapid dehydration in axes of all species studied. Activities of respiratory enzymes which have a potentially regulatory role in glycolysis, phosphofructokinase (PFK), or the tricarboxylic acid cycle, malate dehydrogenase (MDH), and levels of the oxidized form of the coenzyme, nicotinamide adenine dinucleotide (NAD), of the enzymes of the electron transport chain, NADH dehydrogenases ofNADH-ubiquinone (coenzyme Q) reductase (complex I) and NADHcytochrome c reductase (complex IV), were monitored in the present investigation. v In addition, the role of free radical activity in the form of lipid peroxidation, which has been implicated in loss of viability in seeds, was examined by assaying the levels of hydroperoxides. The involvement of the free radical processing enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), and the antioxidant, ascorbic acid (AsA), was also ascertained. The activity of PFK in axes of P. sativum remained constant during drying and wet storage. However, PFK activity increased as rapid dehydration and hydrated storage of Q. robur axes proceeded. In contrast, the activity of PFK in axes of Q. robur decreased during slow desiccation. Similarly, PFK activity was reduced upon drying, and moist storage, of T. dregeana axes such that higher activity of PFK was seen during rapid than slow dehydration. The activity ofPFK inA. marina axes also declined upon desiccation. The activity ofMDH in axes of P. sativum was also unchanged during drying and wet storage. However, an increase in MDH activity was recorded in Q. robur axes during dehydration and hydrated storage such that the activity of MDH was higher upon slow than rapid desiccation. In contrast, MDH activity in axes of T. dregeana decreased as drying proceeded. Similarly, the activity of J\.1DH declined during dehydration and moist storage of A. marina axes. An increase in the level of NAD occurred in axes of P. sativum during drying. In contrast, a decrease in NAD levels was seen upon dehydration and wet storage of Q. robur axes such that the level of NAD was higher upon rapid than slow desiccation. There was an enhancement of the level of NAD in axes of T. dregeana during hydrated storage. Conversely, NAD levels declined during drying ofA. marina axes. A decrease in the level of hydroperoxides in axes of P. sativum was seen as rapid drying proceeded. In contrast, hydroperoxide levels increased during wet storage of P. sativum axes. Similarly, the levels of hydroperoxides were enhanced upon dehydration and hydrated storage of Q. robur axes such that they were higher in axes during slow desiccation compared to those dried rapidly. Conversely, the hydroperoxide level in axes of T. dregeana was reduced upon rapid dehydration. In contrast, an elevation of the level of hydroperoxides was observed during moist storage. The levels of hydroperoxides remained constant as desiccation and wet storage ofA. marina axes proceeded. vi The activity of SOD in axes of P. sativum decreased during rapid drying. In contrast, SOD activity increased upon slow dehydration and wet storage ofP. sativum axes. There was a decline in the activity of SOD in Q. robur axes during slow desiccation. Similarly, SOD activity was diminished upon drying of axes of T. dregeana. The activity ofSOD in T. dregeana axes was enhanced during hydrated storage. An elevation in SOD activity also took place during rapid dehydration and moist storage of axes ofA. marina. The activity of CAT did not change during drying of axes of P. sativum. However, a decrease in CAT activity in Q. robur axes was seen upon slow dehydration and wet storage. Similarly, the activity of CAT declined as desiccation of axes of T. dregeana proceeded. In contrast, CAT activity inA. marina axes increased during slow drying. Whereas the activity of GR in axes of P. sativum increased during drying and wet storage, GR activity decreased in A. marina axes upon all treatments such that the activity ofGR was higher during rapid than slow dehydration. GR activity also declined upon slow desiccation and hydrated storage ofaxes of Q. robur. Similarly, the activity of GR in T. dregeana axes was reduced during moist storage. Finally, a decrease in the level of AsA in axes of P. sativum took place during drying. Nonetheless, dehydration and wet storage of Q. robur axes were associated with no siginificant change in AsA levels. There was also a decline in the level of AsA in axes of T. dregeana as rapid desiccation proceeded. Similarly, a reduction in AsA level occurred upon slow drying ofaxes ofA. marina. The results presented here are consistent with the observation that drying and wet storage adversely affected the respiratory enzymes, PFK, MDH and NADH dehydrogenase. It is suggested that the resultant metabolic imbalance led to more leakage of electrons from the mitochondrial electron transport chain than normal, and through lipid peroxidation increased levels of hydroperoxides. In addition, dehydration and hydrated storage may depress the activities of free radical processing enzymes, SOD, CAT and GR and levels of antioxidant, AsA. This phenomenon was less pronounced during rapid, in comparison to slow, desiccation and moist storage. However, it appears that the above biochemical events are overtaken by physical damage at higher water contents in the highly recalcitrant seeds. It was concluded that the differential effects of VII the drying rate and wet storage on responses of desiccation-sensitive seeds varies with tissue, harvest, species and the degree of desiccation sensitivity. / Thesis (Ph.D.)-University of KwaZulu-Natal, 2004.
9

The development of clone-unspecific micropropagation protocols for three commercially important Eucalyptus hybrids.

Chetty, Senica. January 2001 (has links)
Micropropagation methods are often used to supplement existing clonal programmes for Eucalyptus species. However, genotypic differences among clones require the implementation of clone-specific protocols, an expensive and labour-intensive exercise. Hence, this study aimed at determining high-yielding hybrid-specific rather than clone-specific, micropropagation protocols for E. grandis x nitens (GN), E. grandis x nitens (NH), and E. grandis x urophylla (GU). Different conditions for surface sterilisation, bud-break (3 protocols, 2 media), multiplication (4 media), elongation (2 protocols) and rooting (4 media) were tested. A single successful surface sterilisation approach was possible for all clones of the tested hybrids (0.0-11.8% contamination, 0.0-22.9% necrosis). It involved rinsing nodal explants in a fungicide mixture (lg/l Benlate, 1g/1 boric acid, 0.5ml/1 Bravo, Tween 20) for 15 minutes followed by calcium hypochlorite (10g/l with Tween 20) for three minutes. Results at each culture stage were dependent on genotypes, and results indicated here represent ranges in values among the clones of each hybrid. The highest bud-break values for GN clones (87-90%) and NH clones (17-75%) were achieved on a medium containing MS, 0.1mg/1 biotin, 0.1mg/l calcium pantothenate, 0.04mg/1 NAA, 0.11mg/l BAP and 0.05mg/1 kinetin. In GU clones, bud-break values on this medium (84-97%) were not significantly different to those achieved directly on a multiplication medium (80-91%) (MS, 0.1 mg/l biotin, 0.1 mg/l calcium pantothenate, 0.2mg/l BAP, 0.01mg/1 NAA). Shoot multiplication yields for GN clones (4-13 shoots/bud) and GU clones (2-6 shoots/bud) were achieved on a medium consisting of MS, 0.1mg/1 biotin, 0.1 mg/l calcium pantothenate, 0.2mg/1 BAP and 0.01 mg/l NAA. As genotypic effects were highly significant among NH clones, a single multiplication medium for all clones of this hybrid could not be determined. The best method of elongation for clones of all three hybrids involved culturing shoots on MS, 0.1 mg/l calcium pantothenate, 0.1mg/1 biotin, 0.35mg/1 NAA, 0.1mg/l kinetin and 0.1mg/1 IBA, under photoperiod conditions, rather than total darkness, for 6 weeks. This resulted in 82.3-86.6% elongation and shoot lengths increasing by 22.9-35.2 mm for GN clones, 80.2-82.3 % elongation and an increase in length of 24.7-32.2 mm for NH clones and 70.8-78.1 % elongation, and shoot elongation of 21.6-29.3 mm for GU clones from passage 1-2. For all the above stages, media contained 20/25 g/l sucrose and 3.5g/l Gelrite, and cultures were maintained at 25°C ± 2°C day/ 21°C night with a 16 h light/ 8 h dark photoperiod (PPFD 66µmol/m2/s). In terms of rooting, cultures on different media were initially subjected to a 72 hour period of total darkness at room temperature, then a 16 h light/8 h dark photoperiod (PPFD 37µmol/m2 /s) at 24°C day/ 21°C night for 7 days. This was followed by a 16 h light/ 8 h dark photoperiod (PPFD 66µmol/m2/s) at 25°C ± 2°C day/ 21°C night for 21 days. Tested clones of the three hybrids were all rooted successfully (56-93% rooting in GN clones, 36-76% rooting in NH clones and 46-96% rooting in GU clones) on a medium containing ¼ MS, 0.1 mg/l biotin, 0.1 mg/l calcium pantothenate, 0.1mg/l IBA, 0.22g/1 CaCI2 .2H20, 0.185g/l MgS04.7H2O, 15g/l sucrose and 3.5g/1 Gelrite. Predicted yields from the established protocol are also presented (168-667 plants of E. grandis x nitens (GN), 35- 854 plants of E. grandis x nitens (NH) and 54-349 plants of E. grandis x urophylla from 100 initial nodal explants, depending on the clone). Hence, the established protocols can be used successfully for some of the clones, but the implementation of specific media and methods to obtain high yields may still be necessary for certain clones. / Thesis (M.Sc.)-University of Natal, Durban, 2001.
10

The spatial ecology of lion (Panthera leo) and spotted hyaena (Crocuta crocuta) in Hluhluwe-iMfolozi Park : implications for the African wild dog (Lycaon pictus.

Graf, Jan Andreas. January 2008 (has links)
The ecological role of apex predators in ecosystems is increasingly recognized not only as a result of their affects on prey species, but also on the numbers and behaviour of other predator species within their guilds. In an African context, dominant apex predators such as lions (Panthera leo) and spotted hyaenas (Crocuta crocuta) have been implicated in limiting endangered intraguild species such as wild dogs (Lycaon pictus) via direct intraguild interactions, such as interference and predation. As a result of this it has been predicted that spatial and temporal refugia are critical for wild dogs to co-exist with lions and spotted hyaenas. Whether such refugia are actually present within small protected areas, such as Hluhluwe iMfolozi Park (HiP), within which these three species co-exist, has been questioned. For wild dogs, interference or predation refugia may be equated to areas or periods which contain a relatively low level of encounter probability with spotted hyaenas and lions respectively. By combining well established field research techniques, such as radio telemetry and audio playbacks, with novel geographic information system tools, I investigated the two key drivers of the probability of encounter with spotted hyaenas and lions, namely density and utilization intensity. Results from the analyses showed that substantial spatial and temporal variation existed in the utilization intensity of lions, as well as the density of both lions and spotted hyaenas, at short and intermediate time scales, in HiP. The spatial scale across which these patterns resolved appear to be well suited to the movement capabilities of wild dogs. This indicated that wild dogs may be able to exploit such areas of temporary lower density and/or utilization intensity, suggesting the dynamic nature of refugia involved in the interactions within these two species-pairs. Results from the lion analyses further suggest that groups rather than individuals are the basic units around which intraguild interactions of social predator and prey species should be investigated, and that social grouping in combination with predator territoriality may stabilize intraguild interactions. An important prediction emerging from this work is that wild dogs, or other subordinate African large predator species, may be forced to trade-off safety from hyaena interference vs. safety from lion predation. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009. / National Research Foundation, The Green Trust (WWF–SA), The Wildlands Conservation Trust, University of KwaZulu-Natal, The Endangered Wildlife Trust, Smithsonian Institution, Sichel Family Endowment, Friends of the National Zoo, THRIP, Wild about Cats, Hluhluwe Tourism Association, Bateleurs, Third World Academy of Science, The Wild Dog Foundation, and The Sally Club.

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