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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.
61

Local and regional factors influencing dung beetle assemblage structure across an environmental gradient in Botswana

Tshikae, Balatlhane Power 19 October 2011 (has links)
The taxonomic composition, structure, and diversity of current local species assemblages results from an interacting complex of historical, regional ecological and local ecological factors. Structural differences between such current species assemblages are primarily determined by changing ecological conditions across spatial gradients. These conditions may change abruptly or they may represent a gradual divergence. Across the Botswana Kalahari basin there is a gradual northeast-southwest aridity and dung type gradient, which was demonstrated to strongly influence dung beetle assemblage structure at six study sites from Chobe National Park to the Central Kalahari Reserve to the Kgalagadi Transfrontier Park using carrion and four dung types as bait (pig, elephant, cattle, sheep). Regional patterns were primarily influenced by climate (rainfall) while dung type mainly showed a local influence on patterns of variation. Four distinct biogeographical groups were defined for the study region comprising widespread, northeast/widespread, northeast, and arid southwest Kalahari-centred species. Biogeographical diversity was higher in the more mesic NE than the arid SW but varied somewhat between bait types. In the SW, Kalahari endemics dominated all bait types. In general, abundance and species richness declined along the aridity gradient although the pattern was uneven due to low numbers in the north of the Central Kalahari Game Reserve. Species showed high turnover (beta – diversity), particularly between the moister NE and the Kalahari/Savanna ecotone. Hierarchical Analysis of Oblique Factors showed statistically distinct separation between assemblage structure at the six study sites and that the proportion of mesic NE shared influence on assemblage composition declined towards the SW where there was an increase in Kalahari endemics. Similarly the proportion of arid SW shared influence declined towards the NE. Plotting these results onto a map showed that the point of intersection between shared NE or SW influence lay very close to the ecotone between SW (Kalahari Xeric Savanna) and NE-centred ecoregions (Acacia-Baikiaea Savanna) defined for the area by Olson et al. (2001). In terms of dung type diversity, increasing aridity across the Kalahari represents a gradient of diminishing resources with the loss of large dung types to the SW and increasing dominance of dung pellets. Several different patterns of response were shown using different methods. Four principal patterns of bait type association were indicated by one method. Another method showed that, rather than diminishing numbers of competing species leading to widening niche widths to the SW, niche widths were narrowest at the Kalahari / mesic Savanna ecotone. Using several other multivariate techniques, three different patterns of dung type resource partitioning were demonstrated that paralleled the aridity gradient, one common to the NE and two to the SW. The historical, regional and local ecological factors influencing these patterns of dung beetle assemblage structure are discussed as well as implications and recommendations for conservation. / Thesis (PhD)--University of Pretoria, 2011. / Zoology and Entomology / unrestricted
62

Isolation, propagation and rapid molecular detection of the Kalahari truffle, a mycorrhizal fungus occurring in South Africa

Adeleke, Rasheed Adegbola 03 April 2013 (has links)
Terfezia pfeilii is an edible mycorrhizal fungus that thrives in the Kalahari Desert of southern Africa. It is best known by desert dwellers for its flavour and as a source of nutrition. Although the genus Terfezia is generally regarded as being an ectomycorrhizal mycobiont, the exact mycorrhizal type formed by T. pfeilli and its' associated host plants remains uncertain. Discovery of the host plants for T. pfeilii would first be required in order to further investigate the life cycle and cultivation of this truffle. This study focussed on the isolation of mycelia from the ascocarp, optimising the growth conditions of the mycelial cultures, rapid molecular identification of T. pfeilii, investigation of potential helper bacteria and mycorrhizal synthesis experiments. T. pfeilii ascocarps were harvested from the Spitskop Nature Reserve in Upington, South Africa. Ascocarps were successfully identified using both morphological and molecular methods. Despite the delayed growth mostly caused by contaminating microorganisms, the isolation of T. pfeilii mycelia culture was successful. Molecular techniques were used to confirm the identity of the pure culture. Further studies were conducted on ways to improve the growth conditions of the mycelial culture on Fontana medium. An optimum temperature of 32°C, the addition of Bovine Serum Albumin as a nitrogen source and a pH of 7.5 significantly improved the growth of T. pfeilii in vitro. A rapid PeR-based molecular method was developed to speed up the identification of T. pfeilii. Specific primers that can exclusively amplify the ITS region of T. pfeilii were designed and used to identify both the ascocarps and the mycelial culture. The specificity of these primers was confirmed by their inability to amplify DNA from the isolates of contamining fungi obtained during the isolation process. Molecular comparison was made to confirm the reclassification of South African samples of T. pfeilii as Kalaharituber pfeilii as proposed by Ferdman et al.,(2005). However, in this study, the name T. pfeilii has been retained. A total of 17 bacterial isolates were obtained from the fruiting bodies of T. pfeaii and these were tested for stimulation of mycelial growth in vitro, indole production and phosphate solubilising capabilities. Bacterial isolates that showed potential to be Mycorrhization Helper Bacteria (MHB) were identified as Paenibacillus sp., Bacillus sp. and Rhizobium tropici. Selected plant seedlings were inoculated with T. pfeilii cultures or ascocarp slurry in order to re-establish the mycorrhizal association. After 8 months, light microscopy observations revealed an endomycorrhizal type association between Cynodon dactylon and T. pfeilii. This was confirmed with molecular analysis using specific T. pfeilii ITS primers. After 15 months, molecular methods confirmed Acacia erioloba as another host plant. These results have provided essential information paving the way for further investigation into the life cycle and biology of the Kalahari truffle. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in
63

Understanding plant resource use by the ≠Khomani Bushmen of the southern Kalahari

Mannetti, Lelani 03 1900 (has links)
Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Previously, conservation activities were mainly focussed upon the establishment of protected areas that safeguarded and shielded the natural world from misuse, often resulting in the forced removal of indigenous communities. In South Africa, the ≠Khomani Bushmen, were one such group forcibly evicted from their homelands. Today, the community has regained access to their ancestral lands in the form of a land claim, settled in 1999, that awarded the community land rights in the form of six farms and land use rights within the now Kgalagadi Transfrontier Park (KTP). This gave them the right to use and manage their property falling within the park together with the conservation authority responsible for the Park, South African National Parks (SANParks). This study aims to improve our understanding of the use of resources by the ≠Khomani Bushmen. By obtaining insight on resource use and how knowledge of this use is transferred and shared, information on how to better involve and integrate the community in management processes is generated. The study identified the most important plants currently used within the ≠Khomani community and assessed this use. Additionally, social network analysis (SNA) was used to investigate how the social network structure depicts the distribution of knowledge which affects the community’s ability to manage their natural plant resources effectively. In an ethnobotanical survey, over 90 individuals were interviewed, using semi-structured interviews, on the farms awarded to the community. In total, 59 plant species from 28 families were found to be in use. Medicinal plants were most frequently cited (60%), with edible plants comprising a further 20%. Data was also collected on social relations surrounding the acquisition, generation and transfer of plant use knowledge. The knowledge networks all depict isolated individuals on the periphery and a few individuals loosely connected to central structures. This study demonstrates that wild plant use remains an important practice for the ≠Khomani people, primarily for medicinal purposes. It serves as baseline data on plant resources being used by the community and adds to our understanding of how traditional knowledge is being transmitted. The insight provided by SNA depicts the current distribution of knowledge and should be used by the community, as supported by network weavers and SANParks, to achieve their joint management goals. Network weaving can potentially counteract ecologically unsustainable practices, promoting collaboration and the transfer of traditional ecological knowledge. / AFRIKAANSE OPSOMMING: Voorheen was bewaringsaktiwiteite meestal gefokus op die vestiging van beskermde areas wat die natuurlike wêreld beveilig en beskerm het van misbruik wat dikwels die gevolg was van die geforseerde verwydering van inheemse gemeenskappe. In Suid-Afrika was die ≠Khomani Boesman groep een van die sodanige groepe wat op ʼn indrukwekkende manier van hulle tuislande uitgesit is. Vandag het die gemeenskap weer toegang gekry tot die land van hulle voorvaders in die indiening van ʼn grond eis wat in 1999 vasgestel is, en wat die gemeenskap grond regte toegeken het in die vorm van ses plase en grond regtelike gebruik binne die sogenoemde Kgalagadi Transfrontier Park (KTP). Dit het hulle die reg gegee tot die gebruik en bestuur van hulle eiendom wat binne die park val saam met die bewaringsowerhede wat verantwoordelik is vir die Park, Suid-Afrikaanse Nasionale Parke (SANParks). Die doel van hierdie studie is om ons begrip te verbeter van die gebruik van hulpbronne deur die ≠Khomani Boesman. Met die verkryging van insig oor hulpbron gebruik en hoe die kennis van hierdie gebruik oorgedra en gedeel word, is inligting oor hoe om ʼn beter betrekking en integrering van die gemeenskap in die bestuursprosesse gegenereer. Die studie het die belangrikste plante geïdentifiseer wat tans gebruik word binne die ≠Khomani gemeenskap met die doel om die gebruik van hierdie plante te assesseer. Sosiale netwerkanalise (SNA) is addisioneel gebruik om ondersoek in te stel oor hoe sosiale netwerk struktuur die verspreiding van kennis uitbeeld wat die gemeenskap se vermoë om hulle natuurlike plant hulpbronne effektief te bestuur affekteer. In ʼn etnobotaniese opname, was oor 90 individuele ondervra op die plase wat aan die gemeenskap toegeken was, met die gebruik van semi-gestruktureerde onderhoude. Dit is gevind dat in totaal 59 plant spesies uit 28 families gebruik word. Medisinale plante was meer dikwels aangehaal (60%) met eetbare plante bestaande uit 20%. Data was ook versamel oor sosiale verwantskappe omringende die verkryging, generering en oordra van kennis in die gebruik van plante. Hierdie netwerk van kennis word alles uitgebeeld in geïsoleerde individue op die periferie en ʼn paar individue wat losweg verbonde is tot sentrale strukture. Hierdie studie identifiseer dat die gebruik van wildeplante ʼn belangrike praktyk bly vir die ≠Khomani mense, hoofsaaklik vir medisinale doeleindes. Dit dien as basis inligting van plant hulpbronne wat tans gebruik word deur die gemeenskap en wat by ons begrip gevoeg word oor hoe tradisionele kennis oorgedra word. Die insig wat deur SNA voorsien word beeld die huidige verspreiding van kennis uit, wat deur die gemeenskap gebruik moet word, as ondersteuning van “network weavers” en SANParks om hulle gesamentlike bestuur doelwitte te bereik. “Network weavers” kan potensieel ekologiese onvolhoubare praktyke teenwerk, wat die samewerking en die oordra van tradisionele ekologiese kennis bevorder.

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