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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.
11

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
12

Taksonomie, taksidermie en diorama : bewaring in die poësie van Johann Lodewyk Marais

Maree, Linda 01 1900 (has links)
Text in Afrikaans / In hierdie navorsingsverslag word die omgewingsgerigte poësie van Johann Lodewyk Marais ondersoek. Marais se verskuns word onder meer as “groen”, “omgewingsgerig”, “ekopoëties”, “bioregionaal” en “biogeografies” beskryf en kritici is dit eens dat sy oeuvre ‘n sterk bewaringsingesteldheid vertoon. Marais se eiesoortige bydrae tot die bewaringsdiskoers (deur sowel sy verse as kritiese uitsprake) word hier geëvalueer aan die hand van sekere sleutelkonsepte uit die museum- en bewaringswetenskap wat telkens as metafore in sy poësie figureer: taksonomie, taksidermie en diorama. Saamgelees met Halloran se idee van die teks as argivale ruimte of museum, word hierdie konsepte (naamlik taksonomie, taksidermie en diorama) voorgehou as ‘n leesstrategie waarmee die bewaringsgesinde poësie van Marais gedekodeer kan word. / This research report focuses on the environmental poetry of Johann Lodewyk Marais. His poetry has been described as “green”, “environmental”, “ecopoetical”, “bioregional” and “biogeographical” and critics agree that the oeuvre displays a strong element of conservation and even preservation. Marais’s unique contribution towards this discourse of conservation is assessed by utilising certain key concepts from museology, which frequently manifests in his poetry as metaphors: taxonomy, taxidermy and diorama. Halloran’s notion of the text as archival space or museum, read in tandem with these concepts of taxonomy, taxidermy and diorama, is then presented as a reading strategy for decoding Marais’s poetry. / Afrikaans & Theory of Literature / M.A. (Afrikaans)
13

Taksonomie, taksidermie en diorama : bewaring in die poësie van Johann Lodewyk Marais

Maree, Linda 01 1900 (has links)
Text in Afrikaans / In hierdie navorsingsverslag word die omgewingsgerigte poësie van Johann Lodewyk Marais ondersoek. Marais se verskuns word onder meer as “groen”, “omgewingsgerig”, “ekopoëties”, “bioregionaal” en “biogeografies” beskryf en kritici is dit eens dat sy oeuvre ‘n sterk bewaringsingesteldheid vertoon. Marais se eiesoortige bydrae tot die bewaringsdiskoers (deur sowel sy verse as kritiese uitsprake) word hier geëvalueer aan die hand van sekere sleutelkonsepte uit die museum- en bewaringswetenskap wat telkens as metafore in sy poësie figureer: taksonomie, taksidermie en diorama. Saamgelees met Halloran se idee van die teks as argivale ruimte of museum, word hierdie konsepte (naamlik taksonomie, taksidermie en diorama) voorgehou as ‘n leesstrategie waarmee die bewaringsgesinde poësie van Marais gedekodeer kan word. / This research report focuses on the environmental poetry of Johann Lodewyk Marais. His poetry has been described as “green”, “environmental”, “ecopoetical”, “bioregional” and “biogeographical” and critics agree that the oeuvre displays a strong element of conservation and even preservation. Marais’s unique contribution towards this discourse of conservation is assessed by utilising certain key concepts from museology, which frequently manifests in his poetry as metaphors: taxonomy, taxidermy and diorama. Halloran’s notion of the text as archival space or museum, read in tandem with these concepts of taxonomy, taxidermy and diorama, is then presented as a reading strategy for decoding Marais’s poetry. / Afrikaans and Theory of Literature / M.A. (Afrikaans)

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