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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

Patterns of animal endemism in the Maputaland-Pondoland-Albany biodiversity hotspot.

Perera, Merennage Sandun Jayalal. 12 September 2014 (has links)
The Maputaland-Pondoland-Albany (MPA) hotspot, as is the case of all such global biodiversity hotspots, has primarily been recognised based on its high floristic endemism and delimited intuitively. Boundaries of global biodiversity hotspots have seldom been empirically tested in terms of species distribution patterns and only a few have been examined for patterns of animal endemism. This thesis presents the results of a zoogeographical study of all five major vertebrate groups and selected invertebrate groups in south-eastern Africa, refining the delimitation of the MPA hotspot and identifying areas and centres of endemism within and around it. It also provides zoogeographical regionalisation schemata for the whole of south-eastern Africa. The study employed methods of, (a) preliminary qualitative identification of “Endemic Vertebrate Distributions”, (b) phenetic clustering of operational geographical units based on species incidence matrices, using the Jaccard’s coefficient of similarity and the Unweighted Pair-Group Method using Arithmetic means (UPGMA) clustering algorithm, (c) Parsimony Analysis of Endemicity, and (d) ArcGIS-based mapping of various measures of endemism (e.g. narrow endemism and weighted endemism). The results reveal that the MPA hotspot, though defined so due to its exceptional floristic endemism, is a hotspot for the endemism of animals too, especially for the herpetofauna and invertebrate groups like the velvet worms, land snails and many others. But the current boundary of the hotspot is arbitrarily defined and not exactly matching the patterns of animal endemism (and, likely, neither those in plants). Hence, a greater Maputaland-Pondoland-Albany (GMPA) region of animal endemism is proposed as a broad priority region of conservation concern, while centres of endemism within the GMPA are identified and patterns of quantitative measures of endemism are mapped. The study also proposes a zoogeographical regionalisation placing the GMPA and Highveld regions at the province rank in the global zoogeographical hierarchy, within the south east African dominion, also describing zoogeographical districts and assemblages nested within each. Results from the vertebrate and invertebrate analyses reveals the possibility of a common zoogeographical regionalisation for south-eastern Africa. The study emphasises the importance of quantitative biogeographical methodologies in conservation biogeography, in addition to their uses in the theoretical/descriptive biogeography. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2013.
2

Historical biogeography of the tribe Platypleurini Schmidt, 1918 (Hemiptera: Cicadidae) with a focus on Southern Africa

Price, Benjamin Wills January 2010 (has links)
With our contemporary biota under increasing threat of extinction, it is of interest to understand where, why and how biological diversity is generated. If focussed on appropriate taxa, phylogeographic and phylogenetic studies can assist in the identification of both places and processes central to the origin and maintenance of biological diversity. It is explained why southern Africa presents a perfect test-bed for exploring such mechanisms of diversification and why cicadas (Hemiptera: Cicadidae) have proved very suitable tools for studies of historical biogeography. This study then exemplifies these points by providing the first large-scale investigation of the historical biogeography of the tribe Platypleurini Schmidt, 1918, with emphasis on the genus Platypleura Amyot & Seville, 1843 in southern Africa. Standard methods of DNA sequencing provided data from portions of the mitochondrial small subunit ribosomal 16S RNA (16S) and cytochrome oxidase subunits I (COI) and II (COII); and the nuclear elongation factor 1 alpha (EF-1α) from 400 ethanol-preserved specimens. These data were analysed using standard phylogenetic methods and a time scale of diversification was estimated using a Bayesian framework and both fossil data and DNA substitution rates. The results showed that the tribe is too recent to be of Gondwanan origin. The lack of monophyly of the genera represented in both Asia and Africa showed that the tribe needs formal taxonomic revision. Diversification of the African platypleurine genera coincides with aridification in the early Oligocene. Dispersal of Asian platypleurine taxa coincides with the meeting of Africa and Eurasia in the mid-Oligocene. Two radiations within African Platypleura are hypothesised; one distributed over most of sub-Saharan Africa and the second restricted to southern Africa, with clades restricted within regional biomes. Within each of the three focal biomes, cryptic taxonomic diversity was confirmed, suggesting that, even in relatively well understood groups such as the southern African platypleurine cicadas, molecular data can identify further diversity. Although each focal taxon was restricted to non-overlapping biomes, comparison of the three biomes highlighted interactions between palaeoclimates and fixed landscape features (coastal topography, river catchments and escarpments) as causative agents of vicariance, dispersal, extinction and diversification of these volant insects. The results of using co-distributed species for comparative study cautions against making inferences based on single-taxon datasets and highlights the need to use many, evolutionarily independent taxa when identifying mechanisms of diversification. The dating analyses imply that within-species lineage diversification occurred overwhelmingly within the Pleistocene, a trend that is being increasingly recognised in print for other biota. Some caveats about using phylogenetic approaches to estimate ancestral areas are illustrated. Several recommendations are made regarding additional taxa and data sources for understanding the origin and maintenance of biological diversity.

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