Anthrax was associated with the death of a large number of animals in the Selous Game Reserve. The significance of this disease to the populations of these animals was of concern to the reserve's management. Models are presented of the evolutionary effects of four host-pathogen relationships. Based on a demographic study of the wildebeest and a study of the characteristics of the disease, the anthrax-wildebeest relationship was compared with the models. The results of the study indicate that even though anthrax was responsible for the death of approximately 10% of the wildebeest, it had a balanced relationship with the population. The pathogen was probably an asset to its host population's continued existence rather than a hazard, as its mortality was associated with animals that appeared to be a disadvantage to the wildebeest population. If the management of the reserve wished to reduce the occurrence of anthrax, it is suggested that they reduce the number of wildebeest older than calves. In addition to maintaining a stable age configuration, this would improve the quality of the habitat, reduce the number of animals in poor condition, and thus reduce the number dying of anthrax. In addition, I deal with several other topics in Appendices. / Science, Faculty of / Zoology, Department of / Graduate

Dissertation (DPhil)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis (PhD (Archaeology))--University of Stellenbosch, 2005. / This study investigates the evolution of modern mammalian faunas in the central interior of southern Africa by testing the hypothesis that the evolution of the black wildebeest, Connochaetes gnou, was directly associated with the emergence of Highveld-type open grasslands in the central interior. Southern Africa can be distinguished from other arid and semi-arid parts of the continent by the presence of an alliance of endemic grazing ungulates. The black wildebeest is characteristic of this alliance. Open habitats are essential for the reproductive behaviour of the black wildebeest, because territorial males require an unobstructed view of their territories in order to breed. The specialised territorial breeding behaviour of the black wildebeest is the reason why the black wildebeest is historically confined to the Highveld and Karoo areas and why it is reproductively isolated from sympatric blue wildebeest, Connochaetes taurinus. The finds from a number of fossil-rich localities, dating from the recent past to approximately a million years ago, have been identified. The remains referred to ancestral C. gnou have been subjected to detailed qualitative and quantitative osteological comparisons with cranial and post-cranial elements of modern and fossil reference specimens. This material includes extant southern African alcelaphines and fossil materials of C. gnou, the extinct giant wildebeest, Megalotragus priscus, and North African fossil alcelaphines. The results show that cranial changes in fossil C. gnou, particularly the more forward positioning of the horns, basal inflation of the horns and the resultant re-organisation of the posterior part of the skull, preceded other skeletal modifications. These cranial changes indicate a shift towards more specialised territorial breeding behaviour in the earliest ancestral black wildebeest, evident in the specimens of the c. million year old Free State site of Cornelia-Uitzoek. Since the territorial breeding behaviour of the black wildebeest can only function in open habitat and since cranial characters associated with its territorial breeding behaviour preceded other morphological changes, it is deduced that there was a close association between the speciation of C. gnou from a C. taurinus-like ancestor and the appearance of permanently open Highveld-type grasslands in the central interior of southern Africa. This deduction is supported by the lack of trophic distinction between the modern black and blue wildebeest, suggesting that the evolution of the black wildebeest was not accompanied by an ecological shift. It is concluded that the evolution of a distinct southern endemic wildebeest in the Pleistocene was associated with, and possibly driven by, a shift towards a more specialised kind of territorial breeding behaviour, which can only funtion in open habitat. There are significant post-speciation changes in body size and limb proportions of fossil C. gnou through time. The tempo of change has not been constant and populations in the central interior underwent marked reduction in body size in the last 5000 years. Vicariance in fossil C. gnou is evident in different rates of change that are recorded in the populations of generally smaller body size that became isolated in the Cape Ecozone. These daughter populations, the result of dispersals from the central interior, became extinct at the end of the Pleistocene.