The house sparrow, Passer domesticus, is one of the most successful invading bird species in the world. It was introduced to southern Africa around 1900 and has since spread through the region. Its dispersal was characterised by an initial slow phase followed by a rapid increase in the rate of spread. Following 50 years of slow spread, the rate of dispersal accelerated to over 80 km/year. The initial slow rate can be attributed to an Allee effect, defined as "a disproportionate reduction in reproduction below a threshold population density due to reduced probability of finding a mate". The rapid phase involved a combination of long-range jumps (leap-frogging dispersal) and diffusive movement over short distances. Dispersal was significantly faster along railway lines. Introduction of the house sparrow, Passer domesticus, to southern Africa involved unknown numbers of both the domesticus race of Europe and indicus of Asia, resulting in the establishment of a genetically diverse founder population along coastal South Africa. The birds have undergone significant differentiation since introduction about 100 years ago. Significant sexual size dimorphism was detected among southern African house sparrows, especially in flight structures. Males were larger than females in all characters except tarsus and claw length. Overall body size variation was clinaly ordered with a general increase in size with latitude in conformity with Bergmann's rule. Tarsus length also increased southwards, with the longest tarsi in birds of coastal sites in South Africa and the shortest in Zimbabwe. Patterns of variation in morphological characters paralleled climatic trends, especially minimum temperature and humidity. Beak size and shape of Zimbabwean birds appeared to be under the greatest influence of climatic factors. Shorter and more conicaly shaped beaks were selected for in females in Zimbabwe. Natural selection was modifying the morphological characters resulting in adaptive radiation in morphology of southern African populations. Few studies of microevolution (change in morphology over a short period) have been conducted in birds and none in invading bird species in the tropics. A founding population comprising both the Asian and the European races of the house sparrow, P. d. domesticus and P. d. indicus first arrived in Zimbabwe 30 years ago. Because of its recent introduction to Zimbabwe and because of its known potential for rapid adaptation and differentiation elsewhere in its new range, the house sparrow provided the ideal case study in microevolution in tropical Africa. Morphological differentiation in Zimbabwean populations of the house sparrow was analysed to determine temporal variation in local samples and the extent of variation from parent populations of Asia and Europe. Samples collected since arrival in Zimbabwe up to 1980 were compared with those collected from current populations in 1998/1999 to determine local changes over time. The Zimbabwean samples were then contrasted with samples from Asian and European populations to determine the extent of differentiation in the introduced birds of Zimbabwe. Zimbabwean populations had differentiated from their Asian parents in six of the seven morphological characters examined. The greatest differentiation was in beak size and shape for both males and females. Males developed larger beaks and shorter wings than the Asian birds and female beaks became more conical. A large proportion of the potential phenetic diversity of the founding population of both domesticus and indicus genes had been realised in Zimbabwe. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

No abstract available. / Thesis (Ph.D.)-University of Natal, Durban, 1977.

No abstract available. / Thesis (Ph.D.)-University of Natal, Durban, 2001.

Chaerephon pumilus, the little free-tailed bat, (family: Molossidae) has a distribution throughout most of sub-Saharan Africa and the eastern region of Madagascar. The vast geographical distribution of this species is accompanied by considerable phenotypic variation, which may conceal cryptic species. The cytochrome b (845 nucleotides) and D-loop (314 nucleotides) regions of the mitochondrial DNA were sequenced to assess phylogenetic relationships within C. pumilus (southern Africa) and in relation to Chaerephon species from Madagascar (C. pumilus, C. leucogaster). Samples were obtained from KwaZulu-Natal, South Africa, and localities in Swaziland. The cytochrome b sample (n = 11) comprised four haplotypes, with a haplotype diversity of 0.6727, whilst the D-loop (n = 34) dataset comprised 13 haplotypes with a haplotype diversity of 0.8342. Neighbour joining, maximum parsimony and Bayesian analyses revealed congruent tree structures for both mtDNA regions. All Chaerephon taxa in this study formed a monophyletic clade with respect to the outgroup Mops midas. Chaerephon pumilus from the eastern side of Madagascar formed a well-supported monophyletic group, sister to a clade comprising C. pumilus (southern Africa) and C. leucogaster, and is suggested to comprise a separate species. Southern African C. pumilus formed two paraphyletic clades, A and B, separated by a genetic distance of 0.9 %. Chaerephon leucogaster formed a monophyletic group nested within southern African C. pumilus, suggesting conspecificity. However, the well-characterized morphology of C. leucogaster lends support to its specific status, and suggests the possible existence of cryptic species among southern African C. pumilus. Population genetic analysis suggests that two C. pumilus (southern African) clades have been expanding, one for between 2432 and 4639 years, and the other for the 11156 to 21280 years. A combined cytochrome b analysis, trimmed to 343 nucleotides, was carried out on the data from this study and that of Jacobs et al. (2004), also on southern African C. pumilus. Haplotypes from the Jacobs et al. (2004) study, which also identified two 0.9 % divergent clades (light- and dark-winged) were found to be identical or very similar to haplotypes from this study and were interspersed among southern African C. pumilus haplotypes in phylogenetic analyses. Chaerephon pumilus haplotypes from Zambia and Tanzania were found to be more closely related to those from southern Africa and to C. leucogaster than to C. pumilus (Madagascar), further indicating that this may be a separate species. Haplotypes from the light-winged clade of Jacobs et al. (2004) were identical to those of dark-winged samples from this study, suggesting that wing shade may not be diagnostic of the two clades. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.

The use of fibre reinforced polymer composites and development of structural composites has expanded rapidly in the Southern African region over the past ten years. The long-term effect of placing these materials outdoors in the Southern African climate is unknown with exposure data for these materials being primarily European and North American based. This study intends to take a broad-based study to the problem of environmental degradation of advanced composite structures. This work is intended to study different degradation mechanisms. Work performed includes: a study of literature on degradation and protective measures; identification of dominant degradation mechanisms; manufacture of specimens; accelerated environmental testing; and an assessment of the effect of the exposure on the chemical properties The goal of this work is to produce information, which can be subsequently used to determine the rate of damage, methods of suitable protection and necessary maintenance intervals for polymer composite components. The approach was: to simulate outdoor exposure within a reduced period of time; to establish correlation of results with actual outdoor exposure; and to determine how the gel coats compare with other protective methods. As part of the objectives of the study (i.e. to assess the durability of polymer matrix composites materials subjected to environmental exposure), an experimental study was carried out to establish the durability of specific gel coats against ultraviolet (DV) and moisture degradation. An investigation of the effectiveness of the various protective measures has begun with a review of selected gel coats available as a protective coating. Laminates with these gel coats have been set up for both accelerated and natural exposure tests. 3000, 2500, 2000, 1600, and 800 hours of accelerated DV exposure tests were performed on polyester GRP laminates with gel coats. No measurable strength loss occurred on protected laminates; there was significant increase in yellowness on un-protected laminates; all protected specimens showed a fair retention of gloss; fibre prominence occurred on unprotected laminates; and the glass transition of samples had dropped from the normal polyester glass transition temperature range. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2004.

Theoretical work indicates that HIV-1 epidemics in sub-Saharan Africa will cause major demographic changes. The current study assesses the extent to which these changes can already be seen in two rural areas of Manicaland, Zimbabwe and investigates the determinants of the epidemic and its demographic impact. The study utilizes demographic survey methods and qualitative sociological techniques. Data analysis is conducted using statistical packages and is guided by insights generated from mathematical models of the epidemiology and demographic impact of HIV-1 infections. HIV-1 prevalence is high in both areas. Among women, HIV-1 infection is associated with age and marital status. Indirect evidence indicates that religion, education, migration and socio-economic characteristics of husband may also be important determinants. Each of these factors influences the pattern of sexual behaviour. Rates of sexual partner change are heterogeneous for women but appear more homogeneous for men. Mixing patterns are disassortative: men form partnerships with women with high and low rates of partner change. Mortality has undergone a recent upturn, almost certainly associated with HIV-1 infections. Adults aged 20-45 years and men, in particular, are most affected at this (early) stage of the epidemic. Religion is an important local determinant of demographic patterns, whose influence on mortality appears to be changing vua its effect on sexual behaviour and the spread of HIV-1. Orphanhood has increased, but, as yet, there is little change in population structure. Fertility has declined since the late 1970s. It is too early in the AIDS epidemic to see an impact of HIV-1 at the population level. However, some signs of behaviour changes which affect the proximate determinants of fertility were detected. These changes may accelerate the decline in birth rates, especially at younger ages. New demographic projections for Zimbabwe are developed, based on observed trends in HIV- 1 infection and fertility, and underlying behaviour patterns. These indicate substantial further increases in mortality, particularly among women and young children, greatly reduced population growth, relative shortages of young children and older adults, and further increases in orphanhood. Families and communities will require support in facing this slowly unfolding disaster.

Thesis (M.A. (History))--Rhodes University, 2005.

Thesis (D.Phil(International relations))-University of Pretoria, 2005. / Includes bibliographical references.

The transformation of SADCC into the Southern African Development Community (SADC) has paved the way towards closer regional economic integration in southern Africa. The regional grouping no longer only focuses on sectoral cooperation, but is steadily moving towards increased cooperation in trade development and promotion, industrial development and the diversification of national economies, with the aim of increasing regional economic integration. A free trade area ranks second lowest in the steps towards the highest levels of economic integration. Thus, the signing of the SADC Trade Protocol, which serves to pave way for a SADC Free Trade Area, has initiated steps to facilitate and promote the formal economic integration of all countries in the southern African region. It has been noted that at various periods, the region has adopted a variety of approaches to integration. As such, the present study reviews the different approaches to integration, namely the market integration model, the neo-functional integration model, the development integration model and the theory of common markets. Since the essential question with which this thesis is concerned is whether, and to what extent, the benefits expected from SADC and SACU in terms of their aims and objectives have accrued to member states, an insight into the expected benefits arising from the application of each theoretical framework can help to facilitate an evaluation of the benefits which the countries have enjoyed from these two regional groupings. The thesis highlights that throughout the ten years during which the original SADCC was in place, it based its approach to regional integration on the neo-functional and development integration models, although the former tended to be more dominant. With the regional grouping transforming into SADC, the market integration model was adopted, even though the grouping still had features of the aforementioned approaches. The relevance of the three approaches can be seen in: (i) the continued importance of SADC's sectoral projects, particularly in the field of transport and communication: (ii) continued attempts to put in place a suitable regional) industrial development strategy and implement policies to attract foreign investment; and (iii) the signing of the SADCC Trade Protocol to facilitate the implementation of a free trade area. The thesis argues that member states have enjoyed considerable economic benefits from the SADC sectoral projects. However, in some cases, members have lost out on potential benefits as a result of projects failing to be implemented or completed, mainly due to inadequate funding. Further, delays and inefficiencies at some border posts constitute significant non-tariff barriers which could be a hindrance to intra-regional trade. Progress towards diversification of exports has been limited as the region still relies mostly on the export of the traditional agricultural and mineral raw materials. While all countries have made efforts to diversify their industrial bases, attempts at implementing a meaningful regional industrial development strategy have met with limited success. Intra-regional trade has been increasing over the years. Since the SADC Trade Protocol only came into effect in September 2000, the increased levels of trade integration in the region appear to have been a result of the bilateral trade agreements between countries, and the customs union between South Africa and Botswana, Lesotho, Namibia and Swaziland (BLNS), as well as the structural adjustment programmes and the significant growth experienced in some countries. Outstanding intra-regional trade volumes have been experienced within SACU. In trade terms, benefits have varied between member states, with the more powerful countries like South Africa, Zimbabwe and Mauritius experiencing substantial trade surpluses vis-a.-vis their trade, partners. Countries with bilateral preferential trade agreements have also benefited more due to increased access into each other's markets compared to those without or with bilateral trade agreements of an MFN nature. However, it is important to note that, despite the increase in trade integration in the region, southern Africa is still heavily dependent on the rest of the world for its export markets and as its source of imports. The study finds that intra-industry trade (IIT) exists within the region and, in a number of sectors, high IIT indices are recorded;--although some such sectors do not display significant trade - voIumes. The opening of the region through the implementation of the SADC FTA could promote the expansion of IIT .as-the free trade area )'Till create an enlarged regional market. As such, SADC could benefit from dynamic effects such as scale economies in production and marketing, with member states working on having complementary production structures so as to facilitate specialisation. The thesis argues that the potential for intra-regional trade expansion in the SADC FT A also exists bearing in mind trade complementarity between countries as well as revealed comparative advantages in different sectors. One of the benefits which have accrued to the region as a result of facilitating and promoting greater cooperation and deepening the integration process has been an expansion in cross border investment. The study finds that the 1990s witnessed a gradual increase in cross border investment to take advantage of investment opportunities in member states. South Africa has become the primary source of foreign direct investment flows to a number of SADC countries, with mergers and acquisitions being the dominant mode of its foreign direct investment. Cross border investment helps in supplementing low domestic savings, thus providing substantial parts of the shortfall in capital needed to finance economic growth and development. It can thus promote development in the industrial sector, transfer of capital, skills and technology, and development of infrastructure. Many SADC countries are unable to compete effectively due to lack of export supply capacity. The thesis suggests that capitalising on investment by South African firms could enhance local supply capabilities and raise export competitiveness. The study concludes that for market integration to succeed in the SADC region, the neofunctional and development integration approaches need to be actively pursued simultaneously, particularly with respect to infrastructural and industrial development.

Thunderstorms, due to their high frequency of occurrence over southern Africa, and their major contribution to summer rainfall are the primary focus of very short range forecasting and nowcasting efforts in South Africa. With a limited number of surface and upper-air observations and the limited availability of numerical model output most southern African countries are heavily reliant on satellite technology. In developing tools for the first twelve forecast hours the South African Weather Service has to address both the national and regional needs. Thus, the blending of techniques in an optimal manner is essential. This study initially describes how the Global Instability Index product derived from the European Meteosat Second Generation Satellite was adapted for South African circumstances using a different numerical model to provide background information – creating the Regional Instability Indices (RII). The focus of the study is the development of a new convection indicator, called the Combined Instability Index (CII), which calculates the probability of convection from satellite derived instability indices and moisture, as well as height above sea level early in the morning when the sky is relatively cloud free. Early morning CII values were evaluated statistically against the occurrence of lightning over South Africa, where a lightning network is available, as well as against satellite derived precipitation over southern Africa, later in the same day. It is shown that the CII not only performs well, but also outperforms the individual RII when compared to the occurrence of lightning. The CII will be beneficial to operational forecasters to focus their attention on the area which is most favourable for the development of convection later in the day. / Environmental Sciences / Ph. D. (Environmental Sciences)