School of Animal, Plant and Environmental Sciences (ETDs)
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Item Paternity, floral morphology and pollen viability analyses of African Baobab (Adansonia digitata L.) populations in South Africa(University of the Witwatersrand, Johannesburg, 2023) Hall, Timothy; Glennon, K.L.; Goodman-Cron, G.V.; Venter, S.M.; Witkowski, E.T.F.The African baobab (Adansonia digitata L.) is a valuable flagship, cultural and socio-economic species for communities across Africa. Not only is the baobab an important medicinal plant, but products such as seed oils and fruit pulp are sold to supplement rural community income. Baobab trees produce hermaphroditic flowers, but fruit numbers vary between individuals, with some trees producing many fruit (50 –200) every season, termed producers, and other trees producing little to no fruit every season (< 5), poor producers. This difference is not due to environmental conditions such as rainfall, soil conditions or land use type as tree types occur in the same environment, sometimes only meters apart. The aim of this study was to evaluate how floral reproductive traits and the movement of pollinators between A. digitata producer and poor producer trees may affect the paternity of seed sets from producer trees. I measured seven floral traits of producers and poor producers to assess floral differences using one-way ANOVA between the tree types across three populations in the Vhembe region of South Africa. Floral traits included flower diameter, stamen ball diameter, filament length, anther length, stigma surface diameter, style length from stamen ball emergence and peduncle length. Producers had longer styles emerging from the stamen balls and longer peduncles, whereas poor producers had larger stamen balls, longer filaments, and larger anthers. There were no differences in flower diameter and stigma surface diameter between producer and poor producer trees. Similarly, canopy volume, width, and stem diameter revealed no difference between tree types. Additionally, I evaluated differences in pollen viability between producer and poor producer trees using Alexander’s stain. Although both tree types possess viable pollen, poor producers had nearly 50% higher percentage viability compared to producers. There appears to be some level of functional dioecy across baobab individuals as we found that trees either allocate resources predominantly to either male or female floral structures. Assessing the movement of alleles as a measure of pollen movement between trees may aid in our understanding of how this functional dioecy is influencing allele movement within the population. Eleven microsatellite loci were amplified to assess the paternity of 117 offspring from 13 ‘maternal’ fruit-producing trees across three A. digitata subpopulations in Vhembe, South Africa. v The six nearest potentially paternal trees to each maternal tree were genotyped to test whether they were pollen donors. Parentage analyses conducted using POLYGENE revealed that offspring of maternal trees had alleles from multiple genotyped pollen donor trees outside of their six nearest trees with selected paternal trees contributing pollen to multiple maternal trees. Analyses suggested that pollen dispersed an average of 300 m within subpopulations, but also repeatedly dispersed distances over 40 km between subpopulations. The duration of pollen viability was determined through pollen tube germination trials and aids in our understanding of how long pollen remains viable for in the environment. Pollen grains that were 24, 48 and 72 hours old were deposited on receptive stigmas and allowed to germinate overnight. Scanning electron microscopy was used to confirm pollen tube growth for the three ages of pollen; it indicated that the pollen remains viable for at least 72 hours as it successfully germinated on stigmatic surfaces across these three treatments. This indicates that pollen present in the environment, especially on the surface of pollinators (e.g., moths, bats, or beetles) has the potential to pollinate flowers when up to 72 hours old, although pollen that is older than 72 hours may still be viable, which requires further investigation. The degree of functional dioecy in individual baobab trees, proportion of viable pollen, and extensive potential range of pollen dispersal, all contribute to our knowledge of A. digitata fruit production. Understanding baobab fruiting may aid in future conservation and regeneration strategies and would improve agroforestry security of the species.Item Spatiotemporal Dynamics of Afrotemperate Forests in KwaZulu-Natal, South Africa(University of the Witwatersrand, Johannesburg, 2025-06) Nyembezi, Linda; Fisher, JoleneThis study investigated Afrotemperate forests’ extent and composition from 1940 to 2022 in KwaZulu-Natal, South Africa. Thirty patches were examined (10 small patches (~one hectare), 10 medium patches (~ between 1 and 1000 hectares ) and 10 large patches (~1000 hectares)) over three time periods (1940s, 1980s and 2020s). Aerial photographs, with their high spatial resolution and long temporal extent, were used to estimate forest extent, composition (indigenous versus non-indigenous) and the surrounding land cover. Georeferencing and digitising of aerial photographs was done in QGIS. Fire extent and frequency from 1990-2024 was calculated seasonally using the difference in Normalised Burn Ratio (dNBR) on Landsat and Sentinel images in Google Earth Engine and ArcGIS Pro. Generalised Linear Mixed Models (GLMMs) were run to determine the relationship between forest extent, surrounding land cover and fire. The results of this study indicated that changes in forest extent were patch size specific, with smaller and larger patches increasing in extent and medium patches decreasing in extent. Smaller forests’ expansion in extent was due to the invasion of non-indigenous vegetation. The invasion of non-indigenous vegetation was aided by the high fire extent and frequency that the small forests experienced. Medium sized patches had the highest amount of non-indigenous vegetation in their surrounding matrix which can contribute to the reduction of available water and the degradation of indigenous forests. Larger forest patches are able to buffer the effects of changes in fire and land cover patterns which can aid in indigenous forest expansion. The surrounding matrix of the larger forests had the highest amount of abandoned agricultural land which can promote forest expansion and bush encroachment. Fire extent was highest for the smaller forests possibly due to the high amounts of non-indigenous vegetation found within them. Fire frequency was highest in medium forests’ matrices possibly due to the medium forests having the highest levels of non-indigenous vegetation in the surrounding matrix and the lowest reduction in herbaceous vegetation in the surrounding matrix. Statistically fire extent and land cover were found to impact forest extent independently. The results of this study indicate that small and medium sized forests are at a higher risk of degradation in comparison to larger forests. Therefore the results of this study can be used to inform decisions around where to focus prioritisation efforts for forest conservation.Item Exploring the Extent of Youth Participation in Disaster Risk Reduction in Blantyre, Malawi(University of the Witwatersrand, Johannesburg, 2025-06) Mughogho, Ruth Ntombihle; Vogel, ColeenIn recent years, the world has experienced an increase in the frequency and intensity of disasters. Globally, more than a billion people have been affected. Disaster risk has become more prominent in the context of climate change where global temperatures continue to rise due to anthropogenic and other activities. Climate projections indicate intensified and more frequent disasters. Southern Africa is a climate hotspot owing to its dry and warm climate. With climate change, the region is projected to become warmer and drier resulting in unprecedented extreme events such as drought and heavy rainfall. Disasters often follow extreme events due to people’s exposure and vulnerability. Therefore, reducing exposure and vulnerability will lessen the likelihood of disasters. In order to achieve this, knowledge inputs from wider all facets of society is required. Youth, who make up more than half of the world’s population are disproportionately affected by disasters. They also are often sidelined when it comes to participation in Disaster Risk Reduction (DRR) work often being viewed as a vulnerable group and victims needing protection. Recent studies, however, have shown that they present an important demographic dividend that may be leveraged to further the DRR goal through their human and creative capital, employability, and civic involvement. Malawi, a developing country in southern Africa, has a strong legal and policy framework foundation supporting the participation of youth in DRR. Nevertheless, youth participation in disaster risk reduction seems to be a challenge. This study explored the extent of youth participation in DRR in Blantyre, Malawi. Using qualitative methods, twenty youths ages 18 to 35 were engaged in focus group discussions and key informants from informal institutions working in DRR were interviewed. The focus group discussions revealed that youth participation in DRR in Blantyre is decorative; representing non-participation. This means that youth are engaged in DRR activity implementation, they understand the aim of the activities, but they are not usually involved in any planning and decision-making processes. A number of barriers were discovered through this research which have been categorized into five themes; (1) DRR activities are politicized, (2) Non-consultation – adults plan and make decisions for youth without youth, (3) Limited access to information (4) Non-responsiveness – youth ideas are met with no response and (5) Financial benefits – youth are engaged where projects have no financial benefit, but excluded on ones that do. The study also highlights key disaster impacts experienced by youth in Blantyre and the strategies used for youth participation. Finally, the study provides opportunities, as suggested by the youth for enhancing youth participation which include: (1) Train and empower youth, (2) Include youth in local government committees for DRR, (3) Youth’s passion and motivation for action and (4) Platforms for communication, learning and feedback.Item The role of practitioners in facilitating the public participation process: A review of EIA in renewable energy projects(University of the Witwatersrand, Johannesburg, 2025-06) Madiba, Nthabiseng Pebetse; Watson, IngridThe public participation process is a crucial part of Environmental Impact Assessment (EIA) in renewable energy projects. The role of Environmental Assessment Practitioners (EAPs) in ensuring that this process is carried out as mandated by environmental legislation is equally important. Globally there has been a significant increase in renewable energy projects to support the transition to a low carbon economy. The role played by EAPs and the associated challenges they face when conducting public participation in EIA, particularly in renewable energy projects, has recently been the subject of studies across the globe. The aim of this study was to assess the practice of public participation in South African renewable energy projects, and to explore the role of practitioners in facilitating this process. The methodology employed involved reviewing the documentation from four renewable energy projects, this included the environmental impact reports, public participation reports, and background information documents. Legislation, in particular, the National Environmental Management Act (NEMA), EIA regulations, and NEMA public participation guidelines were reviewed and studied. Furthermore, structured interviews were conducted with EAPs to address the study's objectives. Results indicated that the public participation guidelines and EIA regulations provide clear and concise requirements that EAPs should meet when conducting public participation. However, there is a key contention on the parts of the EIA regulation that give discretion to EAPs in some activities of the public participation process. The findings indicate that to a greater extent EAPs meet the requirements of public participation. EAPs also face some challenges that are unique to renewable energy projects such as lack of public knowledge, the dispersed nature of settlements in the location of renewable energy projects, and lack of public interest when it comes to the participation of Interested and Affected Parties (I&APs) in renewable energy projects. Also, the Covid-19 restrictions on public gathering had both negative and positive impacts on the public participation process. However, on the positive side these restrictions encouraged the use of social media apps and other internet platforms. The conclusions indicates that the EIA regulations and public participation guidelines provide clear and concise requirements for public participation which are implementable and has led to EAPs being able to meet most of these requirements when conducting public participation. One of the key points of contention however was the discretion given to EAPs when it comes to certain practices in public participation. An example is the issue relating to language barriers, wherein minority groups were left out, because communication was only being made in Afrikaans and English. It is recommended that concerning the issue of discretion the regulation should be revised to determine the limitation of this discretion, for example when it comes to language barriers, a multilingual clause should be included in the regulation wherein it makes it mandatory for EAPs to make information available in the language of all registered I&APs to accommodate minority groups. It is further recommended that community engagement and education be promoted when it comes to renewable energy projects to minimise the disinterest of the community in participating due to misconceptions and lack of information. A change in practice is suggested to accommodate all those participating in meetings. As such translation and interpretation services should be offered to ensure meaningful discourse and contribution to decision making. It is suggested that future studies be employed to address some of the issues that emanated from this study, but where not thoroughly investigated, such as an investigation into the role of education coupled with awareness creation in changing the public’s attitude towards renewable energy projects. Additionally, an in-depth study maybe conducted that compares and contrasts the different practices and regulation approaches to public participation in renewable energy projects across different regions and contextual circumstances.Item Habitat, plant communities and threats to the Robertson Granite Renosterveld(University of the Witwatersrand, Johannesburg, 2025-05) Kgomo, Thapelo Josias; Szewczuk, Alekzandra; Dayaram, Anisha; Witkowski, Ed T.F.The Robertson Granite Renosterveld (FRg3) vegetation type is found north of La Colline in the Breede River Valley near Robertson at altitudes of between 250 – 850 m a.s.l. This vegetation type is identified as understudied because of the isolated character of its granite pluton, which made it virtually unknown and led to it being identified as a priority for scientific research. As a result, the current study aims to improve the current understanding of plant communities, important habitat characteristics, threats, and identify dominant and endemic species in the FRg3. To investigate the species composition and communities within the FRg3, 53, 10m x 5m plots were sampled across the vegetation type for cover abundance of all the plant species coupled with environmental variables (altitude, and the ground covers of herbaceous vegetation, litter, bare ground, and rock). In addition, soils (~0-10 cm depth) were tested for pH (KCl), total organic carbon (C), soil texture (sand, silt, and clay), exchangeable phosphorus (P), and extractables of boron (B), sodium (Na), magnesium (Mg), potassium (K), and calcium (Ca). Fire is an important ecological disturbance in the Fynbos biome; therefore, Google Earth Engine (GEE) was explored to assess the fire history (2000-2023) of the FRg3 and map the outputs using image collections from MODIS/061/MCD64A1. The plant communities were classified using dissimilarity hierarchical cluster analysis, which showed that the FRg3 comprises five major plant communities, the following four of these communities are found in fire affected areas: Dodonaea viscosa – Euryops tenuissimus; Dicerothamnus rhinocerotis - Dodonaea viscosa, Passerina obtusifolia–Restio capensis, and Muraltia heisteria – Restio capensis; and the fifth community (Pteronia paniculata–Dicerothamnus rhinocerotis) is found in areas that have not burnt since 2000. The FRg3 had three major fires (2000, 2006, and 2017) over 24 years (2000-2023). In 2000, approximately 35% of the FRg3 burnt, while in 2006 and 2017 the fire burnt approximately 24% and 53% respectively. There have been overlaps in areas burned by multiple fires (2000 & 2017 = 23%; 2006 & 2017 = 22%), and almost half (47%) of the vegetation type did not burn at all over the 24 years. The soil analysis showed significant differences (P ≤ 0.05) in pH, Na, and texture (sand and clay) across the five communities. The FRg3 still retained most (99%) of its natural vegetation in 2023; however, there are disturbances and threats to the vegetation type, such as land clearing for agricultural purposes, and alien invasive plants such as Hakea sericea were observed within the vegetation type in 2023. The 24- year (2000-2023) changes in vegetation structure of the FRg3 were investigated using the Normalized Difference Vegetation Index (NDVI), which was computed from Landsat 5 and 8 over five different time periods (2000 – 2006, 2006 – 2013, 2013 – 2017, 2017 – 2023, and 2000 – 2023). This analysis showed an increase in FRg3 biomass (taller vegetation) between 2000 and 2006, largely because the area that burnt in 2000 had recovered despite the fire in 2006 which only burnt the small northern portion of the FRg3. The FRg3 lost most of its above ground biomass in 2017 due to a fire that burnt over half of it. The FRg3 had the most biomass in 2013 and 2023, likely due to the lack of natural or anthropogenic disturbances.Item Integrated management of Campuloclinium macrocephalum (pompom weed) (Less.) DC. (Asteraceae) in South Africa(University of the Witwatersrand, Johannesburg, 2024-10) Mudau, Phuluso; Byrne, Marcus J.; Witkowski, Ed T.F.; Goodall, JeremyCampuloclinium macrocephalum (Less.) DC. (Asteraceae) is an invasive perennial forb native to Central and South America and known as pompom weed in South Africa. It has since naturalized and poses a threat to grasslands, wetlands and savannas in many parts of South Africa. The weed is listed as category 1b of NEMBA (National Environmental Management Biodiversity Act), an invasive species which must be controlled and wherever possible, removed and destroyed. It causes significant reduction in grazing capacity of farms and game reserves, as it is unpalatable to livestock and wildlife. The weed has a clustered thick tuber-like root system that enables it to withstand fire and harsh winter conditions such as low rainfall and frost. Pompom has increased its invasion range by 671% between 2006 and 2016. Management strategies to date, such as the application of chemical, fire, mechanical and biological control have not yielded substantial results, hence the increase in invasion range of C. macrocephalum. Application of herbicides alone requires multiple annual applications which may not be feasible, logistically or financially. It is also not ideal to continuously apply herbicides in sensitive environments such as areas that are close to streams, wetlands and dams. Three annual applications of metsulfuron methyl and picloram alone were found to suppress the abundance of C. macrocephalum but failed to control the weed. Mechanical control of C. macrocephalum through hoeing or digging is ineffective as damage to rootstocks by splitting them leads to further vegetative growth resulting in an increase in pompom density. Multiple biological control agents are often released against a single invasive plant to improve the degree of control. There are three biological control agents released against C. macrocephalum in South Africa namely, Liothrips tractabilis Mound and Pereyra (Thysanoptera: Phlaeothripinae), Puccinia eupatorii (Pucciniales: Pucciniaceae) and a flower-feeder, Cochylis campuloclinium Brown (Lepidoptera: Tortricidae). Damage inflicted by L. tractabilis and P. eupatorii is moderate, and the degree of control provided by the two agents has not resulted in sufficient control of the weed. A strategy of combining different control methods such as chemical, mechanical, fire or biological control can improve the impact and effectiveness of any combination of the four methods and improve the degree of control of a particular weed. Integrated management of invasive weeds vary to suit a target plant based on invaded habitat, existing control method and management objectives. The first aim of the study (Chapter 2) was to evaluate how burning alone prior to the growing season of C. macrocephalum and burning alongside herbicide application affects the weed density, regrowth/re-sprouting from rootstocks, flowering density and the seedbank of the weed over two growing seasons at Rietvlei Nature Reserve, Gauteng Province, South Africa. The seedbank was estimated by quantifying the number of newly emerging seedlings on each experimental block. During the first growing season (2020-2021) fire in August significantly reduced the seedbank of pompom by over 85% but failed to reduce the density of mature plants within the invaded areas. Herbicide application in December 2020 post fire of the first growing season resulted in over 98% reduction of the weed density during the first growing season. For the second growing season (2021-2022), there was a 9% regrowth from rootstocks of the weed on experimental blocks previously treated with fire and herbicide, which can be managed by a follow up application of herbicide. Integrating fire and herbicide was found to be a successful management strategy and it is therefore recommended as a management approach for the control of pompom weed in South Africa. The impact of L. tractabilis is variable at different sites invaded by C. macrocephalum. This is because L. tractabilis has established in some open grasslands and failed to establish in more mesic environments particularly seasonal wetlands. A sub-lethal dose of herbicide can be used to suppress the reproductive ability of the weed without killing the plant and sustain the biocontrol population. Therefore, the second aim (Chapter 3) was to identify sub-lethal doses of three herbicides (picloram, impala and metsulfuron methyl) that will not kill but suppress the vegetative growth of C. macrocephalum and sustain the L. tractabilis population. However, the identified sub-lethal doses of the three herbicides were found to be incompatible with the agent L. tractabilis, because of an indirect impact on their feeding sites (young and apical stem sections) which affected the abundance of the agent. Due to lack of feeding sites, L. tractabilis was found to feed on old stems which are the least preferred sites. Consequently, considering the indirect impact of sub-lethal doses on L. tractabilis, the use of such doses is not recommended given the incompatibility. In a study in 2018, early season mowing of surrounding vegetation, led to enhanced effectiveness of L. tractabilis on pompom weed, resulting in increased levels of stem deformation by the agent. Campuloclinium macrocephalum in more sunny vegetation (areas with mown short vegetation) experienced increased light intensity and temperatures compared to areas with unmown long vegetation (more shady sites). However, it remains unclear how the physiology and growth rate of C. macrocephalum were affected by the difference in light intensities and temperature and how subsequent changes in plant growth and ecophysiology affected the biocontrol agents. The third aim of this study (Chapter 4) was to evaluate the influence of two light intensities (full sunlight and reduced sunlight) on chlorophyll content, chlorophyll fluorescence, stomatal conductance, and growth of C. macrocephalum, and to assess the reproduction and feeding impact of L. tractabilis in a laboratory trial. Reduced light intensity (shade plants) resulted in higher chlorophyll content, chlorophyll fluorescence, stomatal conductance, growth rate and chlorophyll fluorescence than in sun plants suggesting increased photosynthetic rates. This resulted in a significant increase in growth rate, with greater height of C. macrocephalum in the shade (108 cm) compared to in the sun (72 cm) over seven weeks. The feeding performance and abundance of L. tractabilis was significantly higher in open sun plants. This suggests that light intensity plays a critical role in the performance and establishment of the thrips. Therefore, mowing or burning the surrounding vegetation prior to and post release of the thrips may aid establishment and improve efficacy of the agent. Liothrips tractabilis is known to prefer young apical shoot stems compared to more mature and old stems. To understand why L. tractabilis preferred young stems and plants in short vegetation, the fourth aim of the study (Chapter 5) was to evaluate and compare the nutritional quality of young apical stems compared with old stems (mid-section) of C. macrocephalum that grew in long and short vegetation by assessing the nitrogen and carbon levels and C:N ratio. Nitrogen content was greater in apical stems than in mid-section stems from short vegetation, suggesting better nutritional quality for L. tractabilis compared to plants from long vegetation. Therefore, the surrounding vegetation has an impact on the nutritional quality of C. macrocephalum which affects the performance and population size of L. tractabilis. In conclusion, neither fire alone nor herbicide alone significantly reduce the population density of pompom weed, but the application of lethal herbicide to C. macrocephalum after fire proved to be the most effective control method.Item Examining intraspecific ploidy variation and functional traits that facilitate the environmental distribution of the Drakensberg near-endemic species, Rhodohypoxis baurii (Baker) Nel. var. platypetala Hilliard & Burtt(University of the Witwatersrand, Johannesburg, 2024-09) Mtileni, Masingitla Promise; Glennon, Kelsey I.Polyploidy is widely acknowledged as a key feature of evolution in flowering plants. Polyploidy often leads to reproductive isolation between polyploids and their diploid progenitors. This can arise via morphological and habitat differentiation, with polyploid plants often exhibiting increased growth, survival, and reproductive output under different environmental conditions. However, whether polyploidy drives general ecological divergence between diploids and polyploids or confers an advantage for plants under different environmental conditions remains an open question. Polyploids are generally thought to have an increased adaptive potential to populate areas that are increasingly environmentally ‘extreme’. These ‘extremes’ can be described as experiencing the extreme end of an environmental variables; either colder or hotter temperatures, drier or wetter habitats, increased UV exposure, or increased/decreased seasonality. The ability of polyploids to acclimate to these ‘extremes’ may be a consequence of the beneficial outcomes of polyploidy, such as intrinsically higher heterozygosity and altered gene expression. My thesis examines how environmental variables may shape the distribution of plants with different ploidies, the association of polyploidy with plant morphotypes, and whether plants with different ploidy levels respond distinctively to different environmental conditions. Using a meta-analysis, I examined the hypothesis that there is consistent segregation between diploid and polyploid plants based on elevation. I found that the perceived trend of polyploids occurring at significantly higher elevations than diploids was not supported for 71% of the sampled 28 studies. In addition, climate variables, soil moisture, and geographic region only explained 0.3% of polyploid presence at the highest elevations across studies. Next, I conducted a cytogeographic study, growth chamber and greenhouse experiments, and reciprocal transplants to examine ploidy level distribution and the association of polyploidy with the responses of plants to different environmental conditions at the population level. I focused on Rhodohypoxis baurii var. platypetala (Hypoxidaceae), a Drakensberg nearendemic taxon. I found evidence for both habitat and morphological differentiation between diploid and tetraploid populations, where tetraploids had larger leaves and larger flowers and generally occurred at lower elevations in warmer and drier habitats with soil that is marginally higher in nitrogen and phosphorus concentration than diploid habitats. Only one mixed-ploidy population (diploids and triploids) was found. My findings suggest that a higher ploidy level was not associated with larger morphological traits or increased reproductive output under greater soil nitrogen, phosphorus, and salinity levels, nor greater survivorship and increased reproductive output under higher salinity, or after being transplanted. Together, findings from this thesis dovetail with collective findings from other work where increased ploidy was not found to confer an advantage or limitation under different environmental conditions, and where the general relationship between environmental variables and polyploid distribution was found to be indirect or negligible. Work at large scales (e.g., broad scale and at a global level) may reveal meaningful polyploid patterns that may not be evident at smaller scales. However, such work may not be accurate when predicting the role of polyploidization in plants generally or outlining the general biogeographic principle of polyploid distribution due to the lacking historical component which prevents us from inferring nascent drivers of observed distributions. Broad comparative work should be complemented with robust experimental studies (e.g., reciprocal transplants and common garden experiments). Comparing niches of diploid and polyploid populations from the same species may also be more useful in identifying unifying trends than comparing niches of polyploid species across the globe.Item Costs and benefits of solitary living in the bush Karoo rat (Otomys unisulcatus)(University of the Witwatersrand, Johannesburg, 2024-10) Makuya, Lindelani; Pillay, Neville; Schradin, CarstenSolitary living has traditionally been regarded as the ancestral as well as most common and most primitive form of social organisation in mammals. However, recent comparative studies indicate that solitary living is not ancestral for all mammalian orders, and that solitary living is an adaptation to the environment. I show that solitary living occurs in only 22% of studied mammalian species and argue that the main benefit of solitary living is to avoid the costs of group-living. Group-living has been explained using socio-ecological models, and I used the same factors of resource distribution and predation risk to develop a socio-ecological model explaining solitary living. To reach a better understating of solitary living, I studied the social system of free-living bush Karoo rats (Otomys unisulcatus) in the Succulent Karoo semi-desert of South Africa. I used trapping and marking, focal animal observations and mini-GPS dataloggers that I fitted simultaneously to neighbouring females. I found that 96% of female bush Karoo rats were solitary living, with social groups of two or three individuals occurring occasionally. Groups always consisted of close kin, typically females. The home ranges of kin neighbours overlapped more than those of non-kin. Neighbours were, however, attracted to the same foraging grounds, irrespective of relatedness. Females tolerated one another at shared foraging grounds, which could be interpreted as byproduct mutualism, a simple form of cooperation. I recorded interactions between neighbouring bush Karoo rats both in a neutral test arena and in the field to investigate whether solitary living was due to aggression and social intolerance. Social interactions between neighbours were rare and aggression was rare in neutral arena tests. However, female bush Karoo rats were more aggressive towards non-kin intruders in the field tests. Finally, the relationship between mother and offspring remained amicable even after the offspring had dispersed from the lodges, indicating that maternal aggression was not the mechanism that led to offspring dispersal and solitary living. In conclusion, I showed that solitary living is not always characterised by aggression and avoidance, but rather that solitary species can have non-random and individualised social interactions that are influenced by kinship.Item Mining company governance and the spectre of environmental prosecutions: Is there any deterrent effect?(University of the Witwatersrand, Johannesburg, 2024-10) Monoke, Kwena Martha; Field, Tracy-LynnSouth Africa has developed good environmental legislation, but compliance with these laws is still a challenge (Linde, 2006; Skosana, 2019). According to (Digby, 2016), the South African mining industry has a notorious legacy of inadequate rehabilitation and partially closed mine sites. Mining company directors are the custodians of the company governance and have a duty to ensure compliance with all relevant mining legislation (Bezuidenhout, 2018). Their failure to comply with the law triggers, in many instances, a criminal infraction. All South African environmental legislation relies on criminal penalties to enforce its prescriptions and to punish its offenders (Murombo and Munyuki, 2019). South Africa has strict criminal sanctions for environmental noncompliance and degradation (Truter, 2014). The awareness of South Africans with regards to environmental crimes has increased due to initiatives such as the annual National Environmental Compliance and Enforcement Report, and online judgment archives such as the South African Freedom of Legal Information Institute (SAFLII) and Juta Law (Department of Forestry, Fisheries and the Environment, 2023a). The State v Blue Platinum Ventures and Mr Maponya case was used as a case study. This study seeks to investigate whether the threat of environmental prosecution influenced the mining company governance and its director and whether it had any deterrent effect on the company’s commission of environmental crimes. A qualitative case study approach was undertaken. Several documentary sources of information were relied on for the analyses of the Blue Platinum case and interviews were conducted to fill in the gaps from the data analyses. It was determined that the rule of law was being put into practice and that the community had received justice because rehabilitation was conducted and it addressed their concerns. The Blue Platinum Ventures and Mr Maponya case has had a deterrent effect on the company itself and Mr Maponya.Item Investigating hybridization among high altitude Rhodohypoxis species in the Drakensberg Alpine Centre(University of the Witwatersrand, Johannesburg, 2024-07) Coetzer, Dewald Janus; Glennon, Kelsey L.Putative hybridization between the alpine Rhodohypoxis taxa (R. baurii var. confecta, R. deflexa, R. rubella, R. incompta, and R. thodiana) as well as Hypoxis parvula var. parvula has been documented in the wild – suggesting that there are few genetic barriers between these taxa that often grow in sympatry. This study aimed to assess patterns of hybridization among the alpine Rhodohypoxis species and between them and H. parvula var. parvula at three different natural study sites and to contribute new data that might help delineate/solidify genus and species boundaries in this group using morphometric analysis, seed surface micromorphological comparisons, microsatellite data, and controlled greenhouse crosses. It was found that although all the methodologies were congruent in their ability to delineate the Rhodohypoxis species from one another and from H. parvula var. parvula (thereby corroborating their current circumscription), substantial admixture was detected at each of the three study sites – and admixed individuals were largely morphologically cryptic. Furthermore, morphometric analysis and seed surface micromorphology could not distinguish between R. thodiana and putative hybrid taxa – suggesting it may be of hybrid origin. The present study also reports the complete self-incompatibility of polyploid H. parvula var. parvula, the facultative self-compatibility of diploid R. baurii var. confecta, the successful crossbreeding of these two taxa from Sentinel Peak with a strong asymmetrical barrier to gene exchange, and a mechanism involving double-reduced polyploid pollen facilitating this interploidy cross. Low germination rate of the resulting hybrid seed is consistent with a decrease in F1 viability. These findings, coupled with the low incidence of polyploid H. parvula var. parvula individuals producing double reduced pollen, and the low levels of admixture detected, suggesting substantial post-pollination reproductive isolation between these two taxa. Nevertheless, caution should be taken when making strong taxonomic inferences from phylogenies that include R. baurii var. confecta and H. parvula var. parvula representatives from the Sentinel Peak study site.