Modernisation and extension of InetVis: a network security data visualisation tool
- Authors: Johnson, Yestin
- Date: 2019
- Subjects: Data visualization , InetVis (Application software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69223 , vital:29447
- Description: This research undertook an investigation in digital archaeology, modernisation, and revitalisation of the InetVis software application, developed at Rhodes University in 2007. InetVis allows users to visualise network traffic in an interactive 3D scatter plot. This software is based on the idea of the Spinning Cube of Potential Doom, introduced by Stephen Lau. The original InetVis research project aimed to extend this concept and implementation, specifically for use in analysing network telescope traffic. The InetVis source code was examined and ported to run on modern operating systems. The porting process involved updating the UI framework, Qt, from version 3 to 5, as well as adding support for 64-bit compilation. This research extended its usefulness with the implementation of new, high-value, features and improvements. The most notable new features include the addition of a general settings framework, improved screenshot generation, automated visualisation modes, new keyboard shortcuts, and support for building and running InetVis on macOS. Additional features and improvements were identified for future work. These consist of support for a plug-in architecture and an extended heads-up display. A user survey was then conducted, determining that respondents found InetVis to be easy to use and useful. The user survey also allowed the identification of new and proposed features that the respondents found to be most useful. At this point, no other tool offers the simplicity and user-friendliness of InetVis when it comes to the analysis of network packet captures, especially those from network telescopes.
- Full Text:
- Date Issued: 2019
Narratives and home: remembering an almost forgotten walk
- Authors: Bezuidenhout, Natasha Belinda
- Date: 2019
- Subjects: Home in literature , Home in art , Artists -- South Africa
- Language: English
- Type: text , Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/115039 , vital:34072
- Description: The title of my exhibition Bittersoet alludes to the self-exploratory nature of my practice, as I interrogate the personal memories associated with objects that characterise the relationship between myself and my mother (mamma). This supporting document, Narratives and Home: Remembering an almost forgotten walk, considers the key conceptual concerns informing my practice. In this mini-thesis, I address the question: ‘What is a home?’. Drawing from my own Fine Art Practice, I explore how home can be examined as a product of the imagination, rather than only as a physical place. I consider how ‘home’ is constructed as the primary objective within an ideological framework defined by history, memory and narrative. Engaging beyond the idea of ‘home’ as a fixed structure or place, I examine the idea of ‘home’ as something fluid that is negotiated and defined by the interaction between objects and language. It is concerned with dialectics of memory and narrative as they pertain directly to an experience of both searching for and reimagining home through metaphorical representations. In particular, I explore how home can be seen as equally familiar and unfamiliar, existing in-between, always changing, never fixed, rather in a constant state of flux. The concept of home is addressed in a dialogical process by using Afrikaans as my mother tongue, I narrate informal conversations between myself and my mother. These conversations transform and expand into hybrid words, memories and narratives to form a layered continuous dialogue between my practice and research. This notion relates to exploring oneself and the ‘fictions’ of the past. The self being fundamental to the individual comprehension of both ‘place’ and ‘space’.
- Full Text:
- Date Issued: 2019
National debt and sovereign credit ratings
- Authors: Orsmond, Daniel
- Date: 2019
- Subjects: Debts, Public -- South Africa , Credit ratings -- South Africa , Gross domestic product -- Africa , Inflation (Finance) -- Africa , Economic development -- South Africa , Economic history , Macroeconomics , Moody's Investors Service , Standard and Poor's Ratings Services , Fitch Ratings (Firm)
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/115160 , vital:34083
- Description: In recent years South Africa’s foreign and local denominated debt has been downgraded by the three major global credit agencies, Moody’s, Standard and Poor’s (S&P) and Fitch. The foreign debt has been downgraded to speculative grade or ‘junk’ status by all three agencies. Local debt has been downgraded to ‘junk’ by S& P and Fitch, but Moody’s currently maintains local debt at the lowest level of investment grade. Many economists believe that South Africa’s rapidly rising debt levels are the major contributor to the decisions to downgrade South Africa’s debt. Yet many countries with higher levels of debt continue to be rated investment grade. Clearly, factors other than the actual level of debt are important in determining the credit rating agencies’ rating decisions. The literature suggests several variables are important in determining a country’s sovereign credit rating. These variables include not just the ratio of government debt to gross domestic product, but also a country’s real growth rate, inflation, gross domestic product per capita, external balance to gross domestic product, default history and the level of economic development. In examining the proposition that it is not a country’s debt level per se that matters, but rather the dynamics surrounding that debt, this research also includes three additional variables that are not usually mentioned in the literature. These, based on van der Merwe (1993), are the real GDP growth rate less the real interest rate, the ratio of the fiscal balance to GDP, and the ratio of government interest payments to government expenditure. The purpose of this addition is to examine whether rather than a country’s debt level (debt to GDP variable), it is the sustainability of a country’s ability to service debt, as indicated by the three additional ‘debt dynamic’ variables, that is most important when determining sovereign credit ratings. Panel data analysis for a sample of 12 countries over the period 1996Q1 to 2017Q4 indicates that of the broad macroeconomic variables mentioned in the literature, government debt to GDP, the real growth rate, inflation (cpi), and default history are all statistically significant, with the coefficients having the correct signs in all specification of the model, with the exception of the real growth rate in Models 2 and 3. With regards to the debt dynamic variables, the real growth rate less the real interest rate, as well as the interest payments to government expenditure variables are found to be significant determinants of sovereign credit ratings. Thus, the findings of the research suggest that the level of debt alone is an inadequate determinant of sovereign credit ratings. The dynamics of debt along with other macroeconomic variables are also important determinants of a country’s credit rating. Concerning policy recommendations, it is evident that debt sustainability is important for sovereign credit ratings. Evidence of the direct importance of economic growth in determining credit ratings is mixed, but growth is a key driver of debt dynamics variables and therefore of ratings. This suggests that policy should focus on stimulating growth to reduce the gap between real growth and real interest rates as well as increasing the denominator of the debt to GDP ratio and increase the size of the tax base, which would improve government’s ability to service the interest payments on its debt.
- Full Text:
- Date Issued: 2019
Ndonakele
- Authors: Ngcelwane, Ayabulela
- Date: 2019
- Subjects: Xhosa fiction , Xhosa poetry
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92721 , vital:30742
- Description: Le thisisi yingqokelela yemibongo egxile kwimingeni ejamelene noluntu kwimimandla efana neelokishi. Unobangela wale mingeni yintswelo-ngqesho, ukungafumani zindlu, ubundlobongela, isimo sezepolitiki, njalo-njalo. Imisebenzi kaRonnie Kasrils ngakumbi kwincwadi yakhe ethi A simple man, uRustum Siyongwana – Ubulumko bezinja uS. S. Mema – Umnxeba Wobomi, nezinye, zibe nefuthe kakhulu kule thisisi. Indlela abasebenzisa ngayo ulwimi lwemihla ngemihla, maxawambi bade basebenzise nesakhono esisetyenziswa ezintsomini ezifana nokusebenzisa abalinganiswa abazizilwanyana bekwekwa umba onobuzaza. Injongo yalo msebenzi kukugqamisa ukubaluleka kwentlalontle yoluntu, nokuvuselela isazela koongxowa ayibotshwa. Yiyo loo nto kuzanywe kangangoko ukusetyenziswa ulwimi olunokufikeleleka nakubani na. , English and Xhoxa versions provided for dual language submission
- Full Text:
- Date Issued: 2019
Ndoxoza mphini wumbi!
- Authors: Saki, Sandile Dudu
- Date: 2019
- Subjects: South African fiction (English)
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92605 , vital:30741
- Description: My English half-thesis comprises semi-autobiographical short stories based on my own lived and observed experiences of patriarchal township life, but told through the eyes of others, often those who find themselves victims of societal ills and cruel injustices. The stories deal with issues ranging from rape culture, intimate femicide, social patriarchy and the vulnerability of women, children and people living with disabilities in such settings. Refusing didacticism, I seek to voice the complexity, bravery and beauty of my characters. I draw influence from Joel Matlou’s simple narration of the small details of daily life, Can Themba’s ability to find humour in the everyday, Chimamanda Ngozi Adichie’s contemporary sass and Irenosen Okojie’s unconventional, subtle and deeply enigmatic approach to storytelling. , Le thisisi yingqokelela yemibongo enesingqi nefuthe endilincance kubabhali endihlangene nabo kwezi zifundo endingabala kubo uMxolisi Nyezwa, Rustum Kozain nabanye. Injongo yale thisisi kukonwabisa; ukucebisa mhlawumbi ukuthungulula iintongo emva kobentlombe. Maxa wambi ikukukhahlela nakwabo baye banegalelo kwizinto-yinto zokuhlala ngakumbi iimvumi zikaMasikhandi ezifana noMlindelwa ‘Inkunz’ emdaka’ Mralatya owaziwa njengovulindlela kaMasikhandi kwisizwe sakwaXhosa siphela. Bakho ke ababhali abasingqi sabo sindithimbileyo, naba bugcisa ndibuthandileyo endingabalula kubo uMzwandile Matiwana, M. S. Mlandu, Fundile Majola, John Solilo, J. J. R Jolobe kunye noS. E. K. Mqhayi. Liyavakala ifuthe labo kule mibongo, ngakumbi isingqi nokusetyenziswa kolwimi. , English and Xhosa versions provided for dual language submission
- Full Text:
- Date Issued: 2019
Negotiating spaces, constructing identities and consuming symbolic resources: examining the complex interplay between identity formation, context and media consumption amongst black South African students at Rhodes University
- Authors: Willetts, Luke
- Date: 2019
- Subjects: Mass media -- Psychological aspects -- South Africa -- Makhanda , Mass media -- Social aspects -- South Africa -- Makhanda , Mass media -- Sociological aspects -- South Africa -- Makhanda , Mass media and culture -- South Africa , Mass media and race relations -- South Africa , Social movements -- South Africa -- Makhanda , Student movements -- South Africa -- Makhanda , Male college students -- South Africa -- Makhanda , Rhodes University -- Students -- Attitudes
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/95207 , vital:31127
- Description: This thesis has looked at the complex interplay between media consumption and identity formation amongst a group of black South African male students within the context of a racially homogenous communal viewing area located on the Rhodes University campus during the #FMF protests in 2016. Using qualitative research methods the study concluded that the group context of communal viewing helped the students structure and make sense of their daily lives. They actively divorced themselves from the main student populace in an attempt to escape lived experiences of a repressive institutional culture expressed through the university’s monolingual language policies, aesthetics and course material. These students embodied the characteristics of a diasporic community characterised by displacement, dispersal and the continuous re-articulation of differences across contradictory social, cultural and economic contexts. They grappled with an alienating environment by creating a safe space for cultural reproduction aided by the communal consumption of local television programmes. Preferences for local content broadcast in African languages were shaped by a linguistic marginalisation experienced on the Rhodes campus. The politicisation of the context through #FMF in turn politicised the students’ subjectivities leading to a need to be informed of the movement’s progression through evening news broadcasts. Discussions around campus life were dominated by #FMF and the collective experiences of marginalisation in and from the university space. Communal viewing of local television shows allowed this group of students to transcend decades of essentialised African ethnic divisions bringing forward a group identity premised on a lived hegemony signified by blackness.
- Full Text:
- Date Issued: 2019
Petrography and geochemistry of the Masoke Iron Formation and its associated ferruginous counterparts, kanye basin Botswana
- Authors: Nkabelane, Ndifelani Oriel
- Date: 2019
- Subjects: Petrology -- South Africa , Geochemistry -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115221 , vital:34101
- Description: A sequence of Transvaal Supergroup sediments extends into southern Botswana beneath Kalahari cover as the Kanye basin, these are known to host billions of tons @ 60>Fe. Masoke Iron Formation (Kanye Basin) which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The Palaeoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa hosts high grade (>60% Fe) hematitic and specularitic iron and manganese mineralisation. It is therefore important to study and record the petrographic, mineralogy and geochemistry of Masoke Iron Formation, compare the results to the much known Kuruman and Griquatown Iron Formations. This study systematically investigate and record the petrography, mineralogy and geochemistry of all Masoke Iron Formation of Taupone Group in the Kanye Basin, which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The further objective is to compare Masoke Iron Formation to the equivalent units in the Transvaal basin and Griqualand basin. In contrast to both Transvaal and Griqualand West Basin the Masoke iron Formation (Kanye Basin) has not been the subject of systematic scientific investigations. The study covers three main areas in the Kanye Basin: Keng Pan Area, Ukwi/Moretlwa hill and Janeng Hill Area. The mineralogy and geochemistry of these areas are presented in this study. Kanye Basin has a potential to host a large iron ore deposit, the geological setting in this area incorporates many of the elements necessary for iron ore formation. These include: banded iron formation (BIF), major unconformities with prolonged periods of weathering, carbonate sequences etc. In addition, several large deposits and mines are known from this area. This area can potentially have both hypogene and supergene enrichment of BIF. In this model, prospectively for new deposits is a function of the following: presence of iron formation units, proximity of mapped Asbestos Hills and Voëlwater BIF, thrust faulting (as indicated by the aero-magnetic interpretation), duplication of the ore horizon by folding, intersection of the BIF by major extensional fault, proximity of Olifantshoek/Waterberg outcrop, Gamagara unconformity, presence of carbonates (dolomites) and thin Kalahari sand cover. Major BIF units in the area of study include: the Masoke Iron Formation, equivalent to Kuruman Formation of the Asbestos Hills Subgroup, the Rooinekke iron formation of the Koegas Subgroup and the Hotazel Formation of the Voëlwater Subgroup. Supergene enrichment of these BIFs may occur wherever they are overlain by a major regional unconformity. The base of the Waterberg and the OlifantshoekSupergroups represent major unconformities in this regional target area. Potential for hypogene deposits is indicated by faulting (preferably extensional) proximal to BIF.
- Full Text:
- Date Issued: 2019
Photocatalytic treatment of organic and inorganic water pollutants using zinc phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates
- Authors: Mapukata, Sivuyisiwe
- Date: 2019
- Subjects: Phthalocyanines , Cobalt ferrite , Zinc , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67603 , vital:29119
- Description: This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
- Full Text:
- Date Issued: 2019
Photophysicochemical properties and surface-enhanced Raman scattering of phthalocyanine-nanoparticle conjugates
- Authors: Nwahara, Nnamdi
- Date: 2019
- Subjects: Boron compounds , Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Raman effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71647 , vital:29928
- Description: This work presents the synthesis, photophysical and photochemical characterization of a series of metallophthalocyanines (MPcs) and boron dipyrromethene (BODIPY) and their conjugates with either gold or silver nanoparticles (AuNPs or AgNPs) or graphene quantum dots (GQDs). The rich π-electron systems of GQDs and MPcs employed in this work enabled the coordination of MPcs to GQDs (either as pristine or modified) via the non-covalent (π-π stacking) method. GQDs, AuNPs and AgNPs were also functionalized with L-glutathione (GSH) in order to assist coupling to the Pcs or BODIPY dye. Spectroscopic and microscopic studies confirmed the formation of the respective nanoparticles (NPs) as well as the conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines (Pcs) or BODIPY alone. This work also shows that the incorporation of folic acid (FA) into Pcs-NPs composites leads to further enhancements in the singlet oxygen generation capabilities of the resulting conjugates, and so experimentally demonstrates for the first time, a synergy between FA and the respective nanoparticles (GQDs, AuNPs and AgNPs) in affecting the photophysical properties of Pcs complexes. GQDs and Pcs/GQDs hybrids were also herein decorated with AuNPs – metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies. These nanostructures herein reported, have been shown to possess enhanced light-matter properties, enabling unique surface-enhanced Raman scattering (SERS) behaviours, with unprecedented enhancement factors of up to 30-fold. This work therefore, reports on the fabrication of Pc/GQDs/AuNPs hybrids and experimentally demonstrates their incredible potential as novel Raman-active PDT agents.
- Full Text:
- Date Issued: 2019
Popular politics in the rural Western Cape, South Africa: a case study of Ruiterbos
- Authors: Ghedi Alasow, Jonis
- Date: 2019
- Subjects: Political participation -- South Africa -- Cape Town , South Africa -- Politics and government -- 1994- , Land tenure -- Political aspects -- South Africa , Land use, Rural -- Political aspects -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/96165 , vital:31246
- Description: This thesis argues that the philosophical foundations upon which human beings have been engaged have, across various schools of thought, made the mistake of presuming that some people are more modern than others. This suggestion is refuted throughout this thesis. To do this, intellectual traditions that take the fundamental rationality of all human beings as an indispensable starting point are engaged to argue for the need to acknowledge that everyone in the ‘now’ is indeed, of the ‘now’. This thesis connects these debates about modernity, rationality and humanity to the contemporary discussions around rural politics with particular reference to Ruiterbos in the Western Cape province of South Africa. By means of detailed empirical and ethnographic research, this thesis illustrates the issues around which people in Ruiterbos are politicised. Via this case study, the a priori assumption that rural politics will necessarily manifest itself only with respect to questions of land and agrarian reform or labour relations is complicated. The two issues around which people in Ruiterbos, during the time of this research, seem to be politicised – housing and education – are surfaced throughout this thesis. The thesis argues that the findings in this case study call for an expansion of the issues that are traditionally considered when the question of rural politics is raised. The often historicist approach that limits the possibilities for politics in rural areas should be suspended for an approach that takes popular politics and political agents in rural areas seriously. The thesis finally argues that the conclusions that are reached with respect to questions of modernity and rural politics ought to be adopted to allow for more detailed and thorough explanations of popular politics in places like Ruiterbos.
- Full Text:
- Date Issued: 2019
Post-release evaluation of Megamelus scutellaris Berg. (hemiptera: delphacidae): a biological control agent of water hyacinth Eichhornia crassipes (Mart.) Solms-Laub (Pontederiaceae) in South Africa
- Authors: Miller, Benjamin Erich
- Date: 2019
- Subjects: Megamelus scutellaris Berg. , Delphacidae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92330 , vital:30710
- Description: Water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae) is a free-floating aquatic macrophyte from South America that was introduced to South Africa in the 1900s for its attractive ornamental flowers. The plant was classified as a serious invader in the country in the 1970s, eventually becoming the worst invasive aquatic plant in South Africa. Biological control is widely regarded as the most effective method of managing water hyacinth, as it is ecologically safe, cost-effective, and self-sustaining. To date, nine biological control agents have been released in South Africa against water hyacinth, including eight arthropods and a pathogen. Due to the cumulative effects of highly eutrophic waterbodies, which mitigate the damage caused by biological control, and the cold winters which inhibit the rate of biological control agent population build up, South Africa currently has more biological control agents released on water hyacinth than anywhere else in the world. The need for a cold-tolerant agent that can reproduce and develop quickly, while still being damaging to water hyacinth in eutrophic systems, led to the introduction of the most recently released water hyacinth biological control agent, the planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae), which was initially collected from Argentina. This thesis formed the first post-release evaluation of M. scutellaris since its release in South Africa in 2013. It included a greenhouse experiment to measure the agent’s feeding damage in relation to different nutrient levels and stocking rates, as well as a field component to evaluate both the post-winter recovery of M. scutellaris, and a nationwide survey to measure the establishment of the agent around the country in relation to climate, water quality, and plant health. In the greenhouse experiment, the feeding damage was quantified using measurements of plant growth parameters and chlorophyll fluorometry. It was found that, like other biological control agents of water hyacinth, M. scutellaris was most damaging when released in high numbers on plants grown at medium nutrient levels, and less effective on plants grown at elevated nutrient levels. A water hyacinth infestation on the Kubusi River was selected for the evaluation of the post-winter recovery of M. scutellaris. The Kubusi River is both the first site where M. scutellaris was released, and the coldest site where water hyacinth biological control agents have established successfully in South Africa. Monthly visits tracking seasonal plant health characteristics and agent population densities indicated that the populations of M. scutellaris were impacted most significantly by the season. Low temperatures led to the water hyacinth plants being of poor quality during the winter, which had a subsequent negative effect on the agent populations. The agents could only fully recover by late summer, which meant that the plants were without any significant biological control through the initial phases of the growing season, when they were most vulnerable, and a significant lag-phase occurred between the recovery of the plants and the recovery of the agent population after the winter bottleneck. A survey of all sites where M. scutellaris had been released in South Africa yielded 16 sites where the agents had successfully established, having survived at least one full winter. Among these sites were four sites where the agents were found without them having been released, indicating that they can disperse unaided to new sites. The temperature was a major factor responsible for the success or failure of establishment, with very few agents surviving in the hot areas of South Africa or in areas with a high frost incidence. The density of M. scutellaris was higher in nutrient-rich water, and on plants with more leaves, suggesting that the quality of the plants also contributed to establishment. The results of this thesis showed that M. scutellaris is able to establish successfully in South Africa, and that the agents are capable of causing significant damage to water hyacinth, making it a promising addition to the biological control programme. Novel methods of measuring subtle insect feeding damage in plants and quantifying agent populations are also discussed, along with suggestions for the future implementation of M. scutellaris in South Africa.
- Full Text:
- Date Issued: 2019
Psychotherapy in post-colonial SA: exploring attitudes, views and beliefs of rural ‘black’ communities on psychotherapy
- Authors: Mthembu, Thembekile Thobeka
- Date: 2019
- Subjects: Black people -- Attitudes -- South Africa , Black people -- Psychology -- South Africa , Black people -- Mental health -- South Africa , Psychotherapy -- South Africa , Client-centered psychotherapy -- South Africa , Rural families -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/71419 , vital:29847
- Description: The appropriateness and effectiveness of the field of psychology and its branch psychotherapy has been met with fierce criticisms especially in contexts outside of Western or Euro American or urban Southern Africa. This thesis explores attitudes, views and beliefs of rural ‘black’ communities on psychotherapy (the healing process of the mind and soul). It is important to understand how the healing process of the mind and soul is constructed and practised in South African black rural communities, and this remains an imperative of psychology. The study takes an exploratory qualitative research approach. Nine participants from two rural communities in Kwa-Zulu Natal were interviewed through face-to-face semi-structured interviews. Thematic analysis was utilised as a method of data analysis. The study employed social constructionism and Afrocentricity as theoretical points of departure. The findings were understood through employing Afrocentricity theory underpinned by post-colonial theory. Four main themes were derived with supporting subthemes. The themes indicate that rural black communities’ attitudes, views, and beliefs on psychotherapy are at variance with the Western perspective of psychotherapy. This is further associated with the practise of psychotherapy in rural black communities. The findings of this study can possibly assist in new understandings of psychotherapy as constructed in different contexts and instigate future research to be conducted in often-neglected areas such as rural communities.
- Full Text:
- Date Issued: 2019
Re-surveying the insectivorous bats of northern Kruger National Park, South Africa
- Authors: Brinkley, Erin Reed
- Date: 2019
- Subjects: Bats -- South Africa , Bats -- Behavior , Bats -- South Africa -- Ecology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115697 , vital:34216
- Description: With over 1,300 known species, the order Chiroptera makes up about 20 percent of all mammalian species. Due to its sub-tropical climate, the northern part of Kruger National Park (KNP) in South Africa is believed to have the highest bat species richness in the country. However, the last comprehensive assessment of bat diversity in the region was conducted more than 30 years ago. In 2017 and 2018, I undertook the first detailed re-assessment of the bat communities of the northern KNP since the early 1980’s. I used both live-capture (harp traps and mist-netting) and acoustic technology (SM2 and SM4 Songmeters, Wildlife Acoustics. MA, USA) to sample bats at 24 sites across the northern region of KNP. Through live-capture (336 trapping hours), 155 bats representing 13 species from five families were recorded including Cloetis pervicali, which has never been recorded within the borders of the KNP before. The echolocation calls of all captured bats were recorded to develop a site-specific call reference library that was used (in combination with existing reference calls) as a guide for the identification of bat calls recorded using the acoustic detectors set across 24 sites (278 sampling nights). The acoustic monitoring identified 22 species from six families and two unknown sets of calls. Compared to the historical data of 40 documented species (collected over a 30-year period), the current survey (27 species) resulted in a lower species richness. However, this is likely due to the lower overall sampling effort during my survey. By re-surveying the bats of northern KNP, I have contributed towards an overall bat species inventory for this region. In addition, I have generated an important baseline dataset for the future monitoring of bat diversity across the KNP. Due to bats being important biological indicators, increased research on the various species and their behaviours is essential for improving our understanding of climate change effects as well as the overall health of the environment, especially in protected areas.
- Full Text:
- Date Issued: 2019
Recontextualisation of biodiversity knowledge in the Senior Phase Natural Sciences curriculum
- Authors: Mmekwa, Makwena
- Date: 2019
- Subjects: Science -- Study and teaching (Secondary) -- South Africa , Biodiversity -- Study and teaching (Secondary) -- South Africa , Environmental protection -- South Africa , Biodiversity Conservation -- South Africa , Millennium Ecosystem Assessment (Program) , South African National Biodiversity Institute. Life: the state of South Africa's biodiversity
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/92694 , vital:30723
- Description: This study explored the nature of biodiversity knowledge in the Senior Phase Natural Sciences curriculum in relation to international and national scientific documents. Significant biodiversity key features were identified from a review of these documents. These concepts were then explored in terms of how they had been presented and recontextualised in the Senior Phase Natural Sciences CAPS policy document and a selection of three commonly used textbooks for this subject in South Africa. Using Bernstein’s (1990) framework of the Pedagogic Device, the study traces how biodiversity knowledge was de-located from the scientific Field of Production (FOP) and relocated into the Official Recontextualisation Field (ORF) and Pedagogical Recontextualisation Field (PRF). In exploring the continuity, changes and discontinuities in the biodiversity content, as it has been recontextualised, the study utilised Bernstein’s concepts of selective appropriation and ideological transformation. The study is a qualitative case study that drew on document analysis and structured interviews to generate data. Data analysis for this study consisted of two phases. Phase One involved an analysis of biodiversity knowledge in the Millennium Ecosystem Assessment (MEA, 2005) and Life: The State of South Africa’s Biodiversity (SANBI, 2013) which represented the FOP. This was in order to explore the nature of biodiversity knowledge in those documents. This knowledge was then compared to the Senior Phase Natural Sciences curriculum which represented the ORF and selection of textbooks representing the PRF. Phase Two sought to investigate the role players in the recontextualising fields and what roles did they play in the recontextualisation of biodiversity knowledge. This phase entailed an analysis of interviews. The findings showed that both the international document and the national document presented biodiversity knowledge in terms of their fundamental value to humans. In addition, these documents illustrated human-environmental interactions. They presented procedural knowledge that allow us to understand ecosystems and their services to human well-being. The documents also described how ecosystem services are in decline in many places around the world. The documents presented knowledge of threats to biodiversity such as habitat loss, invasive species, pollution, and overharvesting. They also included knowledge of conservation and sustainability which focused on preventing ongoing degradation and restoration and reversal of degradation of ecosystems. In comparing the ORF and the PRF this study showed that the CAPS policy document appears to present concepts foundational to understanding biodiversity rather than discussing biodiversity itself. The textbooks contextualise these foundational concepts and broaden them mostly through pictorial illustrations, as case studies and contextual examples. A recommendation from the research is that the official recontextualisation process should review opportunities to draw on international and national documents that present concepts and contemporary cases of biodiversity content knowledge to ensure that the complexities around biodiversity are presented in the curriculum. This study may contribute to the development and review of the Natural Sciences curriculum and environmental education in South Africa. The study also suggests areas of biodiversity knowledge that might be included as curriculum content in the future. It further suggests that curriculum developers consider including new environmental knowledge which deals with local, national and global needs and expectations.
- Full Text:
- Date Issued: 2019
Recovery and molecular identification of Aichi virus 1, enteric human bocaviruses and enteric human adenoviruses in untreated sewage and mussel samples collected in the Eastern Cape Province of South Africa
- Authors: Onosi, Oikwathaile
- Date: 2019
- Subjects: Sewage -- Analysis -- South Africa -- Eastern Cape , Sewage -- Microbiology -- South Africa -- Eastern Cape , Viral pollution of water -- South Africa -- Eastern Cape , Sewage disposal in rivers, lakes, etc. -- South Africa -- Eastern Cape , Enteroviruses -- South Africa -- Eastern Cape , Picornaviruses -- South Africa -- Eastern Cape , Aichi virus 1 , Parvoviruses -- South Africa -- Eastern Cape , Adenoviruses -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69456 , vital:29539
- Description: Gastroenteritis, commonly known as diarrhoeal disease, is one of the top killers responsible for substantial human morbidity and mortality especially in third world countries where most people do not have access to potable water and where hygiene levels are low. Many bacterial, viral and protozoal agents are known causes of gastroenteritis and viral gastroenteritis is responsible for over 70% of cases. Rotaviruses are the main causes of viral gastroenteritis and are responsible for most of the cases worldwide. Other viral agents associated with this disease include human noroviruses, Aichi virus 1, enteric human bocavirus, enteric human adenovirus and many other emerging viral agents such as klassivirus, Saffold virus, cosavirus and others. In 2009 the South African government introduced a rotavirus vaccine, RotaRixTM into the expanded programme on immunisation (EPI). More than a 50% decrease in diarrhoea related morbidity and mortality due to rotavirus infections was noted during surveillance studies on the efficacy of the vaccine. However, over 40% of cases of gastroenteritis are of unknown aetiology. The present study aimed to perform a preliminary study to investigate the presence of Aichi virus 1 and enteric human bocaviruses in the Eastern Cape Province by the use of molecular techniques. Furthermore, the study aimed to add to the limited molecular data about enteric adenoviruses in South Africa. Samples used in this study were swab samples collected from Belmont Valley Wastewater Treatment Plant in Grahamstown, South Africa, as well as mussel samples collected from the Swartkops River in Port Elizabeth, South Africa. Both raw sewage and shellfish give a broad idea of what microbes are circulating in the communities. In the present study, twenty swabs and twenty mussel samples were prepared by centrifugation, sonication and filtration. Samples were then subjected to transmission electron microscopy (TEM) analysis, for which the electron micrographs revealed presence of viral particles with diameters ranging from around 20 nm to just over 100 nm. Viral nucleic acids were extracted from 140 μL of the twenty swabs and twenty mussels samples using the QIAamp® Viral RNA Mini Kit, following manufacturer‟s instructions. For detection of Aichi virus 1 from the swab and mussel samples three reverse transcriptase- polymerase chain reaction (RT-PCR) assays using the Verso 1-Step RT-PCR Hot-Start Kit were developed. The first RT-PCR assay targeted amplification of the highly conserved 5′ UTR using published primers. However, despite many amplification attempts no positive results were obtained from both swab and mussel samples. It was only after the addition of DMSO (to a final concentration of 10%) that one swab sample was positive for this assay. In addition, a 2-step RT-PCR was developed using the Maxima H Minus First Strand cDNA Synthesis Kit. By using this 2-step RT-PCR assay, an additional swab sample was positive for the Aichi virus 1 5′ UTR. Using Basic Logarithm Alignment Search Tool (BLAST) analysis these two samples were 98% identical to an Aichi virus isolate from South Korea. The second one-step RT-PCR assay targeted amplification of the 266 bp partial 3CD coding region of Aichi virus 1 using published primers. By using this assay, positive results were obtained from both the swab and mussel samples, which when analysed by BLAST were all 99% identical to various Aichi virus 1 isolates in GenBank. A phylogenetic tree constructed based on this region showed that isolates from the present study clustered with Genotype B isolates in GenBank. The third assay was a semi-nested RT-PCR assay that targeted amplification of the hypervariable VP1 coding region of Aichi virus 1 using a combination of published primers and those designed in the present study. Amplicons which were 472 bp in size were produced from two swab samples. When analysed by BLAST, these two swab samples had percentage identities of 98% to an Aichi virus isolate from South Korea. A phylogenetic tree constructed based on this region showed that isolates from the present study clustered with Genotype B isolates in GenBank. This was consistent with phylogenetic results discussed above which were based on the partial 3CD region. For detection of enteric human bocaviruses from the swab and mussel samples a nested polymerase chain reaction (PCR) assay, using the Ampliqon Taq PCR kit (Ampliqon Bio Reagents and Molecular Diagnostics, Denmark) was developed based on PCR amplification of the 382 bp partial VP1/VP2 coding region using published primers. A total of six swab samples and six mussel samples were analysed for which five swabs and six mussel samples gave positive results. When analysed by BLAST, the swab samples had percentage identities of between 98% and 99% to an enteric human bocavirus 3 strain from China while the mussel samples were all 99% identical to an enteric human bocavirus 2 isolate from Australia. A phylogenetic tree constructed based on this VP1/VP2 region showed that isolates from the present study clustered with human bocavirus 2 and human bocavirus 3 isolates in GenBank for those isolated from swab samples and mussel samples respectively. Lastly, for detection of enteric human adenoviruses from the swab and mussel samples a nested PCR assay, using the Ampliqon Taq PCR kit (Ampliqon Bio Reagents and Molecular Diagnostics, Denmark) was developed. This reaction was based on PCR amplification of the 168 bp partial hexon coding region using published primers for which ten swab samples gave positive results. When analysed by BLAST, the swab samples had percentage identities of between 96% and 99% to enteric human adenoviruses in GenBank. A phylogenetic tree constructed based on the hexon coding region showed that isolates from the present study clustered with subtypes C, D and F which are associated with gastroenteritis worldwide. Despite several amplification attempts no positive results were obtained from mussel samples. The results from the present study show that Aichi virus 1, enteric bocaviruses and enteric adenoviruses are present in the Eastern Cape Province of South Africa. These viruses could possibly be responsible for enteric infections in South Africa. Although only a few samples were analysed, this study is the first to confirm the presence of Aichi virus 1 and enteric bocaviruses in South Africa and provides a platform for further investigation into prevalence and epidemiology of these viruses in the country.
- Full Text:
- Date Issued: 2019
Recruitment of bivalve molluscs with specific emphasis on Mytilus galloprovincialis in the Knysna estuarine embayment, South Africa
- Authors: Radloff, James Victor
- Date: 2019
- Subjects: Mytilus galloprovincialis -- South Africa -- Knysna Lagoon , Introduced aquatic organisms -- South Africa -- Knysna Lagoon , Mexilhao mussel -- South Africa -- Knysna Lagoon , Oysters -- South Africa -- Knysna Lagoon , Mytilidae -- South Africa -- Knysna Lagoon , Bivalves -- South Africa -- Knysna Lagoon
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76733 , vital:30613
- Description: Alien invasive species have the ability to transform or alter environments, often causing severe ecological and/or economic impacts. Marine bioinvasions are occurring globally and are most often facilitated (intentially and accidently) through anthropogenic activities including the building of inter-oceanic canals, shipping and commerce. The Mediterranean mussel, Mytilus galloprovincialis, is a globally successful marine alien invasive species which was first recorded on the west coast of South Africa in the late 1970s and the south coast in 1988. This species is thought to have reached the Knysna Estuary in the early 2000s and has colonised all man-made hard substrata in the embayment of the estuary. Although there are studies on recruitment of M. galloprovincialis on the rocky intertidal coasts of South Africa, there is little information on recruitment of this species in more sheltered estuarine environments. This study aimed to determine recruitment levels of M. galloprovincialis and other bivalves within the Knysna estuarine embayment. To determine monthly recruitment, 10 recruit collectors/pads (plastic pot scourers) were placed at three separate locations within the embayment of the estuary for a week on a monthly basis for 20 months. In addition, recruitment of M. galloprovincialis over spring and neap tides and different lunar phases was also determined at two sites within the Knysna estuarine embayment during the main reproductive season in 2018. The pads were deployed three days before a neap/spring tide and then collected three days after the respective tide. Finally, to look at how rapidly M. galloprovincialis and other macroinvertebrates (when M. galloprovincialis was excluded) would re-colonise free space, 18 plots (15x15 cm), consisting of three treatments including a control (A,B and C), were cleared in M. galloprovincialis mussel beds and then photographed monthly for 12 months. Four bivalve taxa (Mytilus galloprovincialis, Perna perna, Ostreidae, unidentified mytilid) were recorded during the monthly study. Recruitment levels for all bivalves differed significantly (P < 0.001) between months and sites, with peak recruitment occurring from late spring to early autumn (November – March). Mytilus galloprovincialis recruitment levels were greater than other bivalves and were up to 4.5x greater than other taxa. Recruitment also varied between years possibly owing to differences in larval supply and/or environmental factors. Spatial variation in bivalve recruitment was observed throughout the study. The greatest recruitment was at the site (Thesen Island Wharf) closer to the entrance of the embayment. By contrast at the site (Railway Bridge) furthest from the entrance lower recruitment was found. This difference is possibly due to differences in hydrodynamics or other biological and/or environmental factors. A preliminary tidal study found that M. galloprovincialis had significantly higher (P < 0.001) recruitment levels over spring tides than neap tides at Thesen Island Wharf, whereas recruitment at the Railway Bridge on spring and neap tides was not significantly different. In the study undertaken in the reproductive season only, recruitment levels were high over a two week period during both a spring and neap tide, suggesting that factors other than lunar phase and the state of tide are more important in determining the timing and intensity of recruitment. The clearance plots created and photographed over a 12 month period showed that M. galloprovincialis rapidly occupied free space (eight months to virtually cover all free space) by encroachment from the adjacent mussel bed. Limpets and barnacles were only able to colonise cleared space when M. galloprovincialis was excluded, suggesting that the mussel has the ability to outcompete indigenous macrofauna for space. The high recruitment levels of M. galloprovincialis compared to other indigenous bivalves, as well as its ability to occupy space rapidly are traits that must contribute to the success of the invasion of this species within the Knysna estuarine embayment, particulary within Thesen Islands Marina and Thesen Island Wharf.
- Full Text:
- Date Issued: 2019
Reimagining constructions of gender dysphoria: a dual systematic review using analytical psychology’s concept of individuation
- Authors: Couch, Matthew
- Date: 2019
- Subjects: Gender identity disorders , Gender identity , Individuation (Psychology)
- Language: English
- Type: text , Thesis , Masters , MScoSc
- Identifier: http://hdl.handle.net/10962/95184 , vital:31125
- Description: The process of conceptualization has long served to capture and represent our perceptions of the social world. Conceptual categories help to make sense of subjective experiences, and through discursive practices may come to construct conventional frameworks of knowledge. Consequently, frameworks operating as natural and immutable run the risk of ignoring the dynamic and diverse experiences of many individuals. Today, conceptual frameworks for gender identity are found as inadequately representing progressive social views on the existence of gender identities manifesting outside of the prevailing male-female binary. Within this space of conceptual contention, the diagnostic category of gender dysphoria has received considerable inspection and critique. In particular, it has been criticised as fundamentally controversial by classifying issues of identity within a clinical framework and, consequently, as contributing to the pathologization of all gender diverse individuals. Thus, efforts to reconceptualise and reimagine gender dysphoria may be found. In this research the concept of individuation, as understood within a framework of analytical psychology, is discussed as a potential consideration in reimagining the concept of gender dysphoria. An overarching framework of social constructionism was adopted within this research in examining how constructions of conventional knowledge come about through regulatory discursive and performative practices. The theoretical orientation of analytical psychology was used to frame the concept of individuation and its application to gender dysphoria. This perspective consulted queer theory as a further critical orientation toward the construction of gender identity. The chosen methodology took form as a dual systematic review using critical interpretive synthesis (CIS) to construct representative frameworks. Psychological literature on gender dysphoria (review 1) and individuation (review 2) was reviewed and synthesised. Review 1 identified conceptual inferences within the literature and assessed their role toward problematic gender discourse, while review 2 served as a contributory tool to critically assess whether the conceptual space was accommodating of the concept of individuation. Findings in review 1 identified contemporary gender dysphoria literature as reinforcing of problematic gender discourse. The prevailing clinical framework on gender dysphoria and gender nonconformity was iterated through conceptual constructs emphasising an experience of pathological distress or life dissatisfaction. As such, a cyclical pathologization of gender diversity is reconstructed through current representations within the literature. However, it was deduced that there are signs of resistance in the literature to the clinical model which challenge and counter the impact of problematic gender discourse. In review 2, individuation was framed by the literature as an intrapsychic facilitator supporting the integration of all aspects particular to the individual personality so that conscious identity becomes congruent with internal nature. Resultantly, one may experience psychosocial maturation and contribute to collective societal progression. For some, individuation prompts a differentiation from collective expectations in integrating one‘s inherent nature into expressed identity. Thus, gender nonconformity may be viewed as an expression of this differentiation when individuation drives the realization of this feature to be intrinsic and natural for the individual. Individuation was determined as incompatible with the category of gender dysphoria, but of value within the conceptual space where efforts to reimagine gender dysphoria are in place.
- Full Text:
- Date Issued: 2019
Religious pluralism: an analysis of its practice and effect in four historical examples
- Authors: Groves, Samuel Peter
- Date: 2019
- Subjects: Religious pluralism , Christianity and other religions , Freedom of religion -- History , Alexandria (Egypt) -- History , Athens (Greece) -- History , Alexandria (Egypt) -- Religion , Athens (Greece) -- Religion , Eusebius, of Caesarea, Bishop of Caesarea, approximately 260-approximately 340 , Constantine I, Emperor of Rome, -337 , Constantine I, Emperor of Rome, -337 -- Religion , Rome -- History -- Constantine I, the Great, 306-337 , Rome -- Religion , Jews -- Spain -- History -- Expulsion, 1492 , Spain -- History -- Ferdinand and Isabella, 1479-1516 , Spain -- Religion
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/67709 , vital:29132
- Description: Despite the fact that religious freedom is considered a basic human right, provided for in the South African constitution, the practise of religious freedom is often denied in certain countries and discouraged in others. The goal of this thesis is to examine four historical examples in which religious freedom was practised or denied, and the effect this decision had on the countries or people concerned. The first example of Alexander's empire is a positive example of religious liberty. His practise of religious pluralism offered peace to the Greeks and Jews of Alexandria, and it prompted creative and intellectual pursuits that would have been impossible without religious freedom. The second example is of Paul the Apostle's approach to positive religious engagement, as recorded in Acts 17 of the New Testament. Paul models constructive religious debate as he engages with the Athenian philosophers. The third example is of Constantine's pursuit of unity through religious prescription. In his bid for one empire under one God, he created both a divided empire and a divided church. The final example is of the Catholic Monarchs of Spain, who through the persecution of Jews and Muslims, caused the economic collapse of Spain and the division of the church within Spain. This thesis provides historical evidence that religious pluralism benefits humanity and it is my hope that it will encourage religious and political leaders to uphold religious pluralism for the good of society and for the good of religion.
- Full Text:
- Date Issued: 2019
Repatriating Xhosa music recordings archived at the International Library of African Music (ILAM) and reviving interest in traditional Xhosa music among the youth in Grahamstown
- Authors: Madiba, Elijah Moleseng
- Date: 2019
- Subjects: International Library of African Music , Xhosa (African people) -- Music , Sound recordings in ethnomusicology -- South Africa , Ethnomusicology -- South Africa -- Makhanda , Cultural property -- Repatriation -- South Africa -- Makhanda , Rap musicians -- South Africa -- Makhanda
- Language: English
- Type: text , Thesis , Masters , MMus
- Identifier: http://hdl.handle.net/10962/76599 , vital:30611
- Description: This research looks at the feasibility of using repatriation as a tool for the revitalisation of indigenous music within a contemporary South African musical context. Using tracks from the International Library of African Music (ILAM), this investigation presents isiXhosa traditional and indigenous music to a group of musicians from a hip-hop background that would never have had access to this type of music before. The thesis then traces their creative use of the music within their own genres. Speaking to the legacy of the Hugh Tracey collection at ILAM and criticisms that have surfaced, this research also attempts to validate the efforts made by Hugh Tracey in collecting and documenting African music. Themes ranging from understanding the term “tradition” are addressed, as well as other technical terms in the vernacular while also exploring and analysing the results of the repatriation project. Practical issues regarding the sampling of indigenous music were interrogated carefully due to the fact that the complexity of African music was foreign to most of the participants. Their familiarity with the music, or lack thereof, either motivated or ended the musicians’ participation in the research project. An in-depth analysis of the results of the musicians’ interaction with the music is presented where this study finds, at the heart of this research, that the musicians performed as agents who easily took to revitalising the music.
- Full Text:
- Date Issued: 2019
Reproductive isolation mechanisms of two cryptic species of Eccritotarsus (Hemiptera: Miridae), biological control agents of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae)
- Authors: Mnguni, Sandiso
- Date: 2019
- Subjects: Eccritotarsus , Meridae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68133 , vital:29202
- Description: Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), is one of the world’s worst alien invasive plants. It is indigenous to the Amazon basin in South America but has become a problematic alien invasive in other parts of the world. As such, several host-specific biological control agents have been sourced from the native distributions in South America and have been released to control this plant where it has become problematic. Two of these agents include the geographically and reproductively isolated cryptic species of Eccritotarsus (Hemiptera: Miridae). One of these species was collected in the upper reaches of the Amazon River in Peru, while the other was collected over 3500km away from that site, in Florianopolis, southern Brazil. These cryptic species were thought to be a single species until recently, when DNA barcoding indicated that they were likely to be two species, and the species status has now been confirmed by interbreeding experiments and detailed morphological studies. The Brazilian population remains Eccritotarsus catarinensis (Carvalho), while the Peruvian population is now known as Eccritotarsus eichhorniae (Henry). The aim of this project was to investigate the mating behaviour and other behavioural traits of the two species that have resulted in reproductive isolation, and which could have led to speciation. In addition, investigations involving analysis of chemical compound compositions of the two species aimed to determine the extent to which the compounds played a role in the development and maintenance of reproductive isolation. To achieve the aims, behavioural-observation experiments were conducted in the form of no-choice, bi-choice and multi-choice tests in 1:1, 2:1 and 3:1 sex ratio assessments, both within and between species. Chemical compound compositions of E. catarinensis and E. eichhorniae were also assessed using Nuclear Magnetic Resonance (NMR), Solid-phase micro-extraction (SPME) and Gas-Chromatography Mass-Spectrometry (GC-MS) techniques. In no-choice experiments, the highest number of single and multiple copula incidences, and average total copula duration was found within species while copulation between species was much rarer. In bi-choice experiments, E. eichhorniae females and E. catarinensis males only chose to mate with their respective conspecifics, and within species copulations continued to have higher average total copula duration. In multi-choice experiments, the highest number of single and multiple copula incidences and average total copula duration was also found within species. GC-MS analysis suggested that E. catarinensis females and E. eichhorniae males have unique chemical compounds missing in their conspecifics and same sex of the other species. Further analysis suggested that E. catarinensis females and E. eichhorniae males have similar chemical compound compositions, whereas as E. eichhorniae females and E. catarinensis males have similar chemical compound compositions. These results suggest that there are behavioural differences that led to the development and maintenance of prezygotic reproductive isolation mechanisms, and that this is probably driven by pheromones in chemical compound compositions. These two species were geographically isolated in the native range and the populations have diverged to the point that they are now reproductively incompatible and therefore, distinct species. The main driver of the speciation is most likely mate recognition and attraction, as only reproductively important traits such as pheromones, genitalia, the scent glands and antennae have changed, while other traits, including host range and morphology, have remained remarkably stable. This provides evidence that differences in sexual selection in isolated populations may be important drivers of speciation and reproductive isolation in cryptic species.
- Full Text:
- Date Issued: 2019