Exploring Mesofilter Conservation for Sustainable Agricultural Practice
| Casper J. Crous (casperc@exchange.sun.ac.za) |
To formulate a working model, based on mesofilter conservation, for sustainable agricultural production in general, but timber production in particular in highly threatened mistbelt grasslands, KwaZulu-Natal, South Africa. Essentially we want to assess whether certain mesofilters could predict local plant and invertebrate diversity, to sharpen our landscape design process (Ecological Networks), either for new development, or current management improvement.
|
Phylogeography of the generalist Rodent mite Laelaps giganteus, using mitochondrial and nuclear DNA markers: a genetic approach to host-parasite interactions
1,2Adriaan Engelbrecht
 Supervisors: 1Dr. Sonja Matthee and 2Prof. Conrad A. Matthee
1Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
2Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
The relationships between parasites and hosts have often been studied due to the potential impact these may have on the health of domestic animals, wild-life and humans. The generalist parasitic mite, Laelaps giganteus is a widespread southern African parasite, which generally occurs on a wide variety of small mammal species in this region. Morphological descriptive characters could however not determine if multiple lineages are present within L. giganteus. Several studies in southern Africa have suggested that geographically wide spread species are often cryptic species that have developed over time possibly as a result of habitat fragmentation and isolation. This study will aim to record the phylogeographic structure of the mesostigmatid mite, L. giganteus, on Rhabdomys pumilio and R. dilectus in South Africa. The presence of multiple lineages within L. giganteus will be investigated using a combination of mtDNA, nuclear DNA and morphological markers. This will be done following a broad sampling strategy encompassing South Africa and isolated localities in the southern African region. The relative importance of hosts and geographic factors in shaping the phylogeographic pattern will be determined. This study also presents a novel opportunity to investigate the host parasite interaction at three spatial scales in South Africa.
Landscape genetics and conservation planning of South African dwarf chameleons: Anintensive look at a recently radiated clade from KwaZulu-Natal Province
| Jessica Marie da Silva (jessica.m.dasilva@gmail.com) |
The aim of my study is to examine the underlying processes of speciation and morphological variation in a recently radiated clade of dwarf chameleon restricted from the central -to-southern portion of Kwa-Zulu Natal Province, South Africa. Findings from recent Bradypodion phylogenetic and phylogeographic studies have shown this clade to be 'taxonomically problematic' given the observed discordance between morphology and genetics among its species.
The clade is currently comprised of two species: B.melanocephalum (the KwaZulu-Natal dwarf chameleon - formerly known as the Black-headed dwarf chameleon) an open grassland species; and B. thamnobates (the Natal Midlands dwarf chameleon), typically a closed canopy/forest species. However, substantial variation in both morphology and/or habitat throughout the species ranges suggest that ecomorphs and cryptic species may exist within the clade.
This observed discordance might be associated with shifts in vegetation structure, causing different evolutionary processes to act on different lineages. Unravelling the truth behind these complexities is essential before adequate conservation action can be considered and implemented.
To do this I will be using the following techniques:
1) Landscape genetics will examine the fine-scale geographical and genetic differences among chameleons distributed in different vegetation types to determine whether vegetation, as a substrate, influences chameleon differentiation.
2) Morphometric analyses, performance testing and dietary analyses will examine how the chameleons have physically adapted to their differing habitats.
3) Ecological niche modelling will be used to model past, present and future species distributions, along with habitat and climatic changes, to obtain a better understanding of the evolutionary relationships, historical biogeography and the tempo and mode of radiation in this clade.
4) All of the above will be considered together in a prioritization exercise to assess if present day protected areas will be able to maintain this clade's diversity given expected climate scenarios.
|
Comparative phylogeography of the four-striped mouse, Rhabdomys pumilio and its specific parasitic louse, Polyplax arvicanthis
Nina du Toit1*, Sonja Matthee2, Bettine van Vuuren1, Conrad A. Matthee1
 1Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
2Department of Conservation Ecology and Entomology, Stellenbosch University, South Africa
Parasite-host interactions may lead to varying levels of congruence between parasite and host geographic genetic structures, ranging from complete incongruence to instances of strict co-speciation. The level of congruence is usually a reflection of the intimacy of the interaction between the host and parasite species, as determined by life history, ecological and demographic traits. In the current study the phylogeographic structures of the four-striped mouse Rhabdomys pumilio, (Rodentia: Muridae) and its parasitic sucking louse Polyplax arvicanthis (Phthiraptera: Anoplura) will be determined and compared for potential congruence by utilizing mitochondrial and nuclear DNA sequences. Polyplax arvicanthis possess several traits (such as host specificity, no free living phase or intermediate host as well as high levels of prevalence and abundance) that predict congruent structure with the host.
In vitro culturing of entomopathogenic nematode Heterorhabditis zealandica
| Tiarin Ferreira (tferreira@sun.ac.za) |
In Europe the first steps towards outdoor commercial application have been taken using entomopathogenic nematodes. Various nematode formulations against a wide range of insect pests are commercially available. For the quantities needed for field application against pest insects, in vitro liquid culturing methods need to be developed. An endemic isolate of H. zealandica has been selected as an effective biological control agent against a wide range of key pests associated with deciduous fruit and citrus. To culture H. zealandica, the associated bacteria has to be characterized, sub-cultured and stored in a viable state. The symbiotic bacteria namely Photorhabdus and Xenorhabdus have been researched and analysed and found containing considerable diversity among the symbionts. They thrive in entomopathogenic nematodes that belong to the genera, Steinernema and Heterorhabditis (Koppenhöfer, 2007). These bacteria colonize the intestine of infective juvenile nematodes which persist in the soil and search for suitable insect hosts. Upon invasion through natural body openings, the infective juveniles migrate into the host haemolymph to release the symbiotic bacteria. The bacteria multiply, killing the insect and converting the cadaver into a food source for nematode growth and reproduction. These nematodes have the potential to be biological control organisms. For biocontrol purposes nematodes are produced in industry-scale bioreactors. Research data on commercial mass production of entomopathogenic nematodes is mostly industry based and therefore not freely available. Entomopathogenic nematodes are not commercially available in South Africa yet. For my study genomic and phylogenetic characterization and phenotypic characterization are conducted with the symbiotic bacteria Xenorhabdus and Photorhabdus. Liquid media are evaluated for H. zealandica and the development of the nematodes in the liquid are investigated.
|
The invasive ant, Pheidole megacephala, on a tropical island: Distribution, impact and control
| René Gaigher (reneg@sun.ac.za) |
Invasions by alien ants have affected many continental and island ecosystems throughout the world, often with severe consequences to native biodiversity. Introduced ants have the capacity to reach unusually high densities in their introduced habitats, resulting in major impacts on native biota. In some regions, catastrophic shifts in ecosystem function have been documented, caused by ant invasions that have altered native interaction webs. Oceanic islands, with their simple food webs and low functional redundancy, are particularly vulnerable to invasion. Yet, because of their simplicity and isolation, they also serve as model systems for understanding the effects of invasions on ecosystem structure and function. For my PhD, I examine the community interactions of the invasive ant, Pheidole megacephala, on Cousine Island, a small tropical island in the Seychelles. I focus on the community-wide impacts of P. megacephala, with emphasis on direct effects on the invertebrate fauna and indirect effects on the ecosystem via the ant-homopteran mutualism. During the study, large-scale manipulation of the ant’s population levels and monitoring of species that interact closely with the ant will enable an assessment of the response of the ecosystem to P. megacephala control. Such manipulative field experiments are ideal opportunities to elucidate the mechanisms driving the impacts of alien species. It will also demonstrate the consequences of alien removal, which can be complex and unpredictable. In this case, it also serves as a detailed evaluation of a potential control method for P. megacephala, which will support management decisions of the species on the island and in other natural ecosystems.
|
Acoustic Profiling
Paul B.C. Grant - Postgraduate Representative (pbcgrant@sun.ac.za)
Building resilience to climate change impacts in working landscapes
Rapid and global change in climate is expected to have adverse impacts on human health, ecosystem and socioeconomic systems at local, regional and global scales. Of particular concern is the interaction of climate change with existing anthropogenic stressors, which may push a system beyond its ability to function properly. In my study I investigate the cause and effect of regime changes in a working landscape using the Eden District situated in the Western Cape Province, South Africa as a study site. When a system’s resilience is compromised, it is more vulnerable to shift to an alternative and undesirable state. Synergistic effects of interacting drivers along with recurrent extreme events may weaken system resilience and trigger a regime shift. In order to strengthen the evidence base and methodologies in this relatively new field, causal loop diagrams will be used to investigate common feedback mechanisms, system behaviour and variables acting upon drivers of change within the district. By identifying key drivers responsible for weakening feedback mechanism in a particular regime, one can begin identifying higher- leverage actions to intervene in good time and prevent the system from tipping over into an alternate state. The role that ecosystem based adaptation can play in climate change reduction and enhancing the resilience of water related systems and services in the district will be explored as well.
|
Evaluating social-ecological aspects of edge effects and land use conflicts at the borders of Etosha National Park, Namibia
Buffer zones are created to overcome artificial boundaries between people and nature so as to achieve environmental protection while simultaneously improving the social-economic conditions of communities living in and adjacent to protected areas. In Namibia, the ‘Etosha buffer zone project’ was developed to facilitate current efforts of connecting the Etosha National Park (ENP) and the Skeleton Coast National Park (Etosha Skeleton Coast Link) in an attempt to re-open traditional migratory routes of wildlife species and to link ENP with the transnational protected area network of southern Africa. The overall goal of the ‘Etosha buffer zone project’ is to apply the buffer zone concept to the ENP, consequently minimising edge effects and land use contrasts and enhancing the adaptability of the ecosystem. The applicability of the buffer zone concept, however, needs to be tested and site-specific criteria need to be defined. The definition of the objectives of a specific buffer zone is highly context specific, thus the ecological system and the aspects defining the system first need to be understood. Furthermore, effective conservation in protected area buffer zones will only succeed if local communities and land users participate in the management of such areas. These stakeholders need to be defined and prioritised for involvement in decisions about the various aspects of the system. The PhD forms part of an umbrella project aimed at successfully implementing the ‘Etosha buffer zone project’ and will contribute the following:
• Describe social-ecological conditions of selected key areas under different forms of land use (private and state owned farms, communal areas and community conservancies);
• Assess edge effects and land use conflicts using social-ecological approaches; and
• Evaluate the social-ecological potential of the selected key areas.
|
Tree health in natural, invaded and restored riparian landscapes: the role of pest and pathogens
| Malebajoa Anicia Maoela (maoela@sun.ac.za) |
Riparian ecosystems represent an essential component of biodiversity and are ecologically and socio-economically significant habitats. However, studies that assess the success of riparian restoration projects seldom focus on tree health of riparian tree communities. This under-presentation of riparian tree health is largely a result of lack of knowledge of diversity and abundance of damage and disease-causing agents like fungi and insects. Insects and fungi are the integral parts of riparian ecosystems, but under conditions that lead to tree stress, they may produce undesirable effects. The overall goal of this study involves identification of ecological and morphological effects that fungal pathogens and insects pests have on woody tree species (native and invasive) in riparian systems. Emphasis is placed on differences in the diversity and abundance of these organisms at different sites: a) Acacia invaded, b) natural and c) sites cleared of invasive species. In addition, quantification of the effects of damage caused by insects and fungi on photosynthesis of native and selected alien trees, as well as shifts in both native and alien-invasive tree functional traits will be carried out. With these approaches, I hope to understand what riparian zone factors (e.g. host population, microclimate and disturbance regimes), diversity and abundance of fungi and insects respond to. The response of tree physiological processes and tree effect traits to fungal pathogens and insect damage at sites under varying stress conditions will also be understood. Results will allow suggestion of an envelope of possible management practices necessary to control the identified pests and fungi.
|
Thermal tolerance of Ceratitis rosa and Ceratitis capitata (Diptera: Tephritidae) in South Africa: implications for population dynamics and pest management
My research interests are in the ecology and management of economic agricultural pests with emphasis on Integrated Pest Management (IPM). Am currently working on the thermotolerance of fruit flies (Ceratitis rosa and Ceratitis capitata) (Diptera: Tephritidae). The Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) and the Natal fruit fly Ceratitis rosa Karsch are deleterious fruit pests that hinder the economic production of deciduous and citrus crops in South Africa. Both species are multivoltine international quarantine pests that are highly polyphagous, invasive and widely distributed in Africa. However, current work aimed at predicting potential Ceratitis rosa and capitata distribution in the Western Cape region, South Africa requires thermotolerance data in order to predict the geographic distribution of these flies. Survival of extreme temperatures is also a critical aspect of population dynamics for both species. This project aims to investigate several aspects of C. rosa and C. capitata thermal biology. First, geographic variation of thermotolerance, indicative of local climatic adaptation, among fruit fly populations is currently unknown. Second, overwintering strategy (i.e. where and how flies survive during the winter), is currently unknown for local fruit fly populations and is an important source of reinfestation for Ceratitis species each spring. Third, factors influencing temperature tolerance within C. capitata and C. rosa populations (e.g. age, gender, feeding/reproductive status) have not been well investigated. Furthermore, it is also significant to consider how the thermal environment affects survival and how it might limit the behavioral activity of Ceratitis species. Few studies have considered the physiological responses to temperature treatment (i.e. phenotypic plasticity) of Ceratitis species. Phenotypic plasticity is a major mechanism used by arthropods to cope with temperature fluctuations both daily and seasonally and also upon introduction to novel environments. Finally, the success of the Sterile Insect Technique (SIT) programs in the control of fruit flies may be improved by pre-conditioning laboratory-reared flies prior to release in the wild to enhance field thermotolerance, performance and survival. Consequently, this project aims to explore 1) how temperature might influence the population dynamics through mortality, and hence, overwintering physiology and geographic distribution of C. rosa and C. capitata and 2) how fly thermotolerance might be manipulated for the successful control of these species. The results of this project may help provide an empirical framework for understanding the thermal factors limiting geographic distribution of C. rosa and C. capitata. These results may also be useful to sterile insect technique programmes, post-harvest control and sterilization techniques, prediction of the potential invasiveness of the two species at various timescales, and could also be valuable to pest risk analyses.
|
The effect of vegetation type on the species composition and geographical distribution of economically important ticks on cattle in the Eastern Cape Province
Nkululeko Nyangiwe (nyangiwenku@yahoo.com)
Supervisor: Dr S. Matthee
 Tick infestations and tick-borne pathogens are considered as a major problem in cattle production by causing great economic losses and transmit a wider variety of pathogenic agents compared to other group of arthropods. Tick species can be divided in one-, two- and three host ticks with free-living stages occurring in the surrounding vegetation. The project is conducted at two scales. At the local scale the study is conducted on twenty communal farms during the peak activity season ( October-February) for parasitic and non-parasitic ticks in the south-western region of the Eastern Cape Province (ECP). Four veld types are included namely; 1) Coastal forest and Thornveld 2) Eastern Province Thornveld 3) Valley Bushveld 4) Dohne Sourveld. A step point method (grass sward) and belt transect technique (woody layer) is used to assess the vegetation structure (cover, height and plant species richness) in each of the vegetation types. To date, few studies have research the effect of vegetation structure (percentage cover, vegetation height and plant species composition) on tick abundance and species composition. It is to be expected that variation in micro-habitat conditions will have varying effects on the survival of free-living tick stages with potential knock-on effects on the species composition and abundance on the vegetation and host. At a larger regional scale, ticks are obtained from willing farmers, irrespective of farming system in the rest of the ECP, in the Western Cape Province, Northern Cape, Free Sate and any other province where there is currently a lack of or out-dated information regarding the distribution of the alien invasive Asiatic blue tick, Rhipicephalus (Boophilus) microplus. In addition, this part of the study is extended to Namibia as several of the dairy farmers in Namibia import cattle from the ECP. The objectives of this study are to determine the effect of vegetation type on the tick species composition and diversity on cattle and in the environment (i.e. on the vegetation) on communal farms in the south-western region of the Eastern Cape Province. Secondly, to establish the effect of vegetation changes (e.g. reduced plant cover and plant diversity) associated with over-grazing on the tick species composition on cattle and in the environment. Thirdly, to obtain baseline data on the perceptions of cattle farmers with regard to ticks, tick-borne diseases and the management practices that are currently being used on communal and commercial farms in the Eastern Cape Province. Fourthly, to record the geographic distribution of alien invasive Asiatic blue tick, R. (Bo) microplus , and a related endemic species Rhipicephalus (Boophilus) decolaratus in the south-western part of the Eastern Cape Province and the surrounding provinces in South Africa. To our knowledge no reports have been made on the displacement of R. (B.) decoloratus by R. (B.) microplus in the south-western regions of this province and mapping the distributions of the two ticks in this region is thus a priority.
Water availability and the occurrence of lateral zones in South African riparian vegetation
| Karl Reinecke |
| Supervisor: Prof. K. J. Esler |
Karl has been working in the field of Freshwater Ecology since 2000. His main interests are river restoration and the nature of riparian vegetation. He has experience in drivers of riverine ecosystems, aspects of physical degradation of rivers and mitigation thereof, impacts of riparian plant invaders, drivers of riparian community structure. He is currently busy with his PhD in riparian botany that is focused on quantifying the links between river flow and the life histories of some species commonly found in riparian scrub communities of Western Cape Rivers. His research will inform water resource developments by providing tools for Environmental Flow studies and river Habitat Integrity assessments.
|
Navigating ecosystem services: bridging the gap between science and implementation, a case study in Eden
The purpose of my research is to enhance understanding of the gap/tension that exists between the science and implementation of ecosystem service research and explore and reflect on possible solutions for bridging this divide. Using a case study in the Eden District Municipality my research serves to contribute to both academic and pragmatic debates on how to improve the integration and utility of scientific information for enhanced governance and resilience of socio-ecological systems.
|
| |
Rodents (Rodentia) and insectivores (Insectivora) are amongst the most numerous of all mammals and form part of nearly all terrestrial communities. Their large numbers and short generation intervals contribute significantly to the energy flow in nature and they are important in maintaining ecosystems. These small mammal taxa make an important contribution to South Africa’s biodiversity. In addition, several rodent species, including Rhabdomys pumilio have adapted well to anthropogenic activities, often being found in close contact to humans and domestic animals, and can thus pose a diseases risk. They have long been identified as integral to the domestic cycle of the zoonotic helminth Trichinella spiralis, and they can act as reservoir hosts for diseases, such as rabies, toxoplasmosis, plague and other helminths. In addition parasites have a significant impact on host ecology and may directly influence host population fluctuation. Knowledge of the helminth communities of rodents and insectivores, their composition and processes that govern their specific patterns are scant within the entire African continent. The majority of studies have been conducted in the Palaearctic region. The rodent Rhabdomys pumilio is widely distributed across the central and western parts of South Africa while R. delectus seem to occur in the mexic eastern parts of the country. At present limited data exists on the helminth diversity of R. pumilio that occur along the far western part of the country. It is uncertain if these helminth assemblages persist though out South Africa. Climate and vegetation play an important role in the survival and transmission of helminth parasites and it is expected that there will be a positive relationship between precipitation and helminth diversity. Cestodes (flat worms) and nematodes (round worms) differ in terms of life history. Cestodes generally require an intermediate host (e.g. insect) as part of their life cycle. Insect eating hosts would harbour a larger number of cestode species compared to strictly plant eating host species. Small mammal assemblages often comprise of plant and insect-eating species. We would expect that host diet will play an important role in the helminth species assemblage, however, phylogenetic relatedness may also influence the pattern as closely related host species should have more similar helminth assemblages compared to more distantly related species. The overall objectives of this study is to determine the geographic distribution of helminths of Rhabdomys and to analyse the structure of helminth assemblages of selected species of rodents, including Rhabdomys, and insectivores that co-occur in various vegetation zones in South Africa, using species composition, richness, prevalence and abundance as parasitological descriptors. 
Fleas (Siphonaptera) are obligate ectoparasites of domestic and wild animals. They have a global distribution and occur mostly on mammals and birds, but have been accidently found on reptiles. Around three quarters of all fleas occur on rodent hosts. In addition, fleas can act as vectors of many pathogens that cause disease in wild- and domestic animals and humans. As is the case with many parasite taxa, research to date is heavily biased towards species associated with the veterinary and medical fields and therefore of economic importance. Relatively few studies have been undertaken to investigate flea-rodent host ecology. Most of the studies in Africa, including South Africa, have focused on fleas and the incidence of plague. Subsequently a few descriptive studies were conducted on fleas associated with scrub hare and small carnivores. However, to date very few quantitative studies have been conducted on the diversity and macro-ecological patterns of fleas that are associated with natural occurring wildlife in South Africa. 
Matt’s research primarily focuses on how meaningful nature experiences and profound encounters with wildlife may influence one’s connectedness with nature. Using both qualitative and quantitative methods, the study is investigating individual’s perceptions and shared stories in order to determine key characteristics, context and essence of these lived experiences. The research, based in the Baviaanskloof Mega-Reserve, is also exploring how alien invasive species (mainly the introduced Acacia sp.) may impact upon ones’ direct experience of nature. A final objective is to reflect on how insights and implications from this research may inform tertiary education curricula and community-based practice to help cultivate a lifelong conservation ethic.
