An evaluation of southern Africa's elephant sub-populations as a metapopulation

Elephant management traditionally centers on reducing ecological impact and human-elephant conflict by controlling numbers. However, such an approach only deals with symptoms, and ignores the causes of the problem. Planning for cases when a species is a nuisance in some areas, but threatened in others, could benefit from the application of metapopulation theory. The theory offers a framework that is elegant, and have ecological as well as political appeal. Applying classic metapopulation theory to long-lived species that are widely distributed in stochastic environments where they can resist extinctions is problematic. However, empirical evidence for metapopulation structure may exist when applying more lenient criteria. I examined the literature for empirical support of classic criteria set by Hanski (1999) and for a more lenient sub-set of criteria proposed by Elmhagen&Angerbjörn (2001) for specifically mammals. I propose that for small mammals (≤5kg) the full complement of classic criteria must be applied to yield perspectives on population regulation and conservation. However, for large (>100kg) and medium sized (>5≤100kg) mammals only habitat discreteness, potential of demographic asynchrony and the likelihood of dispersal among sub-populations must be evaluated. Metapopulation theory could then be useful when constructing conservation plans that ensure the persistence of a species and contribute to forces that stabilize populations regionally. I evaluated the applicability of metapopulation theory to southern Africa’s elephant sub-populations. I identified 51 discrete administrative sub-populations that occurred in six conservation clusters. Population growth rates varied across space and time within and among conservation clusters. Some sub-populations and conservation clusters increased or decreased while others remained stable. Therefore, elephant populations in southern Africa were in demographic asynchrony, both on a local and regional scale. I also suggest that dispersal may occur among sub-populations within clusters. Consequently, the regional population is stabilized by emigration to, or immigration from neighboring sub-populations as a result of demographic asynchrony across an ecological gradient. Elephant populations across southern Africa thus adhered to one and could possibly adhere to all metapopulation criteria. Observed changes in elephant numbers could also be the result of survey error. To gain an understanding of how survey error could affect estimates, I used dung counts and measurements to estimate population size and construct an age structure for the elephants living in the Maputo Elephant Reserve in Mozambique. I suggest that dung surveys can yield population estimates with known precision and can be used in monitoring programmes aimed at assessing population trends - despite the fact that it can be affected by observer bias. In this thesis I show that metapopulation theory provides the opportunity of applying a spatio-temporal approach to elephant conservation that is not obsessed with numbers. When implementing metapopulation theory, management no longer have to centre on elephants, but can focus on the landscape as a spatially and temporally dynamic area. Local fluctuations in elephant numbers could be construed within a regional context, rather than implementing management strategies on a local scale. Such an approach will focus on the causes rather than the symptoms of the elephant problem and may contribute to the persistence of elephants as well as other components of southern African biodiversity. AFRIKAANS : Die ekologiese impak van olifante en konflik tussen mense en olifante word tradisioneel hanteer deur olifant getalle te beheer. Ongelukkig los so ʼn benadering net die simptome en nie die oorsaak van die problem op nie. Gevalle waar ʼn spesie ʼn problem is in sommige areas maar bedreig is in ander, kan baat vind by die toepasing van die metabevolkings teorie. Die teorie bied ʼn elegante raamwerk wat op ekologiese en politieke gebiede aanklank vind. Die toepasing van die klassieke metabevolkings teorie op lang lewende spesies wat wyd versprei voorkom in stochastiese omgewings waar hulle weerstand kan bied teen uitsterwings skep egter probleme. Emperiese bewyse vir ʼn metabevolkings struktuur kan egter voorkom waneer meer gematigde kriteria ondersoek word. Ek het die literatuur ondersoek vir emperiese ondersteuning vir die klassieke kriteria wat Hanski (1999) voorgestel het, asook vir ʼn meer gematigte sub-groep van kriteria wat deur Elmhagen&Angerbjörn (2001) vir spesifiek soogdiere voorgestel is. Ek stel voor dat die klassieke kriteria aangewend kan word om bevolkings van klein soogdiere (5≤kg) te reguleer, beter te kan verstaan en dan te bewaar. Vir groot (>100kg) en medium groot (>5≤100kg) soogdiere kan die metabevolkings teorie net gebruik word as die bestaan van aparte habitate, demografiese asinkronie en die potensiaal van verstrooing tussen tussen subbevolkings bewys kan word. Die metabevolkings toerie kan dan gebruik word om bewarings inisiatiewe in te stel wat spesies in staat sal stel om voort te bestaan en oor die streek te stabiliseer. Ek het die toepasbaarheid van die metabevolkings teorie vir suidelike Afrika se olifant sub-bevolkings ondersoek. Ek het 51 aparte administratiewe sub-bevolkings geidentifiseer wat in ses ‘bewaringsklosse’ voorkom. Bevolkings groeitempos het binne in en tussen bewaringsklosse gewissel. Sommige het of toegeneem of afgeneem terwyl ander stabiel gebly het. Olifant sub-bevolkings in Suider Afrika was dus in demografiese asinkronie, op ʼn lokale sowel as op ʼn streeks vlak. Ek het ook voorgestel dat verstrooing kan voorkom tussen sub-bevolkings binne in bewarings klosse. Die olifant bevolking van die streek word dus deur emigrasie na, of immigrasie van naburige sub-bevolkings as gevolg van demografiese asinkronie oor ʼn ekologiese gradient gestabiliseer. Olifant bevolkings in Suider Afrika het dus voldoen aan een, en kan potensieel voldoen aan alle metabevolkings kriteria. Opmerklike veranderinge in olifant getalle kan ook wees as gevolg van foute wat tydens tellings gemaak word. Om beter te verstaan hoe sulke foute bevolking skattings affekteer, het ek olifant mis tellings en metings gebruik om ʼn bevolking skatting en ouderdomsstruktuur vir olifante in die Maputo Olifant Reservaat in Mosambiek saam te stel. Ek stel voor dat mis opnames bevolking skattings kan lewer wat bekende presiesie het en dat dit gebruik kan word in moniterings programme wat neigings in olifiant bevolkings ondersoek - alhoewel sulke skattings beinvloed kan word deur die vooroordeel van waarnemers. In hierdie tesis toon ek aan dat die metabevolkings teorie ʼn geleentheid skep vir ʼn ruimtelike-tydelike benadering in olifant bewaring wat nie net op getalle fokus nie. Wanneer die metabevolkings teorie toegepas word, kan bestuur op die landskap as ʼn ruimtelike en tydsgebonde dinamiese area fokus, in plaas van net op olifant getalle. Lokale wisselings in olifant getalle kan binne in ʼn streek konteks geinterpreteer word, eerder as om bestuurs inisiatiewe net op ʼn lokale vlak in te stel. So ʼn benadering sal fokus op die oorsprong in plaas van die simptome van die olifant problem en mag bydra tot die voorbestaan van nie net olifante nie, maar ook tot die biologiese diversiteit van Suider Afrika. CopyrightDissertation (MSc)--University of Pretoria, 2010.Zoology and Entomologyunrestricte

Multi-scale sampling boosts inferences from beta diversity patterns in coastal forests of South Africa

AIM : We used a hierarchical fractal-based sampling design to test how sampling scale influences i) beta diversity and ii) inferences on the modelled contribution of niche- versus dispersal-based assembly processes in structuring tree and bird assemblages. Location Coastal forest fragments, South Africa METHODS : We surveyed 103 tree and 267 bird points within eight forest fragments and partitioned beta diversity (βsor) into its turnover (βsim) and nestedness (βnes) components. We evaluated how sampling at fine, intermediate and coarse scales influenced beta diversity components and compared how tree and bird beta diversity respond to sampling grain variation. We then explored the relative contributions of niche- and dispersal based assembly processes in explaining spatial turnover as a function of sampling grain and/or study taxon by using multiple regression modelling on distance matrices and variance partitioning. RESULTS : Beta diversity (βsor) of trees and birds was mainly explained by spatial turnover (βsim) at all sampling scales. For both taxonomic groups, βsor and βsim decreased as sampling scale increased. Beta diversity differed among trees and birds at fine, but not at coarse sampling scales. Dispersalbased assembly processes were the best predictors of community assembly at fine scales, whereas niche-based assembly processes were the best predictors at coarse scales. Most of the variation in tree community composition was, however, explained at fine scales (by dispersal-based assembly processes), while most of the variation in bird community composition was explained at coarse scales (by niche-based assembly processes). MAIN CONCLUSIONS : Our study shows that inferences from beta diversity are scale dependent. By matching the grain of the data with the grain at which predictor variables and associated processes are likely to operate, multi-scale sampling approaches can improve biodiversity conservation and should be part of incentives directed at ecological sensible conservation plans.National Research Foundation, South African Department of Trade and Industry and Richards Bay Minerals.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2699hb201

The response of bird feeding guilds to forest fragmentation reveals conservation strategies for a critically endangered African eco-region

South African coastal forests form part of two critically endangered eco-regions and harbor an extinction debt. Remainingfragments are small, isolated, and embedded within a range of human land-use types. In this study, we ask: how should we investconservation resources if we want to restore this landscape and prevent predicted extinctions? To answer this question, we use pathanalyses to determine the direct and indirect effects of forest area, forest connectivity, and matrix land-use types on species richnesswithin five bird feeding guilds. We found that forest connectivity had a significant direct effect on insectivores—fragments thatwere more connected had more species of insectivores than those that were isolated. Moreover, forest area had a significant indi-rect effect on insectivores that was mediated through tree species richness. Larg er fragments had more species of trees, which ledto more species of insectivores. Fragment area, connectivity, matrix land-use type, and tree species richness had no significanteffects on the species richness of frugivores, nectarivores, granivores, or generalist feeders. To conserve insectivores in coastal for-ests, conservation efforts should focus on maximizing fragment connectivity across the landscape, but also protect the tree commu-nity within fragments from degradation. This can be achieved by including matrix habitats that adjoin forest fragments withinforest conservation and restoration plans. Natural matrix habitats can increase connectivity, provide supplementary resources, bufferfragments from degradation, and could play an important role in safeguarding diversity and preventing extinctions in this threatenedhuman-modified landscape.Grants from the National Research Foundation, the University of Pretoria, the South African Department of Trade and Industry and Richards Bay Minerals to RVA enabled the study. PO was supported by an Innovation post-doctoral fellowship from the National Research Foundation (Grant No: 88173) and an Ecologist in Africa grant from the British Ecological Society (Grant No: 5169-6211).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1744-74292018-03-31hb2017Zoology and Entomolog

Determinants of canopy gap characteristics in rehabilitating coastal dune forests

QUESTIONS : What drives canopy gap formation in regenerating coastal dune forest? Does canopy gap size frequency distribution differ between new and old‐growth forests? Can canopy gaps divert regenerating trajectories? LOCATION : Rehabilitating coastal dune forest, KwaZulu‐Natal, South Africa. METHODS : We mapped canopy gaps in regenerating dune forest patches of varying age, which develop after seeding of the pioneer Vachellia kosiensis, and a reference forest by means of unsupervised classification of multi‐spectral satellite images. We tested if gap formation can be explained by abiotic (exposure to winds) and/or biotic (tree density at early stages) variables. We calculated the scaling exponent of a power‐law model to quantify if gap size frequency differed between new and old‐growth forests. Finally, we measured canopy openness, tree height and number of stems to validate canopy gap classification and assess the consequences of canopy gaps on regenerating trajectories. RESULTS : Exposure to winds and tree density at early stages were both significant predictors of gap presence. Gaps were more likely to be present along dune ridges and areas with low tree density than valleys and areas with high tree density at early stages. Large gaps were common in both new and old‐growth forests. The scaling exponent was positively related to regeneration age, indicating a reduction in gap size as the forest aged. Areas with open canopies had shorter individual trees that were more likely to be multi‐stemmed than areas with closed canopies. CONCLUSION : Canopy gaps are an important component of new and old‐growth coastal dune forests dynamics. Although gaps are filled during forest development, changes in individual life‐history strategies and morphology may alter regeneration trajectories. However, because their effect is partly controlled by the exposure to wind and tree density at early stages, it can also be manipulated by management to ensure nucleation, which could accelerate forest recovery.Appendix S1. Overview of the study area.Appendix S2. Mixture distribution of canopy openness.Appendix S3. NDVI values at 10 years since rehabilitation.V. Rolo and P. Olivier were supported by a post‐doctoral grant from the NRF of South Africa. RJvA was supported by the National Research Foundation (NRF), the Technology and Human Resources for Industry Programme (THRIP) and Richards Bay Minerals.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1654-109X2019-07-01hj2018Zoology and Entomolog

Tree and bird functional groups as indicators of recovery of regenerating subtropical coastal dune forests

Functional diversity indicators are increasingly used to monitor forest function recovery because they connect biodiversity to ecosystem functions. However, identifying which functions deviate from a reference forest has not received much attention, despite its potential to inform restoration interventions. In this study, we used functional groups to assess the recovery of ecosystem functions in regenerating coastal dune forests. We surveyed birds and trees in forest of different ages and a reference old-growth forest in KwaZulu-Natal, South Africa. We classified species into functional groups for each taxa based on functional traits or a priori defined categories (i.e. guilds) and quantified the number of species within functional groups as a proxy of function stability. Bird species density followed an asymptotic trajectory, reaching old-growth forest values after 25 years. Insectivores and granivores showed saturating trajectories, whereas small frugivores and generalists increased linearly. With the exception of large frugivores, relative abundances of bird functional groups progressed towards old-growth forest values as the forest aged. Tree species density increased linearly with forest age. In contrast to old-growth forests, large-canopy trees and understory shrubs were under-represented, while mid-canopy trees dominated regenerating forests. Our result suggests that most bird, but not tree, functions may have been restored. The trend in large frugivore numbers may warrant further investigation, as their low numbers may have hampered the recovery of tree functions. We conclude that functional group trajectories can track functions that deviate from a benchmark, and may therefore direct adaptive actions to recover the stability of regenerating forest.R.vA. was supported by RBM, the National Research Foundation (NRF) and the Technology and Human Resources for Industry Programme (THRIP). V.R. and P.I.O. received postdoctoral grants from the NRF of South Africa.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1526-100X2018-09-30hj2017Zoology and Entomolog

Pattern or process? Evaluating the peninsula effect as a determinant of species richness in coastal dune forests

The peninsula effect predicts that the number of species should decline from the base of a peninsula to the tip. However, evidence for the peninsula effect is ambiguous, as different analytical methods, study taxa, and variations in local habitat or regional climatic conditions influence conclusions on its presence. We address this uncertainty by using two analytical methods to investigate the peninsula effect in three taxa that occupy different trophic levels: trees, millipedes, and birds. We surveyed 81 tree quadrants, 102 millipede transects, and 152 bird points within 150 km of coastal dune forest that resemble a habitat peninsula along the northeast coast of South Africa. We then used spatial (trend surface analyses) and nonspatial regressions (generalized linear mixed models) to test for the presence of the peninsula effect in each of the three taxa. We also used linear mixed models to test if climate (temperature and precipitation) and/or local habitat conditions (water availability associated with topography and landscape structural variables) could explain gradients in species richness. Non-spatial models suggest that the peninsula effect was present in all three taxa. However, spatial models indicated that only bird species richness declined from the peninsula base to the peninsula tip. Millipede species richness increased near the centre of the peninsula, while tree species richness increased near the tip. Local habitat conditions explained species richness patterns of birds and trees, but not of millipedes, regardless of model type. Our study highlights the idiosyncrasies associated with the peninsula effectÐconclusions on the presence of the peninsula effect depend on the analytical methods used and the taxon studied. The peninsula effect might therefore be better suited to describe a species richness pattern where the number of species decline from a broader habitat base to a narrow tip, rather than a process that drives species richness.S1 Dataset. This file contains the data from the article ªPattern or process? Evaluating the peninsula effect as a determinant of species richness in coastal dune forestsº by Pieter I. Olivier, Victor Rolo, and Rudi J. van Aarde.Richards Bay Minerals (RBM), the Department of Trade and Industry's Technology and Human Resources for Industry Program (THRIP) and the National Research Foundation provided financial and logistical support for this study. Pieter Olivier and Victor Rolo were supported by post-doctoral fellowships from the National Research Foundation (Grant no's: 88173 and 88365).http://www.plosone.orgam2017Zoology and Entomolog

Seeded pioneer die-offs reduce the functional trait space of new-growth coastal dune forests

The planting or seeding of pioneer species to promote restoration apparently contributes little to the establishment of late-successional species, despite the common assumption that they facilitate forest regeneration.We evaluate the consequences of planting pioneers for coastal dune restoration by measuring plant traits (specific leaf area, wood density, δ13C and maximum plant height), species composition and canopy openness in three rehabilitating forests of different ages, where a pioneer species (Acacia karroo) was seeded, and one undisturbed old-growth forest.We surveyed woody species composition in 2010 and in 2015 to assess how changes in A. karroo influences community structure of rehabilitating forest. Our results showed that the number of adult individuals of A. karroo decreased progressively with forest age, indicating that the demise of individuals of A. karroo opens canopy gaps in rehabilitating sites. This accorded with a significantly higher variation of canopy openness levels in the oldest rehabilitating site. Rehabilitating sites tended to progress towards a reduced trait space as they aged, contrasting with the old-growth forest that showed an expanded trait space. Communities located at high levels of canopy openness were dominated by species with lower values of specific leaf area and wood density, indicative of acclimation to high light conditions and fast-growing strategies. Our results suggest that changes in light availability due to canopy gap formation, can act as an environmental filter which may deflect forest regeneration trajectories. We show that coupling a trait-based approach with environmental measurements can give insight in regeneration trajectories of rehabilitating sites and, therefore, better inform restoration practices. Preventing the formation of large canopy gaps in restoration programs using pioneers as a regeneration pathway may facilitate the natural recovery of degraded forest.Richards Bay Minerals, National Research Foundation (NRF) and the Technology and Human Resources for Industry Programme (THRIP).http://www.elsevier.com/locate/foreco2017-10-31hb2016Zoology and Entomolog

Functional diversity mediates contrasting direct and indirect effects of fragmentation on below- and above-ground carbon stocks of coastal dune forests

Changes in structure and functioning of tree communities in response to forest fragmentation may alter tropical forest’s capacity to store carbon and regulate climate. However, evidence for indirect effects of forest fragmentation on above – and belowground carbon pools through changes in forest biodiversity is scarce. Here we focus on understanding the relative importance of taxonomic and functional diversity and tree cover to explain above- and below-ground carbon stocks in coastal dune forest fragments. We surveyed tree species composition and structure in six coastal forest patches varying in size from 215 to 13350 ha, in Kwa-Zulu Natal, South Africa. For each fragment, we estimated carbon stocks of two pools, aboveground biomass (AGC) and soil organic carbon (SOC). We used structural equation models to test if and to what extent the effects of forest fragmentation on AGC and SOC were mediated by tree cover and taxonomic and functional diversity. Our results showed that forest fragmentation directly reduced AGC, but increased SOC. In contrast, forest fragmentation indirectly, through decreasing functional diversity, increased AGC, but decreased SOC. Small patches therefore had few tree species that were functional similar and had high AGC, but low SOC, which led to a negative relationship between species richness and AGC. Tree cover was not affected by fragmentation, and had a direct positive effect on AGC but not on SOC. Our results suggest that forest fragmentation simultaneously affect multiple processes which directly and indirectly affects carbon stocks of different pools. Fragmentation may trigger a process of biotic homogenization, in which a few species are positively related with carbon storage above-, but not below-ground.V. Rolo and P.I. Olivier are supported by post-doctoral grants from the National Research Foundation (NRF) of South Africa. This work was also partly funded by an Ecologists in Africa grant by the British Ecological Society to P.I. Olivier. R.J. van Aarde is supported by Richards Bay Minerals, NRF and the Technology and Human Resources for Industry Programme (THRIP). M. Pfeifer was supported by European Research Council Project number 281986.http://www.elsevier.com/locate/foreco2019-01-01hj2017Zoology and Entomolog

A framework to assess forest-agricultural landscape management for socioecological well-being outcomes

Global demand for agricultural products continues to grow. However, efforts to boost productivity exacerbate existing pressures on nature, both on farms and in the wider landscape. There is widespread appreciation of the critical need to achieve balance between biodiversity and human well-being in rural tropical crop production landscapes, that are essential for livelihoods and food security. There is limited empirical evidence of the interrelationships between natural capital, the benefits and costs of nature and its management, and food security in agricultural landscapes. Agroforestry practices are frequently framed as win-win solutions to reconcile the provision of ecosystem services important to farmers (i.e., maintaining soil quality, supporting pollinator, and pest control species) with nature conservation. Yet, underlying trade-offs (including ecosystem disservices linked to pest species or human-wildlife conflicts) and synergies (e.g., impact of ecosystem service provision on human well-being) are seldom analysed together at the landscape scale. Here, we propose a systems model framework to analyse the complex pathways, with which natural capital on and around farms interacts with human well-being, in a spatially explicit manner. To illustrate the potential application of the framework, we apply it to a biodiversity and well-being priority landscape in the Southern Agricultural Growth Corridor of Tanzania, a public-private partnership for increasing production of cash and food crops. Our framework integrates three main dimensions: biodiversity (using tree cover and wildlife as key indicators), food security through crop yield and crop health, and climate change adaptation through microclimate buffering of trees. The system model can be applied to analyse forest-agricultural landscapes as socio-ecological systems that retain the capacity to adapt in the face of change in ways that continue to support human well-being. It is based on metrics and pathways that can be quantified and parameterised, providing a tool for monitoring multiple outcomes from management of forest-agricultural landscapes. This bottom-up approach shifts emphasis from global prioritisation and optimisation modelling frameworks, based on biophysical properties, to local socio-economic contexts relevant in biodiversity-food production interactions across large parts of the rural tropics.Agrisys Tanzania project was funded through BBSRC Global Challenges Research Fund.https://www.frontiersin.org/journals/forests-and-global-changedm2022Zoology and Entomolog

Patterns of species diversity in coastal forests : case studies on tree and bird assemblages in KwaZulu-Natal, South Africa

Habitat loss and fragmentation drives the current extinction crisis. The processes through which it affects biodiversity, however, are complex and poorly understood. This is especially true for spatially complex regions that comprise a mosaic of land-use types, which often range from protected areas to dense human settlements. In such human-modified landscapes, it is important to determine the extent and impact of changing land-use patterns on biodiversity if we are to meet conservation targets or regain ecosystem services. My analyses of coastal forests in KwaZulu-Natal suggest that extensive loss of forests (82%) incurred an extinction debt, modelled to match the 11 bird species now listed as threatened locally. Forest fragments are now also smaller, fewer, further apart and more encroached by human land uses than in the past. Yet, species interactions with the gradient of habitat conditions that now surround forest fragments may have forestalled the realisation of predicted extinctions. I found that natural matrix habitats adjacent forest fragments (e.g. grasslands and woodlands) may facilitate dispersal, enable species spillover from forest fragments, and buffer forest interiors from changes in abiotic conditions associated with high contrast matrix habitats (e.g. agricultural plantations). However, when natural matrix habitats were transformed, these processes were disrupted, which suggest that the effect of landscape change on coastal forest diversity may stretch beyond forest loss per se and the deterministic extinctions predicted by conventional species-area relationships. Next, I determined that the response of different bird species to habitat fragmentation parameters (i.e. area, connectivity and matrix habitats), depended on life-history traits such as body size, feeding guild and habitat specialization. Extinction risk was, however, not a function of species traits or the fragmentation parameter species responded to. This means that a conservation approach that only focuses on restoring a single fragmentation parameter (e.g. area) may not be successful in halting predicted extinctions, simply because multiple factors may determine extinction risk in coastal forests. The interpretation of biodiversity patterns in fragmented landscapes may, however, also be influenced by spatial scale. I therefore used a fractal-based sampling design to test how sampling at fine, intermediate and coarse scales influences (1) beta diversity of and (2) inferences from the modelled contribution of niche- versus dispersal-based assembly processes in structuring tree and bird assemblages. I showed that inferences from beta diversity are scale dependent. As a result, studies with similar sampling effort and temporal sampling protocol, but with different sampling grains are likely to report dissimilar ecological patterns, which may ultimately lead to inappropriate conservation strategies. This thesis provides information of how land-use changes impact on biodiversity patterns and derived processes in a human-modified landscape. It also highlights some conservation opportunities in the coastal forest landscape mosaic, where conservation and restoration actions should focus on both forest fragments and on the surrounding matrices. The conservation of natural matrices may buffer forest communities from impacts associated with high contrast habitat edges, enhance natural plant regeneration through species spillover, provide important linkages between forest fragments, boost regional diversity and allow coastal forests to track environmental change under changing climatic conditions.Thesis (PhD)--University of Pretoria, 2014.tm2015Zoology and EntomologyPhDUnrestricte