A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the academic requirements for the degree of Doctor of Philosophy. August 2016, Johannesburg / Termites are widely distributed in tropical and subtropical savanna. They are recognised as major ecosystem engineers through their role in nutrient cycling, decomposition, hydrology and alteration of landscape topography with cascading effects manifesting in ecosystem heterogeneity and productivity up the food chains. In this thesis I addressed the effect of geology on termite species diversity, followed by questioning how the different geologies influence the size and spatial distribution of Macrotermes mounds. Furthermore, I explored the effect of termite mounds emanating from different geologies on herbaceous vegetation heterogeneity and finally the effect this heterogeneity has on grazing intensity. Although the diversity of termites has been explored across different environmental gradients such as rainfall, altitude and disturbance, little is known regarding variation in their diversity across landscapes of varying geology. In my quest to understand how varying geology influences the ecology of termites and their functional importance, I sampled granite and basalt for termite diversity using standard transects (100 m x 2 m). I predicted that termite diversity is higher on nutrient-rich geology following the productivity diversity hypothesis. However, both functional and taxonomic diversity were higher on nutrient-poor granite. Twelve species from three subfamilies representing two feeding groups were recorded on granite whereas on basalt only five species from two subfamilies consisting of one feeding group were recorded. Although the influence of Macrotermes mounds on ecosystem heterogeneity has been well studied, little is known on how the environment (geology) and other termite colonies influence size and distribution pattern, despite how these interactions could influence ecosystem functioning. Termite mounds were sampled in 1 km2 plots, four in each geology. Each mound location was recorded using a hand held GPS and structural variables (height and diameter) measured. The data were analysed for spatial distribution of termite mounds using the software Programita. The general distribution pattern of termite mounds (active and inactive mounds combined) was investigated using both the pair correlation function, g(r), and Ripley’s K(r) function. Termite mounds were larger and covered a significant proportion of the landscape on granite compared to basalt. Mounds were generally over-dispersed on granite and randomly distributed on basalt. Mounds covered ~ 6% of the landscape on granite compared with only ~ 0.4% on basalt. These results show that the significance of termites varies across geologies, being more important on nutrient-poor geologies because of their size and a more productive spatial pattern displayed here. The majority of studies testing mound effects on savanna vegetation spatial heterogeneity have been based on single site observations mostly comparing mounds and their paired savanna control plots. Furthermore studies did not consider the spatial effects of mounds with distance into the savanna matrix from mound edge, and this has rarely been tested across landscapes of varying geologies, as well as across mounds of different sizes. Therefore there was a need to explore this in order to broadly understand the functional importance of mounds. I sampled the herbaceous community on and off termite mounds and along distance transects from mounds on nutrient-rich and nutrient-poor geologies. Termite mounds as sources of spatial vegetation heterogeneity was more pronounced on nutrient-poor granite, with larger mounds having greater effect on vegetation composition and diversity than smaller ones. Mounds harboured compositionally different herbaceous plants compared with the savanna matrix on granite whereas there was no difference on basalt. In acknowledging the effect erosion from mounds may have on vegetation heterogeneity, termite mound effect on composition expressed at landscape level based on mound densities recorded in this study was estimated to be 19% of the landscape on granite whereas on basalt, the mounds influenced ~ 0.4% of the landscape. The choice of foraging sites by large herbivores in the landscape is influenced by food quantity, quality, inter and intra-specific competition and predation risk. Termite mounds harbour highly nutritious herbaceous plants compared to the savanna matrix, which makes them preferred foraging sites. Due to very small differences in soil nutrient content between mounds and savanna on basalt, mounds were expected to have little effect on grazing. In line with the set hypothesis termite mounds largely influenced grazing on the nutrient-poor granite and when viewed at landscape scale, based on mound densities and extent of erosion recorded, mounds influenced ~ 28% on granite and only ~ 0.8% on basalt. Overall my study has demonstrated that the significance of termites as ecosystem engineers varies across landscapes of varying geology, being more important on nutrient-poor compared with nutrient-rich geologies. / MT2017

A study was initiated in 1981 to investigate the redevelopment of plant communities on a recontoured, surface-mined site in southwestern Wyoming. The landscape pattern of vegetation was compared with topographic position, the initial topsoil pattern, and cultural practices including shrub planting density, shrub planting pattern and topsoil treatments for the years 1982-1985. In addition, differences in vascular plant species diversity within these various factors and treatments were determined, along with the trend in intracommunity (alpha), intercommunity (beta) and landscape (gamma) diversity for the entire study area. The influence of site factors and tested cultural practices on the differentiation of the landscape vegetation pattern generally declined over time. There were no persistent differences in diversity among any cultural treatments or topographic positions, with the exception of plan ting pattern. The vegetation classified by cultural treatment, topographic position, or the initial plant comm uni ties identified in 1982 showed strong successional convergence by 1985. This is reflected in a decline in be ta and gamma diversity over the period 1984-1985. Alpha diversity remained stable over this same period, though species richness increased, indicating that a subset of species is becoming more dominant. The landscape vegetation pattern apparently converged to a rather uniform composition, increasingly dominated by perennial grasses, forbs and shrubs.

Herbivore abundances are determined by a set of interacting factors that vary among different habitat types. Specifically, herbivore abundances in monocultures and polycultures may be governed by the same set of factors but with varying influences in the different habitats. In addition, monophagous and polyphagous herbivores may respond differently to the same set of influencing factors. I examined several abiotic and biotic factors in manipulated monocultures and polycultures of Borrichia frutescens in a west central Florida salt marsh. The experimental plots differed in both plant diversity and aboveground habitat structure to see how each component of diversity contributed to variability in the abiotic and biotic factors and how those factors were related to differences in herbivore abundances. The monoculture treatment involved clipping all above ground non-host plant material to achieve a host plant monoculture. The polyculture treatments involved pinning all non-host plant material to achieve a polyculture with reduced above ground habitat structure. The second polyculture treatment was a control in which the naturally diverse plots were unmanipulated. Two monophagous and one polyphagous herbivores were chosen for this study because of their abundance and availability in the field. The two monophagous herbivores on the host plant Borrichia frutescens were Pissonotus quadripustulatus (Homoptera:Delphacidae) and Asphondylia borrichiae (Diptera: Cecidomyiidae) both of which have been well studied in the field where the current experiment took place. The polyphagous herbivore was Cyarda acutissima (Homoptera: Flatidae), a poorly known invasive from Cuba. Soil salinity and host plant leaf nitrogen content were the abiotic factors measured. Herbivore abundances, percent egg and gall parasitism by parasitoids, spider abundances on host plant stems and ground spider abundances were the biotic factors measured. Both salinity and host plant leaf nitrogen were significantly different among the different treatments with clipped plots having the highest salinity and leaf nitrogen content. Population densities of both of the monophagous herbivores were not significantly different between treatments. The polyphagous herbivore had significantly higher abundances in the pinned and control plots than in the clipped plots. Stem spider abundances were not significantly different among treatments. Ground spiders, however, were significantly more abundant in control and pinned plots than clipped plots. Parasitism of both monophagous herbivores was not significantly different between treatments but was generally higher in the control plots. The results suggest that for monophagous herbivores bottom-up and top-down factors act antagonistically in monocultures but for the polyphagous herbivore, the presence of multiple host plants is more influential in diverse plots even given the higher abundances of generalist predators.

Thesis (M.S.)--University of Pretoria, 2003. / Title from PDF t.p. (viewed Apr. 30, 2006). Includes bibliographical references.

Thesis (M.S.)--Southern Oregon University, 2003. / "A thesis submitted to the Department of Biology and the Graduate School of Southern Oregon University in partial fulfillment of the requirements for the degree of Master of Science in Environmental Education." Includes bibliographical references (leaves 93-89). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

published_or_final_version / abstract / toc / Ecology and Biodiversity / Master / Master of Philosophy

DNR žymenys yra polimorfinių DNR lokusų aleliai, lokalizuoti tam tikrose genomo vietose ir nustatomi naudojant įvairius molekulinės biologijos metodus. Genetinės įvairovės nustatymas ir tyrimas naudojant DNR žymenis gali padėti suprasti daugelio biologinių reiškinių, vykstančių augaluose (ląstelės, organizmo, rūšies lygmenyje), prigimtį. Vykdydami aptariamus tyrimus norime rasti atsakymą į pagrindinį klausimą: kokios naudotų DNR žymenų galimybės kai kurioms augalų biologijos problemoms (genetinių išteklių išsaugojimo, adaptyvumo, populiacijų diferenciacijos, biotinio ir abiotinio streso ir kt.) spręsti? Naudodami įvairius DNR žymenis kaip molekulinius instrumentus, įvertinome genetinės įvairovės lygį pagrindinėse miežių veislėse, sukurtose Baltijos šalyse ir Baltarusijoje, pritaikėme DNR žymenų nustatymo metodus Rubus idaeus, Lonicera ceruleae genetinėse kolekcijose esančių pavyzdžių genotipavimui bei miško medžių (Pinus sylvestris, Piceae abies) rinktinių medžių klonų tapatumo nustatymui; naudodami EST žymenis klonavome ir ištyrėme du genus, dalyvaujančius Solanum tuberosum atsake į biotinį (Erwinia carotovora infekcija) ir abiotinį stresą. Naudodami RAPD metodą ištyrėme Saxifraga hirculus, Piceae abies, Fraxinus excelsior, Taxus baccata, Rubus idaeus, Pinus sylvestris populiacijų genetinę struktūrą, diferenciacijos lygį, kai kurių ekologinių veiksnių įtaką genetinės įvairovės pasiskirstymui populiacijose. / DNA markers are alleles of polymorphic DNA loci that are established using methods of molecular biology and can be used for the identification of specific chromosome region. DNA markers are applied for the detection and analysis of genetic variation. These molecular instruments can help in the understanding of molecular basis of various biological phenomena in plants (loss of genetic diversity, population divergence, adaptivity, response to biotic and abiotic stress, genetic instability et cetera). The use of DNA markers in practical studies requires a careful consideration of the advantages and as well as limitations of various marker techniques. In this review various applications of DNA markers in plant genetic studies including genotyping and characterization of accessions of germplasm collections, assessment of genetic relationships between cultivars, understanding of the genetic variation within and between populations, plant genome analysis and gene cloning are discussed.

No description available.

Urbanisation has increased tremendously over the last 60 years so that more than 50 per cent of the world population now live in cities. This is especially true for in developed countries, but it is expected that developing countries will take the lead in future urban population growth. This increasing trend of urbanisation has severe consequences for the environment, as it fragments and changes natural areas and alter environmental conditions. This has compelled scientists from many different disciplines to focus on the inclusion of humans into ecology as a driving force of change to create a better understanding of urban ecosystems. The diversity of fauna and flora in the urban environment provides a myriad of ecosystem goods (such as food and fuel) and services (e.g. cleaning the air and reducing noise levels). Apart from these tangible benefits, urban green space also provides recreational, educational and social benefits to urban inhabitants. A surprisingly substantial proportion (21‒36 %) of the total urban green space that produces these ecosystem goods and services is located in private yards. This portrays the importance of the flora of this land-use type, but very little is known about garden flora and its potential for conservation. The determinants of diversity and species richness in gardens were found to be different than for semi-natural ecosystems, because of the high anthropogenic influence. One of these is the socio-economic status of the inhabitants. People with higher socio-economic status were found to harbour more diverse species assemblages in their gardens than those of lower socio-economic status. This phenomenon was termed the “luxury concept”. In the Tlokwe City Municipality (TCM), the legacy effects of apartheid created a steep socio-economic gradient as a result of the inequitable distribution of economic, natural and social resources. The aims of this study were to gain information on the flora that is present in the domestic gardens of the TCM and to determine if socio-economic status (SES), a management index (MI) and demographic factors influences the distribution of plant species between these gardens. A total of 835 plant species were recorded from 100 domestic gardens and the majority were of alien origin. This large number of species included some Red Data species, invasive alien species and also many utilitarian species. This portrays gardens as important ex situ conservation habitats, but simultaneously it could also threaten the integrity of our natural ecosystems through the distribution of alien invasive species. The gamma, alpha and beta diversity were determined across five SES classes to describe the patterns of domestic garden plant species diversity in the TCM. In accordance with other studies, correlations showed that the SES of the inhabitants affected the plant species distribution in the study area. This was especially true for the distribution of alien species that are cultivated for their ornamental value. More species were found in areas of high SES than those of lower SES. The other aspect that influenced the distribution of plant species in these gardens were the MI, although this was to a lesser extent than the effect of SES. The confirmation of differences along the SES gradient could be utilised by urban planners and policy makers to correct this imbalance through the provision of urban green spaces where it is needed most. / Thesis (M. Environmental Sciences and Management)--North-West University, Potchefstroom Campus, 2011.

Urbanisation has increased tremendously over the last 60 years so that more than 50 per cent of the world population now live in cities. This is especially true for in developed countries, but it is expected that developing countries will take the lead in future urban population growth. This increasing trend of urbanisation has severe consequences for the environment, as it fragments and changes natural areas and alter environmental conditions. This has compelled scientists from many different disciplines to focus on the inclusion of humans into ecology as a driving force of change to create a better understanding of urban ecosystems. The diversity of fauna and flora in the urban environment provides a myriad of ecosystem goods (such as food and fuel) and services (e.g. cleaning the air and reducing noise levels). Apart from these tangible benefits, urban green space also provides recreational, educational and social benefits to urban inhabitants. A surprisingly substantial proportion (21‒36 %) of the total urban green space that produces these ecosystem goods and services is located in private yards. This portrays the importance of the flora of this land-use type, but very little is known about garden flora and its potential for conservation. The determinants of diversity and species richness in gardens were found to be different than for semi-natural ecosystems, because of the high anthropogenic influence. One of these is the socio-economic status of the inhabitants. People with higher socio-economic status were found to harbour more diverse species assemblages in their gardens than those of lower socio-economic status. This phenomenon was termed the “luxury concept”. In the Tlokwe City Municipality (TCM), the legacy effects of apartheid created a steep socio-economic gradient as a result of the inequitable distribution of economic, natural and social resources. The aims of this study were to gain information on the flora that is present in the domestic gardens of the TCM and to determine if socio-economic status (SES), a management index (MI) and demographic factors influences the distribution of plant species between these gardens. A total of 835 plant species were recorded from 100 domestic gardens and the majority were of alien origin. This large number of species included some Red Data species, invasive alien species and also many utilitarian species. This portrays gardens as important ex situ conservation habitats, but simultaneously it could also threaten the integrity of our natural ecosystems through the distribution of alien invasive species. The gamma, alpha and beta diversity were determined across five SES classes to describe the patterns of domestic garden plant species diversity in the TCM. In accordance with other studies, correlations showed that the SES of the inhabitants affected the plant species distribution in the study area. This was especially true for the distribution of alien species that are cultivated for their ornamental value. More species were found in areas of high SES than those of lower SES. The other aspect that influenced the distribution of plant species in these gardens were the MI, although this was to a lesser extent than the effect of SES. The confirmation of differences along the SES gradient could be utilised by urban planners and policy makers to correct this imbalance through the provision of urban green spaces where it is needed most. / Thesis (M. Environmental Sciences and Management)--North-West University, Potchefstroom Campus, 2011.