Biological invasions have increased dramatically in the past centuries and are one of the greatest threats to biodiversity today. Invasions occur when organisms are introduced at a location to which they are non-native, and they reproduce and spread, causing damage to the environment. Chromolaena odorata, a herbaceous shrub from the Americas, is one of the most widespread and problematic invasive plant species in the tropics and sub-tropics. The plant is a serious problem in South Africa, where invasive species threaten the nation’s biodiversity and limited water supply. This study combined transect monitoring data of C. odorata with ecological and clearing management data to assess the efficacy of an invasive plant clearing program over its decade of operation in the Hluhluwe-iMfolozi reserve in KwaZulu-Natal, South Africa. Densities and local extent of the C. odorata invasion were significantly reduced during the period of operations of the clearing program. Seasonal effects impacted clearing efficacy, namely a reduction in efficacy during the seed dispersal period. Effort and fire frequency were positively associated with clearing success, and rainfall negatively associated with clearing success. Excluding the northern section of the reserve, where the invasion progressed over the whole landscape, observations of C. odorata were closer to watercourses than randomized points, indicating a water limitation for invasion in most of the park. Management implications drawn from the results include halting clearing during seed-drop months, giving extra attention to areas with more rainfall and other water availability, and incorporating fire with other clearing methods where possible.

Thesis (M.S. - Renewable Natural Resources)--University of Arizona. / Includes bibliographical references (leaves 96-107).

Thesis (Ph.D.) - James Cook University, 2002. / Typescript (photocopy) Bibliography: leaves 271-298.

Thesis (Ph. D.)--Rhodes University, 2004. / Title from PDF t.p. (viewed on May 2, 2006). Includes bibliographical references (p. 263-293).

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Norma Fowler. Vita. Includes bibliographical references.

A pressão antrópica sobre o cerrado vem transformando sua paisagem em um mosaico de fragmentos naturais imersos em uma matriz antropizada. A qualidade da vegetação dos fragmentos remanescentes depende em grande parte das populações de polinizadores, dos quais as abelhas são o grupo mais representativo. As abelhas sem ferrão (Apidae: Meliponini) compõem a maior biomassa de polinizadores nesse bioma. Seus ninhos são feitos usualmente em cavidades de troncos ou no solo e algumas espécies constróem ninhos expostos. Os fatores que levam os meliponíneos a nidificarem em uma determinada região são, a princípio, a disponibilidade de recursos (sítios de nidificação e alimento) e o comportamento competitivo intra e interespecífico. Mas esses não são os únicos determinantes, pois os fatores que levam as populações a se manterem, se expandirem ou se reduzirem nessa região estão ligados também à resposta de cada espécie ao grau de antropização da paisagem. O objetivo geral dessa tese foi investigar como fatores naturais e antrópicos afetam a nidificação de meliponíneos em ambiente de cerrado, visando responder às seguintes questões: a) Diferenças estruturais entre fitofisionomias de cerrado se refletem na composição de espécies? b) Como a redução das áreas naturais de cerrado e sua substituição por paisagens rurais e urbanas afetam as populações de ninhos de meliponíneos? e c) Como o relacionamento genético e a obtenção de recurso alimentar afetam a distribuição das colônias em uma área de cerrado? Para responder a essas questões, esta tese foi dividida em três capítulos: No capítulo 1, o objetivo foi compreender se e como a distribuição dos ninhos de Meliponini variaria entre três fisionomias de cerrado, campo sujo, campo cerrado e cerradão em Itirapina, SP, e como essa variação estaria relacionada a diferenças na disponibilidade de sítios de nidificação e de alimento em cada uma delas. Foi realizado um levantamento dos ninhos e uma avaliação da quantidade e composição de espécies de árvores em cada uma dessas fisionomias, além da contagem de plantas floridas durante 20 meses. Foram localizados 50 ninhos de Meliponini, sendo 17 no campo sujo (todos de Trigona spinipes), 19 no campo cerrado (18 de T. spinipes e um de Melipona quadrifasciata), 12 no cerradão (cinco de T. spinipes, três de Tetragonisca angustula, dois de Leurotrigona muelleri, um de Trigona hyalinata e um de Plebeia droryana) e dois de T. spinipes fora da área amostrada. A maior quantidade de árvores foi encontrada no cerradão, enquanto o maior número de plantas floridas foi encontrado no campo sujo. No capítulo 2, o objetivo foi avaliar o efeito da substituição das áreas naturais de cerrado por paisagens agrícolas e urbanizadas sobre as populações de Meliponini como um todo, e particularmente sobre abelhas Melípona. Os resultados obtidos em 31 levantamentos de ninhos em áreas de cerrado, além do levantamento feito em Itirapina, foram relacionados ao grau de antropização da paisagem. A avaliação da paisagem foi feita por meio da análise e classificação de imagens de satélite do entorno dos levantamentos. A riqueza de espécies de Meliponini se correlacionou negativamente com a proporção de áreas rurais, mas a composição de espécies se correlacionou positivamente. A composição de espécies se relacionou positivamente ao porte da vegetação também. Por sua vez, a densidade de ninhos e a composição de espécies de Melípona se correlacionaram negativamente com a proporção de áreas rurais. No capítulo 3, o objetivo foi verificar o grau de relacionamento genético e sua influência na distribuição das colônias de T. spinipes na paisagem, a distância utilizada para o forrageamento e o compartilhamento ou não de alimento entre colônias. Para isso, realizamos um estudo com marcadores de microssatélites entre as colônias levantadas no capítulo 1, além um experimento de distância de forrageamento. As colônias vizinhas apresentaram um baixo grau de relacionamento genético entre si, mas as operárias coletadas em uma mesma flor apresentaram alto grau. A distância de forrageamento foi maior que a distância entre colônias vizinhas. Concluiu-se que: a) Fitofisionomias campestres podem apresentar uma abundância de ninhos maior do que fitofisionomias florestais, mas as fitofisionomias florestais podem apresentar uma riqueza maior de espécies. O tamanho da amostra pode subestimar a riqueza de espécies das fitofisionomias florestais. A relação positiva entre a composição de espécies de Meliponini e o porte da vegetação indica que há preferência de algumas espécies por determinada fitofisionomia. No entanto, a detecção de um padrão torna-se difícil dada a ubiquidade das espécies de comportamento mais plástico. b) A antropização pode ter um efeito negativo sobre as populações de Meliponini, podendo levar à perda de espécies. Para espécies de comportamento mais plástico, as áreas antropizadas não oferecem limitação de recursos, mas para espécies de comportamento mais restritivo, a substituição das áreas naturais pode ter um efeito deletério sobre suas populações. c) O baixo grau de relacionamento genético entre colônias próximas indica que não há limitação de fluxo gênico para T. spinipes. A capacidade de suas operárias em dominar um recurso floral pode excluir competitivamente abelhas de espécies menos agressivas. Se a matriz antropizada apresentar limitação de recursos, espécies de comportamento menos agressivo poderão não conseguir obter recursos alimentares, ficando isoladas em fragmentos de áreas naturais. O isolamento pode levar à perda de variabilidade genética e, consequentemente, à perda de espécies. Portanto, políticas de conservação que visem a proteção das espécies de Meliponini devem levar em conta não apenas a quantidade de árvores de uma região, mas também a qualidade e a heterogeneidade da vegetação, tanto nas áreas de proteção ambiental quanto nas áreas entre elas. / The antropic pressure over the Cerrado has been transforming its landscape into a mosaic of fragments surrounded by an antropized matrix. The quality of the vegetation of the remaining fragments largely depends on the pollinators populations, which the bees are the most representative. The stingless bees (Apidae: Meliponini) compound the biggest biomass of this biome. Their nests are usually made inside trunk or soil cavities, but some species make exposed nests. The factors that lead Meliponini to nest in a given region are, at first, the resources availability (nest sites and food) and the intra- and interspecific competitive behavior. However, these are not the sole determinants, because the factors that lead to maintain, expand or reduce populations sizes are also related to the response of each species to the landscape antropization degree. The main general goal of this thesis was to investigate how natural and antropic factors affect the Meliponini nesting in Cerrado areas, seeking to answer the following questions: a) Do structure differences among cerrado phytophysiognomies reflect in Meliponini species composition? b) How do the reduction of Cerrado natural areas and their replacement by rural and urban landscapes affect the Meliponini nest populations? and c) How do the genetic relationship and the obtaintion of food resources affect colony distribution in a Cerrado area? To answer these questions, this thesis was split in three chapters: In chapter 1, the objective was to understand if and how the Meliponini nest distribution would vary among three Cerrado phytophysiognomies, namely campo sujo, campo cerrado and cerradão in Itirapina, SP, and how this variation would be related to differences in nesting sites and food availability in each one of them. A nest survey and an evaluation of the trees amount and species composition were undertaken in each phytophysiognomie, besides flowering plants count over 20 months. We found 50 Meliponini nests, being 17 in campo sujo (all belonging to Trigona spinipes), 19 in campo cerrado (18 of T. spinipes and one of Melipona quadrifasciata), 12 in cerradão (five of T. spinipes, three of Tetragonisca angustula, two of Leurotrigona muelleri, one of Trigona hyalinata and one of Plebeia droryana) and two nests of T. spinipes outside the sampled area. The highest amount of threes was found in cerradão while the highest amount of flowered plants was found in campo sujo. In chapter 2, the objective was to evaluate the effect of replacement of natural Cerrado areas by rural and urban landscapes over general Meliponini populations and particularly over Melípona bees. The results of 31 nests surveys in Cerrado areas besides those conducted in Itirapina were correlated to the antropization degree of the landscape. Landscape evaluation was undertaken by analysis and classification of satellite images from the surveyed surrounding areas. The Meliponini species richness was negatively related to the proportion of rural areas, but species composition was positively related. Species composition was positive related to vegetation size too. I turn, both Melípona nests density and Melípona species composition were negatively related to the proportion of rural areas. In chapter 3, the objective was to verify the degree of genetic relationship and its influence over T. spinipes colony distribution in the landscape, the foraging distance and if there was or was not sharing food among colonies. To accomplish this, a microsatellite markers study was undertaken among colonies found in chapter 1, plus a foraging range experiment. Neighbor nests shown a low genetic relationship degree among them, but workers collected at the same flower showed a high degree of genetic relationship. Foraging distance was farther than the distance between neighbor colonies. We conclude that: a) Grassland phytophysiognomies may show a nest abundance higher than forest phytophysiognomies, but these can show a higher species richness. Sample size can underestimate species richness in forest phytophysiognomies. The positive relationship between Meliponini species composition and vegetation size indicates that there are preferences of some species to some phytophysiognomies. However, the ubiquity of species with a plastic behavior may difficult the finding of a pattern. b) Antropization may have a negative effect over Meliponini population, leading to species loss. To the species with a more plastic behavior, antropized areas do not offer resources limitation, but to species with a more restrictive behavior, the replacement of natural areas may have a deleterious effect on their populations. c) The low degree of genetic relationship among neighbor nests indicates that there is no genetic flow limitation to T. spinipes. The ability of T. spinipes workers to dominate a flower resource may competitively exclude less aggressive bees. If the antropized matrix presents resource limitation, less aggressive species may not obtain food resources, becoming isolated in fragments of natural areas. The isolation may lead to loss of genetic variability and consequentially to species loss. Thus, conservation policies aiming at Meliponini species protection must take in account not only the amount of trees of a given region, but also the quality and heterogeneity of vegetation, as much in areas of environmental protection as the areas among them.

Human beings of all cultures build some form of shelter, and the global distribution of Homo sapiens depends on this basic trait. All great apes (chimpanzee, bonobo, gorilla, and orangutan) build analogous structures (called nests or beds) at least once a day throughout their adult lives, which suggests that this elementary technology was present before the hominid lines separated. This thesis investigates the variability and function of specifically wild chimpanzee shelters. I compared characteristics of chimpanzee nests, nesting trees, nest shape, and architecture in two savanna-dwelling populations on opposite sides of Africa: Fongoli, Senegal, and Issa, Tanzania. Savanna habitats are the most extreme habitats in which chimpanzees survive today, and may represent a similar environment to that in which early hominins evolved in the Plio-Pleistocene (Chapter 2). Investigating variation in nest-building within and between these two extreme habitats made it possible to tackle hypotheses of the shelter function of nests (Chapter 3).The influence of environment, specifically the role of protection from disease vectors and fluctuating temperatures, was assessed through a novel experiment in which I slept overnight in arboreal chimpanzee nests and on the bare earth (Chapter 4). To assess whether or not nests serve as an anti-predation function, I compared nesting in Issa, where predators are abundant, to Fongoli, where they are absent (Chapter 5). I provided further support for the thermoregulatory function of nests by showing that chimpanzees build more insulating nests in adverse weather conditions (Chapter 6).Nest-building is a learned behaviour, but its ontogeny is little known. I investigated social sources of variation in nest building in Fongoli to examine whether sex and age differences exist in nest building duration, nest position, shape and architecture (Chapter 7). Finally, ecosystem engineering is a consequence of animal construction, from ants to humans. I investigated use-wear traces around nests to assess niche construction of nest- building. I showed that chimpanzees repeatedly re-used these specific nest-spots within trees, which are pre-fabricated for future building through repeated pruning and shaping of these structures (Chapter 8).Nest building in great apes may be the foundation of constructivity in hominids. This thesis describes proximate functions and influences on nest-building variation in wild chimpanzees that help to model the evolution of shelter in hominids.

Burkea africana Hook. (wild syringa) is an average sized leguminous tree, 10-12 m in height occasionally reaching over 20m. This monotypic genus is dominant and codominant in Zambia, and is present throughout Africa as far north as Ethopia and west to Nigeria, and south to South Africa especially Limpopo, North West, Gauteng and Mpumalanga. It inhabits dry, non–calcareous sandy soils in savanna and woodlands up to 1500 m altitude or gentle slope of 1080 m elevation. Burkea africana produces a relatively large number of seeds, which is unusual for a resprouting species. Several studies conducted on B. africana trees paid more attention to the medicinal attributes, however little or nothing is known regarding the factors and dynamics that contribute to the growth and existence of these trees, particularly because these trees grow naturally in nutrient-poor savanna soils. Although B. africana trees have been in existence for a very long period of time, propagating it through thinning and transplanting of seedlings for regeneration and/ or re-establishment of seedlings to survive until sexual maturity still remains a mystery. It is hypothesized that factors controlling establishment and development of B. africana trees are related to microbial activities in the soil, very complex and species specific but poorly understood. This study aimed to identify, if there is a symbiotic relationship between the soil and mycorhizal fungi, and rhizobium bacteria or other growth stimulating activities, in the Burkea soils, which will accelerate and assist effective growth of B. africana trees to reach reproductive stage and produce pods without dying. The chemical composition of Burkea soil and non-Burkea soils was analysed using HCl extraction method.). The results indicated the similar values (p>0.05) were observed for all micro and macro minerals as well as total nitrogen, pH and organic matter. However, total ions nitrate and ammonium concentration levels of Burkea soils were higher (p<0.05) than those found in non-Burkea soils. The use of advanced metabolomics tool using1H-NMR was used to determine and identify soil metabolites which may be responsible for successful growth and establishment of the Burkea africana trees. The findings of this study indicated that metabolomic analysis showed different metabolites in the respective soils. Growth-promoting metabolites (GPM) such as trehalose and betaine were found to be in higher concentrations in the Burkea soils. Conversely, acetate, lactate and formate, were found in higher concentrations in the non-Burkea soils. Furthermore, LC-MS was used to determine the soil components present in Burkea soil as compared to non-Burkea soil using. The results indicated that a total of 22 compounds consisted of essential amino acids such as phenylalamine, threonine, tryptophan, leucine, isoleucine and lysine; conditional essential amino acids such as arginine, cysteine, glycine, glutamine, proline and tyrosine; non-essential amino acids such as citruline, alinine, aspartic acids, asparagine, glutamic acid and serine; nucleobased amino acids such as guanosine, adenine, adenosine, cytindine; dicarboxylic acid such as fumaric acid as well as common non-proteinogenic amino acids such as 4-hydroxyproline compounds were found in both Burkea and nonBurkea soils. The study investigated the microbial communities in the soil where Burkea africana trees grows successfully (Burkea soils) and how it varies from the soils where they do not grow (non-Burkea soils). DNA was extracted from the soil and a high throughput sequence bask local assignment search tool (BLAST) was used to analyze the microbial diversity (bacterial and fungal) and composition found in both soils, for a comprehensive understanding of the soil microflora. The results revealed that Penicillum sp is prevalent in Burkea soils and was the main discriminant between the two soils. On the contrary, non-cultured fungi, which could not be identified, dominated the non-Burkea soils. The variances in soil composition suggests that species supremacy play a role in the growth of B. africana trees. Lastly, the current study investigated and also identified what attracts caterpillars known as Cirina forda to invade and feed on B. africana trees. In addition, to determining if there is a symbiotic relationship between the plant-growth metabolites; growth-promoting fungi (Penicilium sp) and the caterpillars. The results of the study, revealed that the fungus Pleurostomophora richardsiae was predominant in the leaves of B. africana trees as well as in the caterpillars. It is proposed that Pl. richardsiae is a volatile compound which attracts caterpillars and makes B. africana trees susceptible to caterpillars’ outbreaks. The second largest percentage of fungi found in the caterpillars was Aspergillus nomius. / School of Agriculture and Life Sciences / Ph. D. (Agriculture)

Perilipin-2 (PLIN2) is a gene that codes for the protein adipophilin, which is responsible for lipid storage in tissues and is associated with obesity and other metabolic diseases including fatty liver. It is generally conserved among primates, including humans. Recent studies show that savanna monkeys (Chlorocebus spp.) in South Africa, which moved to a colder climate, have both increased body mass and a duplication of the PLIN2 gene, presumably in response to colder temperatures. This project investigates variation and selection in the PLIN2 gene in silico among 73 wild savanna monkeys using an established bioinformatics pipeline consisting of command line tools, R packages, and Linux-based programs. We found significant genetic differentiation in the PLIN2 gene region at the taxonomic and population level. There are 45 SNPs outside of Hardy-Weinberg equilibrium, one being a missense variant. Our Tajima’s D results suggest balancing selection in two 1kb regions (12:60604000-60605000, D ~ 2.2, Intron 7-8 and 12:60606000-60607000, D ~ 2.4, 3’UTR). While we did not see clear evidence of any positive selective sweeps, we found 11 SNPs with integrated haplotype scores (iHS) that reach the p<0.05 threshold. Out of these, five are also out of Hardy-Weinberg equilibrium, and eight show an association with ecological variables like insolation and temperature. Humans and savanna monkeys develop obesity and other fatty diseases similarly, and the PLIN2 gene may, in part, be implicated in these diseases. A better understanding of the variation in the PLIN2 gene could provide better insights into metabolic disorders in humans.

No description available.