Orientador: Felipe Wanderley Amorim / Resumo: As plantas oferecem recurso alimentar a muitas espécies animais através de diferentes estruturas. Dentre tais estruturas estão os nectários, que são glândulas multicelulares especializadas na produção e secreção de néctar. Estes nectários podem ocorrer tanto em partes reprodutivas como vegetativas, e podem ser florais ou extraflorais. Entretanto, também podem ser classificados quanto a sua função em relação com a polinização, sendo do tipo nupcial (quando sua função está relacionada à polinização) ou extranupcial (quando sua função está relacionada à defesa). Tocoyena formosa (Rubiaceae) é uma espécie comum do Cerrado, cujos nectários extraflorais são visitados por formigas. Entretanto, T. formosa tem um único nectário que desempenha funções multivalentes, podendo ser tanto nupcial, quanto extranupcial. Adicionalmente, a espécie também atrai formigas aos botões no início da fase de desenvolvimento cujas corolas são abortadas. Neste contexto, para melhor compreender a interação entre T. formosa e formigas, este trabalho teve como objetivos: a) caracterizar as estruturas das distintas fases do nectário da espécie e a composição química de seus açúcares; b) determinar se existe mudança estrutural e/ou química que seja correspondente com o papel ecológico de cada estágio; c) analisar a dinâmica de secreção do néctar em cada um dos estágios de atividade do nectário; e d) quantificar o investimento da planta no recurso para a atração de formigas e o efeito destas no êxito reproduti... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Plants offer food resources to many animal species through different structures. Among such structures are the nectaries, which are multicellular glands specialized in nectar production and secretion. Nectaries can occur in both reproductive and vegetative parts, and depending on the location can be regarded as floral or extra-floral. However, they can also be classified according to their function in relation to pollination, being nuptial (when their function is related to pollination) or extranupcial (when their function is related to the defense). Tocoyena formosa (Rubiaceae) is a common species of the Cerrado vegetation, whose extrafloral nectaries are visited by ants. However, T. formosa has a single nectary that performs multivalent functions, which can be both nuptial and extranuptial. In addition, the species also attracts ants to the flower buds at the beginning of the development, whose corollas are prematurely aborted. In this context, to better understand the interaction between T. formosa and ants, the main goals of this study were: a) to characterize the nectary structure as well as the sugar chemical composition during the distinct stages of the organ; b) assess whether nectary structure and nectar sugar composition present changes which correspond to the ecological function of each stage of the nectary; c) analyze nectar secretion dynamics of each phase of the nectary; and d) quantify plant investment in the attraction of ants and the effectivity of ants in pl... (Complete abstract click electronic access below) / Mestre

Orientador: Luiz Carlos Forti / Coorientador: Juliane Floriano Lopes Santos / Banca: Pedro Leite Ribeiro / Banca: Vânia Maria Ramos / Banca: Roberto da Silva Camargo / Banca: Ivone Paschoal Garcia / Resumo: Não disponível / Abstract: Not available / Doutor

Orientador: Fernando Carlos Pagnocca / Banca: Patrícia Valente da Silva / Banca: Carlos Augusto Rosa / Banca: Vanderlei Geraldo Martins / Banca: Andre Rodrigues / Resumo: As formigas cultivadoras de fungo (tribo Attini) são insetos eusociais, os quais formam colônias de centenas até milhões de indivíduos, sendo o fungo a principal fonte de alimentação das larvas e a rainha. Segundo sua fungicultura, elas são divididas em grupos, onde encontram-se as denominadas agricultura de "Lower-Attini" (agricultura das formigas basais) e aquelas com agricultura derivada ou "Higher-Attini". Dentro da agricultura derivada, estão as formigas conhecidas como "cortadeiras", que cortam material vegetal fresco para utilizar como substrato para o fungo mutualista que cultivam, enquanto que as formigas com agricultura basal, usam como substrato exoesqueleto e fezes secas de insetos, sementes, material de serrapilheira e folhas secas. Dentro dos ninhos, constroem câmeras onde mantém o fungo formando uma estrutura em forma de esponja chamada de "jardim de fungo". O substrato é constantemente renovado e o material vegetal, uma vez tendo propiciado o crescimento do fungo é descartado, segundo a espécie de formiga, em câmaras especiais dentro do ninho ou externamente ao ar livre. Ainda, não se sabe muito sobre a estrutura e diversidade das comunidades de micro-organismos associados aos ninhos, apesar do crescente número de publicações a respeito. A biologia das formigas cortadeiras da Argentina é pouco estudada e praticamente não se sabe nada sobre os micro-organismos que encontram-se associados aos jardins de fungos e depósitos de descarte. Neste trabalho, apresentão-se dados sobre as leveduras que habitam e estão relacionadas com os ninhos de três espécies de formigas cortadeiras: Acromyrmex heyeri, Acromyrmex lobicornis e Acromyrmex lundii, assim como a descrição de duas espécies novas de leveduras. Mostram-se também um hábito de forrageamento incomum na espécie... (Resumo completo, clicar acesso eletrônico abaixo) / Resumen: Las hormigas cultivadoras de hongos (Tribu Attini) son insectos eusociales, los cuales forman colonias de cientos hasta millones de individuos, siendo el hongo la principal fuente de alimentación de las larvas y la reina. Según, la fungicultura practicada, pueden ser divididas en grupos, donde se encuentran aquellas con agricultura conocida como "Lower-Attini" (agricultura de las hormigas basales) y aquellas con agricultura derivada o avanzada, "Higher-Attini". Dentro de la agricultura derivada, se encuentran las hormigas conocidas como "cortadoras o podadoras", las cuales cortan material vegetal fresco para utilizar como sustrato para el hongo mutualista que cultivan, mientras que las hormigas con agricultura de tipo basal, utilizan como sustrato exoesqueleto y excrementos secos de insectos, semillas, material de hojarasca y hojas secas. Dentro de los nidos, construyen cámaras donde mantienen el hongo formando una estructura semejante a una esponja denominada, comúnmente, como "jardín de hongo". El sustrato es constantemente renovado y el material vegetal, una vez consumido los nutrientes del mismo, es descartado en cámaras especiales dentro del nido, o bien, depositado exteriormente al aire libre, lo que depende de la especie de hormiga. Hasta ahora, no se sabe mucho sobre la estructura y diversidad de las comunidades de microorganismos que se encuentran asociados a los nidos, a pesar del creciente número de publicaciones hechas al respecto. La biología de las hormigas cortadoras de la Argentina ha sido poco estudiada y prácticamente no se sabe nada sobre los microorganismos que se encuentran asociados a los jardines de hongos y depósito de descarte. Con todo, este trabajo presenta datos sobre las levaduras que habitan y están relacionadas con los nidos de tres especies de hormigas podadoras: Acromyrmex heyeri... (Resumen completo clicar acceso eletronico abajo) / Doutor

O gênero de formigas Octostruma Forel 1912 (Formicidae: Myrmicinae) está restrito à região Neotropical; suas espécies ocorrem do México até a Argentina, são predadoras de pequenos artrópodes e podem nidificar no solo, serapilheira e em epífitas. No presente trabalho, a taxonomia do gênero é revista com base no exame de cerca de 4.000 exemplares. Reconheço 43 espécies de Octostruma, 34 espécies previamente conhecidas são consideradas válidas e redescritas e, portanto, nove são reconhecidas como novas. Além disso, indivíduos de castas e sexos ainda não registrados (machos, gines e ergatóides) são aqui descritos pela primeira vez para diferentes espécies. Novos registros de localidades expandem a distribuição geográfica conhecida para parte das espécies e informações sobre a biologia das espécies a partir de dados de rótulo e observações de campo, somados às poucas informações encontradas na literatura são compiladas neste trabalho. Uma chave de identificação para as operárias de todas as espécies do gênero é fornecida. / The ant genus Octostruma Forel 1912 (Myrmicinae: Attini) is restricted to the Neotropics; their species occur from Mexico to Argentina, are predators of small arthropods and may nest in the soil, leaf litter and epiphytes. In the present work, the taxonomy of the genus is reviewed based in the examination of about 4.000 specimens. Recognize 43 Octostruma species, 34 species previously known are considered valid and redescribed and nine are recognized as new. Moreover, castes and sex of individuals not yet recorded (males, gynes and ergatoids) are described here for the first time for different species. New records expand the distribution known for most species and information about the biology of the species from label data and field observations, added to the little information in the literature are compiled in this work. A key to the worker of all species of the genus is provided.

Orientador: Luiz Carlos Forti / Coorientador: Roberto da Silva Camargo / Banca: Nadia Caldato / Banca: Ivone Paschoal Garcia / Resumo: As formigas cortadeiras Atta (saúvas) e Acromyrmex (quenquéns) são apontadas como as principais pragas de ecossistemas florestais e agrícolas, em razão dos prejuízos que causam ao cortarem as folhas das plantas para o cultivo do fungo simbionte. Esse material vegetal selecionado é transportado para a câmara de fungo, onde passa por várias fases de processamento, desde o corte, à incorporação no jardim do fungo. Tal seleção feita pelas operárias forrageiras é influenciada pelas necessidades nutricionais do jardim de fungo e/ou a ausência de substâncias potencialmente nocivas a colônia. Conhecimento este, evidenciado em estudos que observaram a rejeição de plantas palatáveis quando essas apresentaram substâncias nocivas a colônia, como a cicloheximida (CHX), substância conhecida como fungicida em estudos realizados com formigas cortadeiras. As formigas não são capazes de detectar tal fungicida, mas observa-se uma rejeição retardada, quando o fungicida é incorporado ao jardim de fungo. Esse reconhecimento retardado, hipotetizou que um semioquímico emitido pelo jardim de fungo regula a seleção de plantas por operárias, sendo interpretado como uma comunicação entre o fungo simbionte e as operárias de formigas cortadeiras. Assim, alguns questionamentos são importantes como: as operárias respondem a ação do fungicida alterando seus comportamentos dentro da colônia e quais são? Qual o efeito ocasionado pela a CHX em formigas cortadeiras? Existe uma comunicação através de um volátil s... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Leaf-cutting ants Atta (saúvas) and Acromyrmex (quenquéns) are indicated as the main pests of forest and agricultural ecosystems, due to the damage they cause when cutting the leaves of the plants for the cultivation of the symbiotic fungus. This selected plant material is transported to the fungus chamber, where it goes through various stages of processing, from the cutting, incorporation into the fungus garden. Such selection made by forage workers is influenced by the nutritional needs of the fungus garden and / or the absence of substances potentially harmful to the colony. This knowledge, evidenced in studies that observed the rejection of palatable plants when they presented substances harmful to the colony, such as cycloheximide (CHX), a substance known as fungicide in studies with leaf cutting ants. Ants are not able to detect such fungicide, but a delayed rejection is observed when the fungicide is incorporated into the fungus garden. This delayed recognition hypothesized that a semiochemical emitted by the fungus garden regulates the selection of plants by fodder, being interpreted as a communication between the symbiotic fungus and the workers of cutter ants. Thus, some questions are important as: the workers respond to the action of the fungicide by changing their behavior within the colony and what are? What effect does CHX have on leaf cutting ants? Is there a communication through a volatile semiochemical released by the fungus to promote substrate rejection by... (Complete abstract click electronic access below) / Mestre

Climate change is predicted to impact organismal nutritional ecology. Increased temperatures can directly accelerate physiological rate processes, which in turn, impact nutritional requirements. Climate change can also impact organisms indirectly by altering the quality and quantity of nutritional resources, creating the potential for nutritional mismatch between what nutrients are available in the environment and what organisms require. Investigation of organismal stoichiometry, particularly the balance of carbon, nitrogen, and phosphorus content of organisms, can help illuminate the extent to which changes in climate may impact organism nutritional ecology. Ants represent an excellent system to examine stoichiometry because they occur across a broad range of environmental conditions and perform important ecosystem services, such as seed dispersal, which may impact ecosystem functioning. In this thesis, I examined how climate variables influence ant stoichiometry across a broad latitudinal gradient in natural populations of three closely-related ant species in the genus Aphaenogaster. In a common garden study, I tested the extent to which such stoichiometric variation was due to plastic or evolved variation. I found significant species-specific differences in how ant stoichiometry responded to climate gradients. The northern species, A. picea contained more C, and less N and P at higher latitudes and elevation, consistent with increased winter lipid storage. In contrast, the more southern species, A. rudis, showed the opposite pattern, which may reflect N and P limitation at southern extremes. Aphaenogaster fulva, whose range is intermediate in latitude and partially overlaps with both congeners, contained more C in environments with more seasonal precipitation. Thus, these species appear to use different nutrient storage strategies in response to the variation in abiotic and trophic conditions across their range. When reared under the same feeding regime and thermal conditions, site-level differences in nitrogen storage between a northern and a southern ant population were retained over time and across years, suggesting that adaptive divergence in elemental composition is at least partially responsible for clinal patterns in the field. To connect latitudinal patterns to temporal changes projected under climate change, I evaluated how increases in temperature impact ant stoichiometry and associated functional traits at the individual and colony level using an experimental field mesocosm experiment at two sites, Harvard Forest (HF) and Duke Forest (DF). I examined how experimental increases in temperature impacted ant body size, colony demography, and nutritional status of two Aphaenogaster ant species. I found that Aphaenogaster ants at the northern site, HF, responded positively to direct increases in temperature, with increases in colony biomass, colony size, total reproductive output, and shifts toward increased nitrogen content with increases in temperature. In contrast, Aphaenogaster ants at the southern site, DF, were generally unaffected by temperature except for a decrease in maximum colony size with increases in temperature. Together, my findings provide evidence that both climate variables and evolutionary history impacts ant stoichiometry, which in turn, may impact ant colony fitness. Examination of the biochemical basis of stoichiometric trait variation is needed to ascertain the role stoichiometry may play in how ant species adapt to changing environmental conditions.

Tropical forests of the world are fast disappearing and there is a race to understand patterns of species distribution in space and time. Studying species distributions can provide better frameworks for conservation of these ecologically important patches of floral and faunal diversity. The island of Sri Lanka is a well known harbour of unique and highly threatened biodiversity. Tropical lowland forest is remnant in the south-west of the island now mainly existing in small patches. While most are small disturbed fragments, Sinharaja Forest Reserve represents one of the largest remaining patches of this important ecosystem. As a UNESCO World Heritage Site and a Man and Biosphere Reserve, it has a dual role as a conservation area and a historically important resource forest. While the distribution of vegetation diversity has been well documented, analyses of invertebrate species distributions are lacking. This thesis investigated a key arthropod group, ground dwelling ants, in relation to environmental gradients within the forest. Cumulative results demonstrate the high diversity of the forest patch. In an area representing less than half the reserve, over 173 ground dwelling ant species were found in distinct assemblages throughout the forest. Since the forest is located upon a series of parallel ridges, ant species distribution was first analysed in terms of this small elevation change. Species richness declined over a vertical incline from 430 m to 660 m, highlighting a possible small-scale, mountain mass effect. This section of the reserve is also characterised by a patch of once-logged forest (30 years previously). A study was undertaken to investigate whether there were residual effects of selective logging on the reserve. / Significant differences between species assemblages in once-logged forest and unlogged forest add to growing evidence that selectively logged forests continue to remain distinct from unlogged forest even after decades of regeneration. Ant distribution was then analysed for their relationship with habitat heterogeneity and tree species distribution. Long-term research on tree species in the SFR has demonstrated a close relationship to habitat complexity. Ant species appear to respond more to the structural heterogeneity of the vegetation than to actual topographic variation within the forest. From a conservation perspective, maintaining the integrity of this highly diverse forest is imperative. The impact of anthropogenic land uses surrounding the forest was investigated in terms of ant assemblages along the forest edges. Significant differences were found between assemblages within the edges bordered by different matrix types. Even relatively large forest remnants can be affected by the surrounding matrix land uses and encouraging the growth of structurally similar vegetation and maintaining low disturbance along the borders should attenuate the effect of the edge. Overall, the highly heterogeneous distribution of ant assemblages within the SFR demonstrates the potential for other small patches to be harbours of further species diversity. Future research should be undertaken to assess the diversity and distribution of ant species within this region and encourage the protection of this remnant diversity.

Habitat fragmentation involves the break-up of continuous native vegetation into remnant patches that are set in a matrix of altered habitat. The consequences of habitat fragmentation include the loss of original habitat which is followed by reductions in remnant size that increase edge effects and reduce habitat quality, and also increase the isolation of remnants from one another. Habitat fragmentation is an international environmental concern that also effects Australia. Over the last ten years Queensland has been responsible for some ninety percent of the clearing occurring in Australia, and as a result recorded some of the highest vegetation clearing rates in the world. / thesis (PhDEnvironmentalManagement)--University of South Australia, 2004.

<p>The aim of this thesis is to study phylogeny, species-wide phylogeography and genetic diversity in <i>Formica</i> ants across Eurasia in connection with the history of biotic responses to Quaternary environmental changes.</p><p>The mitochondrial DNA phylogeny of Palaearctic <i>Formica</i> species supported the subgeneric grouping based on morphological similarity. The exception was that <i>F. uralensis</i> formed a separate phylogenetic group. The mitochondrial DNA phylogeny of the <i>F. rufa </i>group showed the division into three major phylogenetic groups: one with the species <i>F. polyctena</i> and <i>F. rufa</i>, one with <i>F. aquilonia</i>, <i>F. lugubris</i> and <i>F. paralugubris</i>, and the third one with <i>F. pratensis</i>.</p><p>West-east phylogeographic divisions were found in <i>F. pratensis</i> suggesting post-glacial colonization of western Europe and a wide area from Sweden to the Baikal Lake from separate forest refugia. In contrast, no phylogeographic divisions were detected in either <i>F. lugubris </i>or<i> F. exsecta</i>. Contraction of the distribution range to a single refugial area during the late Pleistocene and the following population expansion could offer a general explanation for the lack of phylogeographic structure across most of Eurasia in these species.</p><p>Sympatrically distributed and ecologically similar species <i>F. uralensis </i>and<i> F. candida</i> showed clear difference in the phylogeographic structure that reflected difference in their vicariant history. Whereas no phylogeographic divisions were detected in <i>F. uralensis</i> across Europe, <i>F. candida</i> showed a well-supported phylogeographic division between the western, the central and the southern group.</p><p>In socially polymorphic <i>F. cinerea</i>, the overall level of intrapopulation microsatellite diversity was relatively high and differentiation among populations was low, indicating recent historical connections. The lack of correspondence between genetic affinities and geographic locations of studied populations did not provide any evidence for differentiating between alternative hypotheses concerning the directions and sources of postglacial colonization of Fennoscandia.</p>

Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2009.