As angiospermas são um dos grupos mais diversos de organismos, e grande parte dessa diversidade deve-se às muitas formas florais existentes. Devido a isso, determinar os padrões de variação floral e os fatores históricos e ecológicos que levaram à evolução desta alta diversidade floral é essencial para entender os processos que dirigem a diversificação das angiospermas. A tribo Bignonieae (Bignoniaceae) representa um excelente modelo para o estudo de diversificação floral na região Neotropical, por ser o clado mais diverso de lianas neotropicais e apresentar uma altíssima diversidade floral. Nesta tese, utilizei a tribo Bignonieae para caracterizar: (i) o padrão de evolução de caracteres florais discretos e morfologias florais, assim como possíveis associações entre as morfologias florais e grupos de polinizadores, (ii) o sinal filogenético e as taxas de evolução de caracteres florais contínuos, (iii) o padrão e a magnitude de integração fenotípica entre caracteres florais contínuos ao longo da filogenia do grupo e (iv) a influência da filogenia, da morfologia floral e de fatores abióticos para a co-ocorrência de espécies e a estrutura de comunidades de Bignonieae. Os resultados indicam grande labilidade na evolução de caracteres discretos e morfologias florais, contrapondo o sinal filogenético encontrado para os 16 caracteres contínuos avaliados. O sinal filogenético, entretanto, difere entre caracteres de cálice-corola e estame-estigma. As taxas de evolução também variam entre caracteres, indicando a ação de diferentes pressões seletivas ou resposta diferencial à seleção em diferentes partes da flor. Os padrões de integração fenotípica se mantêm constantes ao longo da história evolutiva de Bignonieae, apesar da evolução homoplástica da magnitude das correlações entre caracteres. Essa aparente complexidade evolutiva, sugerida pela presença de padrões diferentes em diferentes tipos de caracteres, não se repete na estrutura ecológica das comunidades, já que nem a morfologia floral e nem a filogenia influenciam a co-ocorrência entre espécies. Por outro lado, há evidente especialização das espécies a fatores abióticos, sugerindo um papel crítico de filtro ambiental na estrutura das comunidades de Bignonieae. Esse resultado contraria a hipótese de que saturação causada por competição por polinizadores seria o fator determinante da estrutura interna de comunidades de Bignonieae. / Flowering plants represent one of the most diverse groups of organisms in the Planet. A large portion of this diversity results from the multitude of floral forms encountered nowadays. To understand the patterns of floral variation and of the historical and ecological factors that led to the evolution of such diversity in floral forms are critical for a better understanding of the processes that led to the diversification of angiosperms. The tribe Bignonieae (Bignoniaceae) is the most diverse clade of Neotropical lianas and represents an excellent model for the study of floral evolution due to the high diversity of floral forms of this group. In this Ph.D. thesis, I aimed to characterize: (i) the pattern of evolution of discrete floral traits and floral morphologies in Bignonieae, as well the potential associations between floral morphologies and pollinators; (ii) the phylogenetic signal and the rates of evolution of continuous floral traits; (iii) the pattern and the magnitude of phenotypic integration among floral traits across the phylogenetic history of the group; and, (iv) the influence of phylogeny, floral morphology and abiotic factors for the patterns of species co-occurrence and the structure of communities of Bignonieae in the Neotropics. The results indicate high lability in the evolution of discrete floral traits and floral forms, contrasting the significant phylogenetic signal encountered in all 16 continuous floral traits examined. However, the phylogenetic signal differs between traits of different floral whorls. The rates of evolution also varied among different characters, suggesting the action of different selective pressures or differential responses to selection in different floral parts. Overall, the patterns of phenotypic integration were constant during the history of Bignonieae, despite the homoplastic evolution of the magnitude of correlation among characters. This apparent evolutionary complexity, leading to different patterns in different traits, is not reflected in the ecological structure of communities, given that nor floral morphology or phylogeny influence species co-occurrence. On the other hand, species specialization to abiotic factors was encountered, suggesting that environmental filtering played a key role in the structure of communities of Bignonieae. The results reject the hypothesis that saturation caused by competition for pollinators would be the main factor determining the intra-community structure of Bignonieae.

The effects of food quantity on the morphology and development of the paper wasp Polistes metricus Say are studied, and experimental results are compared with predictions of the parental manipulation hypothesis. Food deprivation led to smaller female offspring. By hand feeding larvae we used a technique that counteracts the queen's hypothesized ability to restrict food provisioning. Hand feeding larvae did not result in larger offspring, but their abdomen was wider and heavier and the hand-fed wasps survived longer in a cold test. We infer that hand-fed colonies produced more gynes and fewer workers than did control colonies. Results of a restricted nourishment treatment do not support the differential feeding hypothesis, because in fasting colonies the emergence of all larvae was delayed by a month, and we did not detect discriminatory feeding of particular larvae for faster emergence. Although fasting colonies produced fewer offspring, the sex ratio did not show significant differences from the other groups. These data suggest that Polistes metricus colonies are partly able to respond to different nutritional conditions by allocating excess food to increase the number of gynes at the expense of workers.

The purpose of this study was to quan ti tate the populations o f lymphocytes in the s pleens and intestines of normal and immunosuppressed adult C57BL/6N mice that were noninfected or infected with Cryptosporidi um parvum. This was accomplished by using the following methodologies: immunohistochemistry, ELISA-spot assay, and flow cytometry. Mice in groups 1 and 2 were immunosuppressed, but only group 2 was in fected. Mice in group 3 were only infected, whereas group 4 served as the normal control . Mice were immunosuppressed with dexamethasone (DEXI at a dosage of 125~g / mouse/day. Infected mice received 106 oocysts per os . The numbers o f lymphocytes were monitored from day 0 to day 18 postinfect i on. Flow cytometry using antibodies directed against CD4+ and CDS+ T cells (helper and cytotoxic, respectively) and B cells (expressing IgG, IgM, and IgA receptors) revealed that c. parvum did not evoke an alteration in the phenotypic profile of lymphocytes within spleens or Peyer's patches (PP) of mice in groups 2 and 3 that was statist i cally different from groups 1 and 4. Immunosuppressed mice (groups 1 and 2) had significantly fewer lymphocytes (bearing CD4+, IgG, IgM, and IgA receptors) within the spleen when compared with mice in groups 3 and 4 (P

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<p>Plants and mycorrhizal fungi form a mutualism in which plants donate carbon to the fungus and, in return, receive benefits such as increased nutrient uptake and water. Mycorrhizal fungi colonize plant roots, forming nutrient exchange structures. The fungi also colonize the soil by growing long strands of hyphae that forage for nutrients and attach plants, forming a common mycorrhizal network (CMN). Plants attached to a well-supported CMN will receive greater benefits than those attached to a lesser CMN because the more carbon donations the fungal partner receives, the more it can grow and colonize the soil, accessing hard to reach soil nutrients. Kin selection theory predicts that relatives should donate more carbon to the fungal partner than non-relatives because benefits gained by neighbouring relatives through the CMN lead to inclusive fitness gains. Thus, social environment, i.e. relatedness of the group, could affect the mycorrhizal mutualism. Moreover, the presence of mycorrhizal fungi in the soil could affect plant responses to their social environment.</p> <p>For my PhD thesis I have investigated whether mycorrhizal fungi respond to plant social environment and whether the presence of mycorrhizal fungi affects plant responses to relatedness. I have addressed these topics in three greenhouse studies and two field studies, using herbaceous plants and trees. I have found strong evidence that siblings have an increased association with their mycorrhizal partner compared to strangers, resulting in greater benefits for siblings. Taken together, the results from this thesis demonstrate that the ability for plants to recognize kin has implications beyond intra-specific competitive interactions and that plant social environment has important effects on a widespread inter-specific mutualism. Additionally, the recently discovered phenomenon of plant kin recognition has been put into the context of mycorrhizae, and I have shown that mycorrhizal plants respond differently to their social environment than non-mycorrhizal plants.</p> / Doctor of Philosophy (PhD)

In the past two decades, molecular cell biology has transitioned from a traditional descriptive science into a quantitative science that systematically measures cellular dynamics on different levels of genome, transcriptome and proteome. Along with this transition emerges the interdisciplinary field of systems biology, which aims to unravel complex interactions in biological systems through integrating experimental data into qualitative or quantitative models and computer simulations. In this dissertation, we applied various systems biology tools to investigate two important problems with respect to cellular activation dynamics and reprograming. Specifically, in the first section of the dissertation, we focused on lipopolysaccharide (LPS)-mediated priming and tolerance: a reprogramming in cytokine production in macrophages pretreated with specific doses of LPS. Though both priming and tolerance are important in the immune system's response to pathogens, the molecular mechanisms still remain unclear. We computationally investigated all network topologies and dynamics that are able to generate priming or tolerance in a generic three-node model. Accordingly, we found three basic priming mechanisms and one tolerance mechanism. Existing experimental evidence support these in silico found mechanisms. In the second part of the dissertation, we applied stochastic modeling and simulations to investigate the phenotypic transition of bacteria E.coli between normally-growing cells and persister cells (growth-arrested phenotype), and how this process can contribute to drug resistance. We built up a complex computational model capturing the molecular mechanism on both single cell level and population level. The paper also proposed a novel way to accelerate the phenotypic transition from persister cells to normally growing cell under resonance activation. The general picture of phenotypic transitions should be applicable to a broader context of biological systems, such as T cell differentiation and stem cell reprogramming. / Ph. D.

All species on Earth occupy limited geographic space. More than a century of observational, experimental, and theoretical work investigating the factors that drive species distributions have demonstrated the importance of the interactions between abiotic, biotic, and demographic factors in determining why species are found where they are. However, it is still unclear when and where these factors interact to set species range limits. Filling the existing knowledge gaps is imperative for the accurate predictions of how species will respond to global change, and particularly for invasive species, many of which are expected to benefit from global change. Here, I sought to investigate the mechanisms that enable, as well as limit, the range expansion of the globally invasive plant Sorghum halepense (L.) Pers. (Johnsongrass). I performed a series of field and laboratory experiments to study population and range dynamics throughout Johnsongrass's North American distribution, and test for the effects of climate, local habitat, and competition on multiple functional traits. I found Johnsongrass consistently demonstrated impressive performance across varying environments, often growing more than 3 m tall, producing hundreds of flowering culms within a single growing season, and maintaining positive population growth rates, even under intense competition with resident weeds. I also found evidence that seed germination has adapted to varying climates encountered during Johnsongrass's range expansion resulting in a shift in the germination temperature niche from warmer to cooler as Johnsongrass spread from warmer climates in the south to more temperate climates in higher latitudes. This shift in the germination temperature niche may have been an important contributing factor in the range expansion of Johnsongrass by enabling the optimization of seed germination in varying climates. On the other hand, results from a field study suggested a possible trade-off between flowering time and growth in populations originating from the range periphery (i.e., range boundary) which may be limiting, or slowing, continued range expansion of Johnsongrass. Together, the outcomes of this work contribute to our understanding of the factors involved in the distribution of species, which is a fundamental goal of Ecology, and essential to accurately predict how invasive species will respond to global change. / Doctor of Philosophy / Invasive species threaten our natural ecosystems, our agricultural systems, and even our infrastructure, and we spend billions of dollars each year attempting to control them and reduce their negative impacts. Climate change, habitat destruction, and other forms of global change, will benefit many of these species, magnifying their impacts and promoting their invasion into new territories. Because of the damaging effects of invasive species, and the costs to control them, it is imperative that we are able to predict how they will respond to global change so that we can improve plans to reduce their impact and spread. First, we need to understand the processes that promote their invasion across large swaths of land. Just as importantly, we must study the processes that prevent their invasion of certain areas. Here, I investigated some of the processes that have facilitated, as well as hampered, the spread of the invasive plant Johnsongrass. For this work, I used Johnsongrass plants originating from different habitats, including regions where Johnsongrass is highly invasive and those where Johnsongrass is very rare. I found Johnsongrass originating from regions where it is highly invasive were able to grow very large and produce thousands of seeds that were able to germinate under a range of conditions. These traits may have contributed to the invasion success of this species. However, I found a different pattern for plants that originated from regions where Johnsongrass is rare. These plants reached reproductive age earlier and grew smaller across all environmental conditions, potentially due to the less hospitable climates of these range edges. These findings allow us to project into future climate change scenarios, because it is likely that, as temperatures warm, invasive species will be able to invade new regions, where they will impact the work of conservationists, natural resource professionals, agricultural produces, and other land managers.