The potential effect of increased UV-B radiation on photosynthetic activity and related processes in a range of terrestrial Antarctic plant species was investigated; from a chlorophyte alga to a vascular plant (Deschampsia antartica). The relative contribution of the UV-B waveband to photosystem II (PSII) damage was used to construct an action spectrum for those species found to be sensitive to UV-B exposure. Investigation involved non-invasive measurements of photosynthesis using chlorophyll-a fluorescence emission coupled with polarographic measurement of oxygen and infra-red gas analysis of carbon dioxide. Compounds associated with UV-B protection were extracted, and analysed using high performance liquid chromatography. Different species exhibited differing sensitivity to UV-B exposure. Reduction in the efficiency of the light independent stage of photosynthesis and decrease in leaf length were found in D. antarctica. A decline in the potential activity of PSII (dark-adapted chlorophyll-a fluorescence) was found in some cryptogams, but no concurrent decrease in gas exchange parameters. Shorter wavelengths of UV-B were shown to be more effective in depression of PSII efficiency. The first action spectrum for terrestrial Antarctic plants would predict a higher weighted UV-B exposure under ambient ozone, but would expect less damage under stratospheric ozone depletion than the commonly used plant action spectrum. Some of the plants investigated contained increased amounts of UV absorbing flavonoids following UV-B exposure. The morphological changes found in D. antarctica should lower photosynthetic productivity, but are dependent on developmental stage. The action spectrum produced herein would still forecast increased damage to PSII due to early spring ozone depletion, but not as great as previously predicted. Moreover, current levels of UV-B radiation may be more damaging to some species than previously thought based on other plant action spectra.

The successful completion of the early developmental stages in organisms with complex life cycles is crucial to the persistence of a species both at the local and global scale. Thus changes in the abiotic environment experienced during larval and early benthic development can have profound effects on the development and ultimately dynamics of populations of marine invertebrates. The effects of elevated temperature and pCO2 in line with future predictions of anthropogenic climate change, ocean warming and ocean acidification (OA), on the survivorship and growth during early development of marine invertebrates is beginning to be understood, yet the underlying physiological ontogeny driving such changes, and the more subtle effects on physiological performance of climate change drivers, has yet to be distinguished. Therefore the aim of the present study is to investigate the effects of elevated temperature and pCO2 on the developmental eco-physiology of an economically and ecologically important species, the European lobster, Homarus gammarus, to characterise the underlying physiological responses of early development behind responses of survival and growth. The main findings relate to how changing optimal temperature conditions during larval development results in changes in metabolic performance and therefore aerobic scope, ultimately driving survival and growth. Larval stages which exhibit narrower aerobic scope were also sensitive to elevated pCO2 evident as reduced survival, changes to energetic demands and organic content, and reduced calcification. Furthermore, this is the first attempt to characterise the physiological response of early benthic juveniles to climate change drivers. Early benthic juveniles are quite different in underlying physiology to later juveniles and adults, cumulating in this stage being energy limited. Such limitations are expressed as a reduction in aerobic scope in relation to elevated temperature and pCO2, and associated sensitiveness to elevated pCO2 resulting in increased moult related mortalities and the breakdown of haemolymph buffering capacity under combinations of elevated temperature and pCO2. Throughout early development, elevated temperature and pCO2, through underlying physiological responses, may have dramatic effects on the geographic range and successful development of H. gammarus.

Immunity and reproduction are important and costly life-history traits and a large part of eco-immunology focuses on trade-offs between investing in reproduction versus immunity. Male Cape ground squirrels (Xerus inauris) are a good organism to test these trade-offs as they invest heavily in sperm competition, evidenced by their large testes, and exhibit alternative reproductive tactics. My research objective was to determine 1) if testosterone suppresses immunity, or if immunity suppresses testosterone, and 2) if alternative reproductive tactics differ in their investments in immunity and reproduction. I found evidence that testosterone was suppressed after an immune challenge, and that manipulatively increased testosterone had no effect on immunity, body condition or parasites. The dispersing tactic males were in worse condition, had higher parasite abundances, but showed no difference in their innate immune ability to non-dispersing males. Males incur increased costs with dispersal and may focus their energy into reproduction instead of immunity. / October 2015

O presente trabalho objetivou uma melhor compreensão do comportamento ecofisiológico do cafeeiro (Coffea arabica L.) sob diferentes condições de cultivo sejam, intensidade de sombra e demais interações com a seringueira (Hevea brasiliensis Müell. Arg.). Procurou-se evidenciar a competição por luz e água em função da distância das árvores e conseqüente diferente intensidade de competição. As hipóteses desse trabalho são: 1. A redução da disponibilidade de luz pelas árvores afeta o crescimento dos cafeeiros positivamente pela redução da transpiração e negativamente pela redução da fotossíntese líquida expressa como acúmulo de matéria seca da parte aérea; 2. Existe competição por luz entre o cafeeiro e a árvore sombreadora, sendo esta proporcional à distância entre as culturas e ao tamanho da árvore sombreadora; 3. O modelo matemático utilizado descreve adequadamente a disponibilidade de luz à cultura intercalar e pode ser uma importante ferramenta no desenho de sistemas agroflorestais (SAFs). O experimento foi instalado no campo experimental do Dept. de Produção Vegetal da Escola Superior de Agricultura "Luiz de Queiroz" - ESALQ/USP em Piracicaba-SP (22°42’30" S, 47°38’00" W - altitude 554 m) num delineamento em faixas (Strip-Plot), onde a distância do cafeeiro em relação às árvores define um tratamento, com níveis de interações entre as culturas a depender desta variável. De acordo com os dados experimentais obtidos pôde-se concluir que: 1. No intervalo entre 100 a 45% da irradiância disponível não houve redução no acúmulo de matéria seca dos cafeeiros. Maiores reduções da irradiância disponível levaram à diminuição do acúmulo de matéria seca diretamente proporcional, bem como modificações em suas características morfológicas e fisiológicas dada à adaptação a estas condições; 2. O sombreamento teve um efeito positivo na redução da transpiração por unidade de área foliar e por planta. Por outro lado teve um efeito negativo aumentando a transpiração por unidade de irradiância disponível; 3. O modelo matemático proposto por Goudriaan (1977) simulou bem a disponibilidade de irradiância à cultura intercalar, com boa aproximação entre os valores medidos e estimados. Assim, sua disponibilidade está relacionada com a distância e tamanho das árvores sombreadoras. / The main objective of the present work was the better understanding of the ecophysiological interactions within rubber trees (Hevea brasiliensis Müell. Arg.) and coffee plants (Coffea arabica L.). Above and below ground interactions were analyzed as a function of tree distance and consequent competition intensity. The main hypotheses of this research were: 1. Reduction on light availability due to trees affects the coffee plant growth positively by the transpiration reduction and negatively by the net photosynthesis reduction expressed by dry matter accumulation; 2. There are light competition between coffee plants and shade trees, been this proportional to the distance among crops and tree size; 3. The mathematical model used described adequately the light availability to the associated crop and can be an important tool on agroforestry system (AFS) design. The experiment was established in an experimental field belonging to the Dept. of Plant Production - ESALQ/USP at Piracicaba-Brazil (22°42’30" S, 47°38’00" W - altitude 554m) in random blocks with 11 treatments in a "Strip-Plot" design, where interactions intensity between crops were determined by the distances of the coffee plants to the tree. According to the experimental data obtained it was possible to concluded: 1. In the interval of 100 to 45% available irradiance coffee plants did not showed reduction on dry matter accumulation. Further reductions on available irradiance led to reduction on dry matter accumulation directly proportional, as well as to modifications on morphological and physiological characteristics due to its adaptation to these conditions; 2. Shade had a positive effect reducing transpiration per unit of leaf area and per plant. On the other hand had a negative effect rising the transpiration per unit of available irradiance; 3. The mathematical model proposed by Goudriaan (1977) presented a good simulation of the available irradiance to the associated crop, with good approximation between measured and simulated values. So, it availability is related to the distance and size of the shade trees.

Plants are threatened by global change, increasing variability in weather patterns, and associated abiotic stress. Consequently, there is an urgent need to enhance our ability to predict plant community dynamics, shifts in species distributions, and physiological responses to environmental challenges. By building a fundamental understanding of plant stress tolerance, it may be possibly to protect the ecological services, economic industries, and communities that depend on plants. Dehydration tolerance (DhT) is an important mechanism of water stress tolerance with promising translational applications. Here, I take advantage natural variation in DhT to gain a deeper insight into this complex trait. In addition, I address questions related to the causes and consequences of sexual dimorphisms in DhT. Understanding sexual dimorphisms in stress tolerance is critical because these dimorphisms can drive spatial segregation of the sexes, biased sex ratios, and may ultimately reduce sexual reproduction and population persistence. This work takes an integrated approach, addressing DhT on multiple scales from ecology, to physiology, to genomics in the tropical liverwort Marchantia inflexa. Initially, I tested for correlations between DhT and environmental dryness, sex differences in DhT, and genetic vs. plastic contributions to DhT variability. I found that patterns of variation in DhT are associated with environmental variability, including complex sexual dimorphisms, and derive from a combination of plasticity and genetic differences in DhT. Subsequently, I leveraged the variability in DhT to identify candidate DhT enhancing genes. In M. inflexa intraspecific differences in DhT are impacted by baseline variability among plants, as well as unique gene expression responses initiated during drying. In parallel, I assembled a draft genome assembly for M. inflexa, which was employed to investigate questions of sex chromosome evolution and sexual dimorphism in DhT. Finally, the bacteriome of M. inflexa was characterized and found to be extremely diverse and variable. Collectively, this work adds to a growing understanding of DhT and highlights the importance of sampling approaches that seek to comprehensively describe variability in DhT. I detected complex patterns of variability in DhT among populations and the sexes of M. inflexa, which were used to gain insight into the genetic intricacies of DhT.

O presente trabalho objetivou uma melhor compreensão do comportamento ecofisiológico do cafeeiro (Coffea arabica L.) sob diferentes condições de cultivo sejam, intensidade de sombra e demais interações com a seringueira (Hevea brasiliensis Müell. Arg.). Procurou-se evidenciar a competição por luz e água em função da distância das árvores e conseqüente diferente intensidade de competição. As hipóteses desse trabalho são: 1. A redução da disponibilidade de luz pelas árvores afeta o crescimento dos cafeeiros positivamente pela redução da transpiração e negativamente pela redução da fotossíntese líquida expressa como acúmulo de matéria seca da parte aérea; 2. Existe competição por luz entre o cafeeiro e a árvore sombreadora, sendo esta proporcional à distância entre as culturas e ao tamanho da árvore sombreadora; 3. O modelo matemático utilizado descreve adequadamente a disponibilidade de luz à cultura intercalar e pode ser uma importante ferramenta no desenho de sistemas agroflorestais (SAFs). O experimento foi instalado no campo experimental do Dept. de Produção Vegetal da Escola Superior de Agricultura “Luiz de Queiroz” - ESALQ/USP em Piracicaba-SP (22°42’30” S, 47°38’00” W - altitude 554 m) num delineamento em faixas (Strip-Plot), onde a distância do cafeeiro em relação às árvores define um tratamento, com níveis de interações entre as culturas a depender desta variável. De acordo com os dados experimentais obtidos pôde-se concluir que: 1. No intervalo entre 100 a 45% da irradiância disponível não houve redução no acúmulo de matéria seca dos cafeeiros. Maiores reduções da irradiância disponível levaram à diminuição do acúmulo de matéria seca diretamente proporcional, bem como modificações em suas características morfológicas e fisiológicas dada à adaptação a estas condições; 2. O sombreamento teve um efeito positivo na redução da transpiração por unidade de área foliar e por planta. Por outro lado teve um efeito negativo aumentando a transpiração por unidade de irradiância disponível; 3. O modelo matemático proposto por Goudriaan (1977) simulou bem a disponibilidade de irradiância à cultura intercalar, com boa aproximação entre os valores medidos e estimados. Assim, sua disponibilidade está relacionada com a distância e tamanho das árvores sombreadoras. / The main objective of the present work was the better understanding of the ecophysiological interactions within rubber trees (Hevea brasiliensis Müell. Arg.) and coffee plants (Coffea arabica L.). Above and below ground interactions were analyzed as a function of tree distance and consequent competition intensity. The main hypotheses of this research were: 1. Reduction on light availability due to trees affects the coffee plant growth positively by the transpiration reduction and negatively by the net photosynthesis reduction expressed by dry matter accumulation; 2. There are light competition between coffee plants and shade trees, been this proportional to the distance among crops and tree size; 3. The mathematical model used described adequately the light availability to the associated crop and can be an important tool on agroforestry system (AFS) design. The experiment was established in an experimental field belonging to the Dept. of Plant Production - ESALQ/USP at Piracicaba-Brazil (22°42’30” S, 47°38’00” W - altitude 554m) in random blocks with 11 treatments in a “Strip-Plot” design, where interactions intensity between crops were determined by the distances of the coffee plants to the tree. According to the experimental data obtained it was possible to concluded: 1. In the interval of 100 to 45% available irradiance coffee plants did not showed reduction on dry matter accumulation. Further reductions on available irradiance led to reduction on dry matter accumulation directly proportional, as well as to modifications on morphological and physiological characteristics due to its adaptation to these conditions; 2. Shade had a positive effect reducing transpiration per unit of leaf area and per plant. On the other hand had a negative effect rising the transpiration per unit of available irradiance; 3. The mathematical model proposed by Goudriaan (1977) presented a good simulation of the available irradiance to the associated crop, with good approximation between measured and simulated values. So, it availability is related to the distance and size of the shade trees.