A cana-de-açúcar é uma gramínea C4 de alta biomassa que acumula grandes quantidades de sacarose e é utilizada para produção de etanol, um combustível de baixa emissão de carbono. Restrições bióticas e abióticas afetam significativamente a produtividade das culturas, pois elas podem prejudicar severamente o crescimento e desempenho da planta. Compreender as bases moleculares para essa perda de produtividade ajudará na investigação das estratégias de mitigação. Para estudar estes dois tipos de estresses, plantas jovens de cana-de-açúcar foram submetidas à herbivoria e à privação de água. Uma investigação foi realizada para estudar as mudanças transcricionais em cana-de-açúcar sujeita ao ataque da Diatraea saccharalis, usando macroarranjo para monitorar a seleção de transcritos, contendo sequências de ESTs de serina proteases e inibidores de serina proteases de cana-de-açúcar do banco de dados SUCEST. Análises do macroarranjo revelaram sequências diferencialmente expressas em resposta à herbivoria. PCR em tempo real confirmou que 10 ESTs homólogos à inibidores de protease (4 homólogos aos inibidores do tipo Bowman-Birk de arroz e milho (BBI), 5 homólogos à inibidores de proteinase de milho (MPI) e 1 homólogo ao inibidor de subtilisina) e 3 ESTs homólogos à serina proteases das famílias S1, S10 e S14 foram positivamente regulados pela herbivoria. Embora a função dos inibidores de protease na defesa está bem estabelecida, o envolvimento de proteases de planta na resposta à herbivoria ainda precisa ser elucidado. Neste trabalho nós mostramos que uma protease da família S14 foi induzida em resposta ao ataque da lagarta e ao ferimento mecânico em cana-de-açúcar. Curiosamente, sequências homólogas de arroz e Arabidopsis também responderam aos mesmos tratamentos, sugerindo um papel conservado desta protease S14 na defesa contra herbívoros. Uma importante aplicação destes resultados é a identificação de genes para utilização em estratégias biotecnológicas para melhorar a resistência da cana-de-açúcar a insetos. Outra investigação foi realizada para estudar os parâmetros fisiológicos e perfis transcricionais de genes responsivos ao estresse hídrico em plantas jovens de cana-de-açúcar. Resultados deste trabalho indicaram que a interrupção da irrigação resultou em efeitos fisiológicos mensuráveis e análises de expressão de genes selecionados de resposta ao estresse revelaram expressão diferencial significativa entre os grupos irrigado e não irrigado. Resultados do RNA-Seq revelaram atividade transcricional de 24.142 transcritos de folhas de cana-de-açúcar submetidas à seca. Análises de expressão gênica em resposta à seca revelaram 68 (resposta precoce) e 2.390 (resposta tardia) transcritos diferencialmente expressos no 3º e 7º dia de tratamento, respectivamente. O decréscimo em vários parâmetros fisiológicos foi observado depois de seis dias de privação de água. Reduções na taxa de fotossíntese, condutância estomática e transpiração foliar ocorreram antes que fossem observadas alterações físicas visíveis, mas estas foram precedidas por mudanças significativas na expressão de genes com papel na fotossíntese. RNA-Seq identificou novos transcritos com papéis na defesa precoce e tardia à seca e a validação por PCR em tempo real confirmou os resultados obtidos pelo RNA-Seq. Isto irá incentivar mais pesquisas sobre a eficiência do uso da água em cana-de-açúcar, levando a identificação de variedades com maior tolerância às condições ambientais adversas. / Sugarcane is a high biomass tropical C4 grass crop which accumulates large quantities of sucrose and is used for bioethanol production, a low-carbon emission fuel. Biotic and abiotic constraints significantly impact crop productivity, because they can severely impair plant growth and performance. Understanding the molecular basis for this loss in productivity will aid in identifying strategies for mitigation. To study these two types of stresses, young sugarcane plants were subject to herbivore and water privation. An investigation was undertaken to study the sugarcane transcriptional changes following Diatraea saccharalis damage, using macroarrays to monitor a selection of transcripts, containing sequences of sugarcane ESTs of serine proteases and serine proteinase inhibitors from the SUCEST (Sugarcane EST Project) database. Macroarray analyses revealed differently expressed sequences in response to herbivory. Real-Time PCR confirmed that 10 ESTs homologous to proteinase inhibitors (4 homologous to maize and rice Bowman-Birk inhibitors (BBI), 5 homologous to maize proteinase inhibitors (MPI) and 1 homologue to subtilisin inhibitor) and 3 ESTs homologous to serine proteases of the S1, S10 and S14 family were positively regulated by herbivory. While the protease inhibitor\'s function in defense is well established, the involvement of plant proteases in response to herbivory still remains to be elucidated. In this work we show that a sugarcane encoding S14 family protease member was upregulated in response to both D. saccharalis damage and wound treatment. Interestingly, homologous sequences from rice and Arabidopsis also responded to the same treatments, suggesting a conserved role of this S14 protease in defense against herbivores. One important application of these results is the identification of genes for use in biotechnological strategies to improve sugarcane insect resistance. Another investigation was undertaken to study the physiological parameters and transcriptional profiles of genes responsive to water stress in young sugarcane plants. Results of this work indicated that termination of irrigation resulted in measurable physiological effects in sugarcane plants and analysis of the expression of the chosen stress-response genes revealed significant differential expression between the control and treatment groups. RNA-Seq results revealed transcriptional activity of 24.142 transcripts from sugarcane leaf subjected to water stress. Gene expression analyses in response to water deprivation revealed 68 (early response) and 2,390 (later response) differentially expressed transcripts on day 3 and day 7, respectively. Sustained decreases in various physiological parameters were observed in water-stressed sugarcane plants after six days of water deprivation. Reductions in photosynthesis rate, stomatal conductance and leaf transpiration occurred before visible physical changes were observed, but this was preceded by significant changes in expression of genes with roles in photosynthesis. RNA-seq identified novel transcripts with roles in early and late response to drought stress and Real-Time qPCR validation confirmed the RNA-Seq results. This will inform further research on water use efficiency in sugarcane, leading to identification of varieties with improved tolerance to adverse environmental conditions.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-10-17T21:12:32Z No. of bitstreams: 1 Disserta??o - definitiva! Mar?lia Santos_RGV.pdf: 1618280 bytes, checksum: a6213dfbd6c8106d7bdcae3f7afaca5f (MD5) / Made available in DSpace on 2016-10-17T21:12:32Z (GMT). No. of bitstreams: 1 Disserta??o - definitiva! Mar?lia Santos_RGV.pdf: 1618280 bytes, checksum: a6213dfbd6c8106d7bdcae3f7afaca5f (MD5) Previous issue date: 2016-03-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB / This research addresses a study of methods of collection and phenological data analysisofHimatanthus bracteatus(A. DC.) Woodson e H. drasticus (Mart.) Plumel(Apocynaceae), and investigate their phenological patterns, relating them to the morphological and functional characters, biotic and abiotic factors. Monthly observations of leaf and reproductive phenology, and herbivory activity of these species were performed. We analyzed the leaf traits, water potential, chlorophyll and wood density (in dry months and rainymonths), and floral biology and floral visitor?s aspects. The normality of the data was tested by setting the corresponding regression and correlation tests. The morphological and functional characters were subjected to analysis of variance, considering each month as a treatment. In this study the quantitative method and the circular analysis were identified as the most appropriate for the intensity analysis and phenological timing of the species. The species were evergreen, with annual flowering and extend fruiting, overlaying all phenophases. Synchrony was note between reproductive phenophases. We identified the Pseudosphinx tetrio as a leaf predator. The precipitation was the trigger for the development of these caterpillars, observed in the host in rainy months. The morphofunctional characters showed water reserves in the stem of both species. The herbivorous activity had relationship with mature leaves and budding.The flowering became more intense in the absence of caterpillars. Thefloral morphology and biologyidentified phalenophily as the pollination syndrome. The aggregation and phenological patterns seems to be related to herbivory and pollination processes ofH. bracteatus and H.drasticus. / Essa pesquisa aborda um estudo de m?todos de coleta e an?lise de dados fenol?gicos de Himatanthus bracteatus(A. DC.) Woodson e H. drasticus(Mart.) Plumel (Apocynaceae), e investiga os seus padr?es fenol?gicos, relacionando-os com os caracteres morfofuncionais, fatores bi?ticos e abi?ticos. Para tanto, foram realizadas observa??es mensais da fenologia foliar e reprodutiva, e da atividade herb?vora dessas esp?cies. Analisamosos atributos foliares, potencial h?drico, clorofila e densidade da madeira (em meses de seca e chuva, durante o per?odo de estudo), aspectos de biologia floral e visitantes florais.A normalidade dos dados foi testada, definindo os testes de regress?o e correla??o correspondentes. Os caracteres morfofuncionais foram submetidos ?an?lise de vari?ncia, considerando cada m?s como um tratamento.Neste estudo o m?todo quantitativo e a an?lise circular foram identificados como os mais adequados para a an?lise de intensidade e sincronia fenol?gica das esp?cies. Em ambas as esp?cies, constatou-se padr?o perenif?lio,flora??o e frutifica??o anuais e longas, com sobreposi??o em todas as fenofases e forte sincronia entre as fenofases reprodutivas. Identificou-se a Pseudosphinx tetriocomo predadora, sendo a precipita??o o gatilho para o desenvolvimento destas, as quais foram observadas nos hospedeiros em meses chuvosos. Os caracteres morfofuncionais apontaram reserva h?drica no caule de ambas as esp?cies. A atividade herb?vora teve ainda rela??o com folhas maduras e brotamento.Aflora??o foi mais intensa na aus?ncia das lagartas.A morfologia e biologia floral apontam para a fanelofilia como s?ndrome de poliniza??o das esp?cies. A agrega??o e padr?esfenol?gicosparecem estar relacionados com a herbivoria e s?ndrome de poliniza??o em H. bracteatus e H.drasticus.

Muitas teorias, englobando diferentes fatores e mecanismos, já foram postuladas para explicar a alta coexistência de espécies arbóreas nos trópicos, a qual permanece como uma questão intrigante e subentendida na ecologia vegetal. O estudo da dinâmica de árvores ao nível populacional contribui e embasa, por sua vez, o entendimento desses fatores e mecanismos atuando ao nível da comunidade. O objetivo geral do presente estudo foi investigar alguns aspectos relacionados com a dinâmica de uma espécie arbórea comum Calophyllum brasiliense Camb.(Clusiaceae) em floresta de restinga alta Ilha do Cardoso, Cananéia, SP. Para isso, além de termos testado se a sobrevivência e o desempenho de suas plântulas estavam relacionados com níveis de herbivoria dependentes da densidade, testamos se a ocorrência da espécie apresentava associação com hábitats de solo e caracterizamos sua distribuição espacial na área de estudo. Na Introdução Geral (Capítulo 1) nós enumeramos as principais teorias já propostas para explicar a alta diversidade tropical, as quais incluem diversos mecanismos atuantes na dinâmica de espécies arbóreas. Tradicionalmente, modelos que focam em fatores dependentes da densidade eram freqüentemente contrastados com modelos baseados na segregação de hábitats e nichos para explicar a coexistência de espécies, ainda que atualmente sabe-se que atuem concomitantemente na estruturação das comunidades. Por esse motivo, os descrevemos em linhas gerais. Apresentamos, também, como o estudo da distribuição espacial de uma espécie pode dar indícios de processos subjacentes responsáveis pelos padrões gerados, os quais devem ser inferidos e posteriormente testados. Adicionalmente, resumimos uma teoria em especial, a qual embasa o capítulo seguinte e foi o ponto inicial dessa dissertação: o Modelo Janzen-Connell. Além de termos explorado brevemente seu contexto conceitual, também revisamos os principais resultados de investigações de seus efeitos em outras áreas de estudo e com diferentes metodologias. Como os dois demais capítulos foram desenvolvidos utilizando a mesma área e espécie de estudo, também incluímos neste capítulo suas respectivas descrições. Para testar o modelo Janzen-Connell (Capítulo 2), nós delineamos um experimento no qual avaliamos os danos por herbivoria, a mortalidade e o desempenho das plântulas de C. brasiliense, sob diferentes tratamentos: proteção contra herbivoria, distância e agrupamento de adultos coespecíficos. Encontramos que os efeitos dependentes da distância e da densidade não atuaram como previsto pela teoria para a espécie de estudo, a qual, apesar de ter sofrido altos danos por herbivoria, mostrou-se tolerante e apresentou crescimento compensatório em resposta a estes. Além de termos proposto que a pressão por seus herbívoros especialistas parece encontrar-se amplamente distribuída na área de estudo, e não agregada ao redor de densidades de coespecíficos, também sugerimos que o micro-hábitat, especialmente a umidade do solo parece ser melhor preditora da sobrevivência da espécie do que a herbivoria. No Capítulo 3, portanto, testamos a ocorrência de associação da espécie com o hábitat de solo, como proposto no capítulo 2. Para isso, adotamos uma abordagem conjunta com o estudo da distribuição espacial, possibilitando a inferência de outros mecanismos possivelmente relacionados com a dinâmica da espécie, além do micro-hábitat. Caracterizamos o padrão de distribuição espacial através do uso de metodologias espaciais de segunda-ordem complementares: K-Ripley e O-ring, e testamos a questão da associação com hábitat a partir de torus translation, uma metodologia relativamente nova que incorpora a autocorrelação espacial entre troncos coespecíficos. Além de detectarmos um padrão de distribuição agregado, com escalas críticas de agregação variáveis entre as classes de tamanho investigadas, encontramos que a espécie apresenta uma associação positiva com o tipo de solo alagável (Neossolo), onde sua densidade relativa foi 30% maior em comparação com os outros tipos de hábitat. Os adultos, além de terem se mostrado positivamente associados a esse solo, também apresentaram uma associação negativa com os solos mais arenosos e menos úmidos. Os jovens, encontrados em relativamente baixa densidade, não mostraram associação com nenhum hábitat de solo. Sugerimos que a tolerância ao encharcamento e à condições anóxicas, bem como a ocorrência de hidrocoria como uma de suas formas de dispersão, os principais fatores favoráveis à sua sobrevivência e rápido desenvolvimento ontogenético nessas condições de solo. Utilizamos informações sobre a ecologia de C. brasiliense já disponibilizadas por outros estudos para inferir ou excluir possíveis fatores relacionados com sua distribuição espacial, e a associação com hábitat e o experimento de herbivoria (Capítulo 2) como testes desses possíveis fatores. Nas considerações finais, reunimos todas as informações propostas e testadas sobre os mecanismos que atuam na dinâmica de C. brasiliense e sugerimos que o padrão espacial agregado detectado para a espécie pode ser decorrente da interação entre três fatores principais: (1) associação diferenciada com ambos tipos de solos, alagáveis e arenosos; (2) ocorrência simultânea e complementar de três agentes dispersores da espécie (vento, morcego e água) e (3) alta competição intra-específica dependente da densidade, ao longo do estágio ontogenético. Finalizamos com a construção de um modelo hipotético acompanhado de predições testáveis sobre a distribuição espacial e dinâmica da espécie. Estes resultados atribuem à ação conjunta de processos bióticos e abióticos a possível resposta para complementarmos o entendimento sobre o padrão espacial encontrado, como já sugerido por outros estudos nos trópicos. / Several theories, including different factors and mechanisms, have been postulated to explain the high tree species coexistence in tropics, which remains an unsolved question that continues to pose a challenge to plant ecologists. Population-level tree dynamics studies contribute to a better understanding of the processes acting on community-level. The aim of the present study was to investigate some aspects related to the dynamics of a common tree species, Calophyllum brasiliense Camb. (Clusiaceae), in a Restinga Alta forest in Ilha do Cardoso, Cananéia, SP. We investigated if seedling survival and fitness were related to density-dependent herbivory, tested if the species presented an association with soil habitats and characterized its spatial patterns distribution in the study area. In General Introduction (Chapter 1) we enumerated the main theories developed so far to explain high tropical diversity, which include many processes acting on the tree species dynamics. Traditionally, models focused on density-dependent factors were frequently contrasted with models based on habitat or niche partitioning, but we know nowadays that both are acting simultaneously to determine community structure. For this reason we described in general lines both models. We also discussed how detected spatial patterns of a species may give account for underlying processes responsible for the generated patterns and the need of experimental tests after such inferences. Additionally, we resumed Janzen-Connell model which embases next chapter and was also the starting point of this dissertation. We did a brief contextualization about Janzen-Connell model and reviewed main results of investigations of its effects in others study areas using alternatives methodologies. As the next two chapters were developed in the same study area and with the same species, we also included their descriptions in the general introduction. In order to test the Janzen-Connell model (Chapter 2), we designed an experiment to evaluate C. brasiliense seedlings survival and fitness under three treatments: protection against herbivory, distance from conespecific adults and tree parental density. We found that the distance and density-dependent effects did not act as predicted by the model for our study species. Despite the high herbivory damages it suffered, its seedlings showed tolerance and compensatory growth responses. We proposed that pressure by host-specific herbivores seems to be widespread in the study area instead of aggregated around conespecific densities. Patterns detected also suggest that soil moisture is a better predictor for the species survival than herbivory. On chapter 3, therefore, we tested if density of this species presented any association with soil habitats, as suggested in chapter 2. We used an approach conjunct with the spatial distribution, permitting the inference of other underlying processes possibly related to the species dynamics besides the micro-habitat. We characterized the spatial distribution patterns using two complementary second-order point pattern statistics, K-Ripley and O-ring, and tested the habitat association using the torus translation procedure that incorporates spatial autocorrelation between conespecific stems. Besides detecting clumped distribution patterns, with variable critic scales with the analyzed size classes, we also detected a positive habitat association with temporally flooded soil (Neossolo), where its relative density was 30% greater comparing to others soils types. Adult stage was also positively associated with Neossolo and, in the other hand, was negatively associated with Espodossolo arênico, which is characterized by lower moisture soil levels. Young stage corresponded to only a quarter of all species stems and did not show any association with soils habitats. We suggest that flooding and anoxic conditions tolerance, as well as the occurrence of hidrocory among its dispersion types, the main factors favorable to survival and fast ontogenetic development in these soil conditions. We used information about C. brasiliense ecology from other studies to infer or exclude possible related factors with its spatial distribution and the habitat association and Janzen-Connell tests to complement these supposed factors. On Final Considerations we synthesize all proposed and tested information about underlying processes acting on C. brasiliense dynamics and suggest that the clumped spatial pattern detected may be an interaction result of three main factors: (1) differential association with both temporally flooded and unflooded soils, (2) occurrence of three simultaneous and complementary seed dispersal agents (gravity, bats and water) and (3) high density-dependent intra-specific competition through ontogenetic stages. We finalize proposing a hypothetic scenario with testable predictions about the species spatial pattern detected to C. brasiliense in the study area. These results attribute to grouping acting effects of both abiotic and biotic processes the possible answer to complement our understanding about tree spatial patterns founded, as suggested by other studies in the tropics.

O conhecimento dos mecanismos de pastejo dos equinos em pastos nativos é fator relevante para a melhor compreensão das relações dos animais com a complexidade da vegetação, possibilitando a otimização das funções ecossistêmicas e viabilização da criação. Com este propósito, foi avaliado por meio de monitoramento contínuo, o comportamento ingestivo de seis potros ao pé de éguas Crioulas, do nascimento aos 130 dias de idade, com intervalos 15 dias. Os animais foram divididos em duas manadas, manejadas em pastoreio contínuo, com oferta de forragem não-limitante, em pastagem natural do Bioma Pampa, região de Campos de solos rasos, Santana do Livramento, RS. Foram verificadas as relações e fatores de influência no aprendizado de pastejo do potro. O monitoramento contínuo por observação direta permitiu avaliar instantaneamente os bocados realizados pelos potros, durante quatro horas a partir do amanhecer, e quatro horas antes do anoitecer. Foram realizadas simulações de bocados para estimativa de MS de cada categoria de bocado e taxas de ingestão de MS instantânea dos animais. A composição e diversidade da dieta do potro em relação à mãe e aos pares demonstrou padrões de distanciamento que evidenciam funções definidas com a idade na evolução da herbivoria do potro. Verificaram-se duas fases bem definidas na evolução do pastejo do potro. A primeira fase exploratória, entre 0 e 60 dias, caracterizada pela grande diversidade de bocados e baixa ingestão de MS vegetal. Neste período, a base do aporte nutricional é via amamentação, e evidencia o maior distanciamento entre componentes da dieta de mãe e respectivo potro. O índice de diversidade da dieta do potro é maior que o índice de diversidade da vegetação, o que ratifica o caráter exploratório. A segunda fase, de especialização, inicia a partir dos 60 dias, onde ocorre uma especialização para a função ingestão de MS, preconizada pelo aumento na MS e diminuição na diversidade dos bocados. O grande aumento na ingestão de MS pelo potro entre 60 e 80 dias de vida denota um alinhamento das funções de égua e potro, com os padrões de composição da dieta semelhantes, se estabilizando ao redor de 100 dias. Entretanto, há diferenças entre as dietas dos grupos familiares (égua-potro), confererindo um fator cultural materno filial. A identificação dos períodos e fatores de aprendizagem do potro pode respaldar estratégias de manejo para melhor condução dos métodos de pastoreio dos equinos em ambientes pastoris, especialmente em pastagens naturais com grande biodiversidade, visando contemplar e ampliar funções ecossistêmicas. / Understanding the foraging mechanisms of horses in native pastures is a relevant factor for better comprehending the relationship of those animals in response to the vegetation complexity. It allows for optimizing ecosystem functions and livestock production. The ingestive behavior of six pairs of Criolo mares and foals was evaluated using continuous bite monitoring, from birth to 130 days, in 15 days intervals. The animals were divided in two groups, managed under continuous stocking, with non-limiting herbage allowance, in the shallow soil Pampa Grasslands, in southern Brazil. The relationships between and within pairs, and other influencing factors for the foraging learning process were assessed. The continuous monitoring allowed for evaluating bites for four hours after dawn and four hours before dusk. Bite simulations were done for estimating bite mass for each category, and calculating instantaneous dry matter intake rate. The diverging patterns of the foals’ diet composition and diversity in relation to their dams and to other peers indicated defined functions that varied with age in the evolution of herbivory. Two distinct phases were identified. First, an exploratory phase from 0 to 60 days, characterized by a great diversity of bites with low herbage intake and very distinct from the dam. During this period, milk is the main dietary component, and the diet (herbal) diversity index was larger than the diversity index for the vegetation. A second phase started at 60 days of age, where dry matter intake increased, by a specialization towards less diverse bites, but with higher mass. The large increase in dry matter intake between 60 and 80 days denoted an alignment of the intake functions of the mare and the foal, with similar diet composition, stabilizing at around 100 days. On the other hand, there was a difference on diet composition between family groups, indicating a cultural maternal filial influence. The identification of periods and factors affecting the foraging learning process of the foals can allow for improving pasture management strategies, especially on high-diversity, natural grasslands, contemplating and amplifying ecosystem functions.

Les plantes et les insectes forment l’un des principaux niveaux trophiques des écosystèmes au cours des 325 derniers millions d’années. Aujourd’hui, l’augmentation rapide et continuelle de la température principalement causée par l’activité humaine depuis les derniers siècles, perturbe la balance des écosystèmes sur Terre. En conséquence, comprendre le rôle des interactions entre les plantes et les insectes, à travers le temps mais aussi les réseaux trophiques, est essentiel. Le registre fossile est une opportunité exceptionnelle d’examiner les réponses aux interactions plante-insecte lors de longues variations climatiques et à travers des traces de réaction de la plante sachant que la Terre a déjà été soumise à de nombreux changements climatiques. Durant les derniers 3 millions d’années, des oscillations entre de longues périodes froides et de courtes périodes chaudes ont eu lieu. Les écosystèmes Européens ont particulièrement été impactés par ces oscillations. Le Langerstätte de Willershausen (Allemagne) a été particulièrement étudié. C’est un gisement contenant plus de 8000 feuilles fossiles. Ces feuilles relatent d’une paléoforêt ayant existé il y a 3- 2,6 Ma dans un climat plus chaud qu’aujourd’hui (ca.+5°C). Dans ces conditions climatiques, de nombreuses espèces d’écosystèmes Méditerranéens étaient présentes, telles que l’Érable de Montpellier ou l’Olivier. En comparaison, d’autres paléoforêts ont été prise en compte : Berga (du même âge et proche de Willershausen) et Bernasso (plus jeune que Willershausen (2,16 — 1,96 Ma) localisée dans le sud de la France près de la Méditerranée. Ces forêts sont comparables notamment du fait des nombreux taxons communs qu’elles partagent. En outre, certaines de ces espèces sont aujourd’hui endémiques de la région du Caucase, telles que le Parrotie de Perse ou encore l’orme du Caucase. Le but de cette étude a été de déterminer en quoi les différences climatiques peuvent être impliquées dans les changements des interactions plante-insecte au sein des paléoforêts Européennes de la fin du Pliocène - début du Pléistocène. Les résultats obtenus ont permis de mettre en évidence les impacts de la saisonnalité des températures et précipitations facteurs impactants les interactions plante-insecte des paléoforêts Européennes. Il est apparu que les écosystèmes sujets à d’intenses saisonnalités hydriques ont pu engendrer une plus grande spécialisation des interactions plante-insecte déduite d’un fort taux d’interactions spécialistes observées. En parallèle, les températures les plus froides durant l’année semble être un facteur important dans la faible diversité de dégâts, probablement dû à un faible métabolisme de la majorité des insectes. L’absence de corrélation convergente entre la richesse des plantes et la richesse des interactions pourrait suggérer que l’influence des facteurs climatiques surpasse l’impact potentiel des interactions biotiques locales. Pour l’ensemble de ces paramètres qui ont pu avoir un impact sur les interactions plante-insecte, nos connaissances actuelles sont encore insuffisantes. Il serait intéressant de focaliser davantage d’études sur les forêts modernes avec les méthodes appliquées dans le fossile. C’est dans cette intention qu’une partie de cette étude a étudié une espèce de plante (Parrotia persica) actuellement endémique de la forêt Hyrcanienne (Iran). Cette forêt est supposée être une forêt analogue des paléoforêts Européennes étudiées dans cette thèse. Pour le moment, les observations qui ont été faites en Iran semblent corroborer notre interprétation. Au final, les études sur les interactions plante-insecte des forêts anciennes et actuelles, combinés avec les études de changements climatiques, pourraient nous permettre de mieux caractériser les relations entre les insectes et les plantes au sein d’une forêt. / Insects are the most diverse animals on Earth, and neatly associated with plants they represent two of the major groups of organisms both in species diversity and biomass quantity. The majority of their interactions involves insect feeding and insect parasitism mostly on leaves. Plant and insect compose one of the main trophic levels in ecosystems over the 325 million years. Today, the continuous and fast rising of temperature mostly due to human activities since the last century is disturbing the balance of ecosystems on Earth. Consequently, to understand the role of plant and insect interactions, through time but also trophic networks, becomes crucial. The fossil record is an exceptional opportunity to survey responses of plant-insect interaction to climate variations over long time interval through traces of plants reactions caused by interaction with insects, as Earth has already experienced many climate changes. For the last 3 million years, oscillations between long cold periods and short warm periods have occurred. Europe ecosystems has been particularly impacted. The Lagerstätte of Willershausen (Germany) was specifically study. It is an exceptional fossil outcrop that contains ca. 8000 collected fossil leaves. These leaves testify a paleoforest developed there around 3—2.6 Ma ago in a climate warmer than today (ca. +5°C). Under these conditions, many plant species typical of the Mediterranean ecosystems were settled there, such as Montpellier maple or Olive tree. For comparison, other paleoforests were studied: Berga (similar in age and geographically close to Willershausen) and Bernasso (younger than Willershausen (2.16—1.96 Ma) and located in southern France close to Mediterranean. These forests were compared as many common plant taxa were similar between each other. Furthermore, some species today endemic to the Caucasian region, such as Persian ironwood or Caucasian elm, were also present in these outcrops. The aim of this study is to determine how far the climate differences could be involved in the changes of plant-insect interactions in European paleoforests of the late Pliocene – early Pleistocene. Results highlighted the impacts of both hydric and temperature seasonality, hitherto underestimated in the fossil record, on the patterns of plant-insect interaction in the European paleoforests. It appeared that ecosystems subject to intense hydric seasonality could led to higher specialization of plant-insect interaction inferred by higher rate of observed damages due to ‘specialists insects’. In parallel, the coolest temperature during the year seems to be a major factor in the low diversity of damage in paleoforest, presumably due to lower insect metabolism. Absence of convergent correlations between plant richness and damage richness could suggested that influence of climatic factors override impact of these local biotic factors. In order to understand the whole parameters that could have an impact on plant-insect interactions, our current knowledges are still insufficient. It would be wise to make more investigations on modern forests with the methods as applied in fossil record community structure studies. These investigations could help to understand the factors potentially involved in the establishment of a pattern of plant-insect interactions. It is in this perspective that a part of this study was precisely focused on one plant species (Parrotia persica) currently endemic to the Hyrcanian forest (Iran). This forest is supposed to be an analogue forest of the European paleoforests as those studied in this thesis. For now, observations made in Iran tend to corroborate our interpretation. Finally, the studies on plant-insect interactions in past and extant ecosystems, combined with the study of climatic changes, should permit us to better characterize the relations between plants and insects in forests through time.

<p>In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits, and population differentiation in the insect-pollinated, outcrossing, perennial herb <i>Arabidopsis lyrata</i>. More specifically, I (1) determined whether selection on flowering phenology and floral display can be attributed to interactions with pollinators and herbivores, (2) examined whether population differentiation in flowering phenology and floral display is correlated with current selection on these traits, and (3) tested for local adaptation from contrasting environments in Europe.</p><p>A field experiment conducted in a Swedish population demonstrated, that interactions with pollinators may markedly affect selection on both floral display and phenology of flowering. In an alpine population in Norway, grazing damage to inflorescences strongly influenced selection on floral display. The results suggest that variation in the abundance of pollinators and herbivores should contribute to spatio-temporal variation in selection on flowering phenology and floral display in <i>A. lyrata</i>. </p><p>A common-garden experiment showed that flowering phenology and floral display vary among Scandinavian populations of <i>A. lyrata</i>. For some traits patterns of population differentiation were consistent with differences in the direction and strength of phenotypic selection determined in comparisons (a) between an alpine population in Norway and a coastal population in Sweden, and (b) among coastal populations in Sweden. This suggests that current selection contributes to the maintenance of genetic differentiation in these traits.</p><p>Adaptive differentiation among populations was examined in a reciprocal transplant experiment that included populations from three contrasting environments, alpine Norway, coastal Sweden and lowland, continental Germany. The experiment provided evidence for local adaptation, and indicated that populations have diverged in traits affecting plant establishment and early growth.</p>

Biological invasions are an important issue of global change and an increased understanding of invasion processes is of crucial importance for both conservation managers and international trade. In this thesis, I have studied the invasion of the brown seaweed Fucus evanescens, to investigate the fate and effect of a perennial, habitat-forming seaweed introduced to a coastal ecosystem. A long-term study of the spread of F. evanescens in Öresund (southern Sweden) showed that the species was able to expand its range quickly during the first 20 years after the introduction, but that the expansion has been slow during the subsequent 30 years. Both in Öresund and in Skagerrak, the species is largely restricted to sites where native fucoids are scarce. Laboratory experiments showed that the restricted spread of F. evanescens cannot be explained by the investigated abiotic factors (wave exposure and salinity), although salinity restricts the species from spreading into the Baltic Sea. Neither did I find evidence for that herbivores or epibiota provide biotic resistance to the invader. On the contrary, F. evanescens was less consumed by native herbivores, both compared to the native fucoids and to F. evanescens populations in its native range, and little overgrown by epiphytes. Instead, the restricted spread may be due to competition from native seaweeds, probably by pre-occupation of space, and the establishment has probably been facilitated by disturbance. The studies provided little support for a general enemy release in introduced seaweeds. The low herbivore consumption of F. evanescens in Sweden could not be explained by release from specialist herbivores. Instead, high levels of chemical anti-herbivore defence metabolites (phlorotannins) could explain the pattern of herbivore preference for different fucoids. Likewise, the low epibiotic colonisation of F. evanescens plants could be explained by high resistance to epibiotic survival. This shows that colonisation of invading seaweeds by native herbivores and epibionts depends on properties of the invading species. The large differences between fucoid species in their quality as food and habitat for epibionts and herbivores imply that invasions of such habitat-forming species may have a considerable effect on a number of other species in shallow coastal areas. However, since F. evanescens did not exclude other fucoids in its new range, its effect on the recipient biota is probably small.

In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits, and population differentiation in the insect-pollinated, outcrossing, perennial herb Arabidopsis lyrata. More specifically, I (1) determined whether selection on flowering phenology and floral display can be attributed to interactions with pollinators and herbivores, (2) examined whether population differentiation in flowering phenology and floral display is correlated with current selection on these traits, and (3) tested for local adaptation from contrasting environments in Europe. A field experiment conducted in a Swedish population demonstrated, that interactions with pollinators may markedly affect selection on both floral display and phenology of flowering. In an alpine population in Norway, grazing damage to inflorescences strongly influenced selection on floral display. The results suggest that variation in the abundance of pollinators and herbivores should contribute to spatio-temporal variation in selection on flowering phenology and floral display in A. lyrata. A common-garden experiment showed that flowering phenology and floral display vary among Scandinavian populations of A. lyrata. For some traits patterns of population differentiation were consistent with differences in the direction and strength of phenotypic selection determined in comparisons (a) between an alpine population in Norway and a coastal population in Sweden, and (b) among coastal populations in Sweden. This suggests that current selection contributes to the maintenance of genetic differentiation in these traits. Adaptive differentiation among populations was examined in a reciprocal transplant experiment that included populations from three contrasting environments, alpine Norway, coastal Sweden and lowland, continental Germany. The experiment provided evidence for local adaptation, and indicated that populations have diverged in traits affecting plant establishment and early growth.

In this thesis, I examine variation in occurrence and performance of glabrous and trichome-producing plants of the perennial herb Arabidopsis lyrata. I combine field studies and genetic analysis to (1) examine the function of trichomes as a resistance character in natural populations, (2) compare the magnitude of population differentiation in trichome-production and at putatively neutral marker loci, (3) examine the molecular genetic basis of trichome-production, and (4) quantify the effects of herbivore removal on population growth and relative performance of glabrous and trichome-producing plants. In a survey of 30 populations of A. lyrata in Norway and Sweden, I documented spatiotemporal variation in damage from insect herbivores. With few exceptions, glabrous plants were more damaged by herbivorous insects than trichome-producing plants in polymorphic populations. Damage levels varied substantially among populations and among years. The intensity of herbivory quantified as mean leaf removal to glabrous plants was higher in polymorphic populations than in monomorphic glabrous populations. Within the Swedish range, populations were more strongly differentiated at the locus coding for glabrousness than at eight putatively neutral isozyme loci. This is consistent with the hypothesis that trichome production is subject to divergent selection. A study of the genetic basis of trichome production showed that glabrousness was associated with mutations in an orthologue to GLABROUS1, a regulatory gene known to cause glabrousness in A. thaliana. Comparative data indicate that the genetic basis of glabrousness varies among populations. Experimental removal of insect herbivores in a natural A. lyrata population increased population growth rate and the relative fitness of the glabrous morph. The results suggest that insect herbivory may influence both population dynamics and selection on trichome production in A. lyrata.

The strength and direction of interactions between organisms vary spatially across the landscape. Traditionally, the focus has been on how trait variation affects the interactions between species. However, differences in abiotic and biotic environmental factors may also alter the distribution, phenology and behavior of the interacting species. To be able to understand why an interaction varies across the landscape, the effects of trait variation has to be separated from the effects of the environmental context. In this thesis, I try to separate the effects of context and trait differences on plant resistance against herbivory, through experimental and observational studies conducted with two cytotypes of the perennial herb Cardamine pratensis and its main herbivore, Anthocharis cardamines. The results show that differences in plant resistance against oviposition under controlled conditions were mainly mediated by flower size; larger flowers were more attractive to the female butterfly. However, among-populations differences in oviposition under natural conditions were not related to the resistance observed under controlled conditions, or to ploidy type, flowering phenology or plant size. Within populations under natural conditions the oviposition patterns by A. cardamines was affected by the plant traits plant size and flowering phenology. The result of this thesis shows that among-population differences in intensity of plant-herbivore interactions were caused by differences in environmental context rather than by herbivore preferences for any phenotypic plant traits, while host plant selection within population was based on plant traits. This suggests that biotic and biotic context can have important effects on the intensity of plant-herbivore interactions. Although genetic traits influenced the outcome of the interaction within populations, it was the environmental context of the populations that determined largely if the interaction took place or not. / <p>At the time of the doctoral defence the following papers were unpublished and had  a status as follows: Paper 2: Manuscript in review in Plos One; Paper 3: Manuscript in review in <em></em>Ecological Entomology; Paper 4: Manuscript</p>