Studies assessing the evolution of plant traits frequently focus on pollinators as the primary drivers of floral trait evolution. However, herbivores can also play a role, and, under some circumstances, may even impose stronger selection on floral display than pollinators. This is especially true when the traits under selection are linked to anti-herbivore defense. Here I describe a study in which I quantified the relative role of herbivores and pollinators in selection for floral traits in the North American invasive plant, purple loosestrife (Lythrum salicaria). Because L. salicaria responds to leaf-chewing herbivores by producing compensatory tissue growth, and this in turn alters the architecture of the floral display, I further tested whether herbivores can indirectly modify pollinator-mediated selection through this pathway. Using a split-plot design, I measured pollen limitation and reproductive output in experimentally manipulated plants in the presence and absence of simulated herbivore damage in order to quantify the effects of damage and pollination on natural selection for floral display. My results showed that damage significantly increased direct selection (beta-i) for earlier flowering time and decreased selection on the number of inflorescences, even more than pollinators did. Because damage did not modify pollinator-mediated selection for floral display traits, the selection imposed by herbivores is likely only having direct effects. My findings demonstrate the importance of considering multiple agents of selection and their potential interactions when quantifying natural selection in a study system. In particular, it is important to consider that the agent most frequently studied may not be imposing the brunt of selection.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-10T14:45:01Z No. of bitstreams: 1 texto completo.pdf: 4890224 bytes, checksum: 1d08c6a269010cc1d2ffcc42cc47771f (MD5) / Made available in DSpace on 2015-11-10T14:45:01Z (GMT). No. of bitstreams: 1 texto completo.pdf: 4890224 bytes, checksum: 1d08c6a269010cc1d2ffcc42cc47771f (MD5) Previous issue date: 2014-02-25 / Fundação de Amparo à Pesquisa do Estado do Piauí / Banisteriopsis é considerado um dos gêneros mais complexos de Malpighiaceae devido à similaridade na morfologia floral, bem como ao elevado número de espécies, o que levou à proposição de diferentes tratamentos taxonômicos para circunscrição do gênero. A presença de glândulas calicinais e foliares é comum em Banisteriopsis e em vários representantes de Malpighiaceae, sendo consideradas estruturas importantes tanto para auxiliar na taxonomia quanto para o sucesso adaptativo da família. Com isso, este trabalho teve como objetivos descrever a anatomia foliar de 42 das 47 espécies de Banisteriopsis que ocorrem no Brasil; caracterizar anatomicamente as glândulas calicinais e foliares de 38 espécies; e identificar histoquimicamente a natureza química da substância secretada em B. campestris, B. laevifolia e B. malifolia. Foram identificados caracteres que auxiliaram na distinção de espécies, como: contorno do pecíolo, presença e ausência de feixes acessórios no pecíolo, conformação do sistema vascular do pecíolo, forma da nervura principal, presença e ausência de glândulas foliares, bem como a forma dessas estruturas. As glândulas calicinais diferem das foliares por apresentarem superfície secretora irregular, recoberta por cutícula espessa que se solta da epiderme pelo acúmulo da secreção. Nas demais características, as glândulas são semelhantes. Os testes histoquímicos detectaram grânulos proteicos, polissacarídeos e lipídios nas glândulas das espécies analisadas, evidenciando secreção de natureza mista. Este estudo comprovou a utilidade de dados anatômicos para os estudos de taxonomia em espécies de Banisteriopsis, indicando ser isso uma ferramenta promissora para a família Malpighiaceae como um todo. / Banisteriopsis is considered one of the most complex genera of Malpighiaceae due to similarity in floral morphology and the high number of species, which led to proposition of different taxonomic treatments for the circumscription of the genus. The presence of calycine and leaf glands is common in Banisteriopsis and several representatives of Malpighiaceae, both structures being considered important to assist in the taxonomy and to the adaptive success of the family. Thus the present study aimed to describe the leaf anatomy in 42 of the 47 species of Banisteriopsis occurring in Brazil; calycine anatomically characterize the gland 38 and leaf species and histochemically identified the chemical nature of the substance secreted in B. campestris, B. and B. laevifolia malifolia. Petiole outline, presence and absence of accessory bundles in the petiole, forming the vascular system of the petiole, midrib shape, presence or absence of foliar glands, as well as how these structures: characters who assisted in the distinction of species as identified. The calycine foliar glands differ by presenting irregular secretory surface, covered by a thick cuticle that loosens the epidermis by the buildup of secretions. All other features are similar glands. Histochemical tests detected protein granules, polysaccharides and lipids in the glands of the species analyzed, indicating secretion of mixed nature. The present study confirmed the utility of anatomical studies for taxonomy in species of Banisteriopsis data, indicating that this is a promising tool for the Malpighiaceae family as a whole.

Orientador: Simone de Pádua Teixeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-18T14:54:49Z (GMT). No. of bitstreams: 1 Basso-Alves_JoaoPaulo_M.pdf: 5360673 bytes, checksum: dcedc4cbe8765f92aca350ab0d6cfac5 (MD5) Previous issue date: 2011 / Resumo: A ausência de um dos verticilos reprodutivos em algumas flores pode decorrer da perda ou supressão de primórdios, o que pode ser elucidado por meio de estudos morfológicos do desenvolvimento floral. Ficus L. é um ótimo modelo para estes estudos, uma vez que possui representantes com sistemas sexuais diversos. Assim, o presente trabalho teve por objetivo comparar a morfologia da flor em desenvolvimento em Ficus citrifolia (monóica), F. hispida (ginodióica), F. racemosa (monóica secundária) e F. religiosa (monóica), a fim compreender as vias ontogenéticas que promovem a condição flor imperfeita. Para tal, sicônios em diversos estádios de desenvolvimento foram coletados, fixados em FAA 50, dissecados em lupa e preparados para observações de superfície em microscopia eletrônica de varredura (MEV) e histológicas em microscopia de luz. A organização dos meristemas florais e das flores no interior do sicônio é muito congesta na maioria das espécies estudadas, sendo menos acentuada em F. hispida (ginodióica). Diferenças no tempo de emergência dos meristemas e de alongamento do pedicelo em flores carpeladas foram observadas nas espécies monóicas (F. citrifolia, F. racemosa e F. religiosa) e parecem ser cruciais para a formação da heterostilia incompleta, típica de espécies monóicas deste gênero. As flores carpeladas de todas as espécies exibiram formação de sinestigma ao final do desenvolvimento (exceto aquelas do sicônio produtores de galha em F. hispida). Nossos dados, comparados aos de literatura, indicam que a ausência de estames nas flores carpeladas, tanto em espécies monóicas quanto em ginodióicas de Ficus, deve-se a um processo de perda, ou seja, os primórdios de estames não são iniciados no meristema floral. As flores estaminadas de F. hispida apresentaram supressão carpelar. A perda de primórdios estaminais é difundida no gênero e em Moraceae; já o carpelo pode ser perdido ou suprimido nestes grupos. Aspectos do desenvolvimento floral também são discutidos em relação à reprodução e biologia floral de Ficus / Abstract: The absence of reproductive organs in some flowers may ontogenetically arise by organ loss or suppression. Ficus L. is an interesting model for floral developmental studies, due to its diversity in sexual systems. The aim of this study was to compare the morphology of the floral development in Ficus citrifolia (monoecious), F. hispida (gynodioecious), F. racemosa (secondary monoecious) and F. religiosa (monoecious), to help understanding the ontogenetic pathways that promote the condition "imperfect flower". Thus, figs at various developmental stages were collected, fixed in FAA 50 and prepared for surface (scanning electron microscopy) and histological observations (light microscopy). The organization of the floral meristem and flowers inside the syconium is quite compressed, although F. hispida (gynodioecious) exhibits a less compressed floral arrangement inside the syconium. Variation in meristem inception time and pedicel elongation were observed in carpellate flowers of monoecious species (F. citrifolia, F. racemosa and F. religiosa) and should be crucial for establishment of incomplete heterostyly. The carpellate flowers of all species showed a sinstigma in the later developmental stages (except the gall-producing syconium in F. hispida). The staminate flowers of F. hispida showed carpel suppression. Our data, compared with those in the literature, indicate that the absence of stamens in carpellate flowers is due to loss of stamen primordium, both in gynodioecious and monoecious species. This condition is present in the genus and in Moraceae as a whole, while the carpel primordium may be lost or suppressed in this group. Aspects of floral development observed in Ficus are discussed in relation to their systematic and reproductive biology / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal

A podridão floral dos citros (PFC), causada por Colletotrichum acutatum, induz a abscisão de frutos jovens, podendo causar perdas de até 100%. A presença de inóculo viável na forma de conídios e/ou apressórios quiescentes na planta justifica a ocorrência generalizada da doença. Em períodos de chuva a PFC é agravada, possivelmente, em função de substâncias lavadas das diferentes partes da planta, as quais contêm metabólitos que estimulam o desenvolvimento do fungo. Diante do exposto, objetivou-se verificar o efeito das águas de lavagem brutas (ALBs) de flores, botões, folhas velhas (FV) e folhas novas (FN) e mistura destas sobre conídios, apressórios e hifas quiescentes de C. acutatum (isolados 61A e 142) in vitro e in vivo e sobre a severidade da PFC, bem como identificar substâncias presentes nas ALBs, exibindo a atividade biológica de interesse. Além disso, buscou-se verificar variações na composição das ALBs. O efeito de compostos voláteis brutos (CVBs) e os identificados a partir de laranjeira Valência (linalol, limoneno, mirceno, nonanal e a mistura destes) sobre o desenvolvimento do patógeno também foi avaliado. Todas as frações das ALBs estimularam a germinação dos conídios do fungo, sendo que a ALB de flores apresentou o maior estímulo para ambos os isolados. Para apressórios quiescentes (isolado 61A), o maior estímulo foi verificado nos tratamentos com ALBs de botões e da mistura e para conídios no tratamento mistura. Os maiores valores para comprimento do tubo germinativo foram observados nos tratamentos mistura, FN e botões. Para as estruturas quiescentes, o efeito das ALBs foi mais significativo para o isolado 142. Não foi observado efeito das ALBs sobre o micélio quiescente. Houve estímulo da germinação de conídios e ramificação de hifas in vivo, principalmente, em resposta ao tratamento com ALB de botões. A aplicação da ALB da mistura em flores resultou em maior severidade da PFC. Por sua vez, os CVBs apresentaram efeito inibitório. A exposição do isolado 61A aos voláteis (CVs) linalol, nonanal e mistura, resultou em germinação apenas na menor dose. O mirceno manteve a germinação semelhante a testemunha em todas as doses testadas, assim como limoneno nas doses de 0,005 a 0,25 µL mL-1. Todos os voláteis reduziram o comprimento do tubo germinativo. Para o isolado 142, houve redução em todas as variáveis para todas as doses dos CVs. Houve variações na composição das ALBs nas diferentes coletas, o que explica em parte a variação na capacidade de estímulo em alguns testes. Na ALB de flores, identificou-se a presença de cafeína, dos flavonóides glicosilados hesperidina e naringina, além de compostos glicosilados e peptídeos. Nas partes vegetais de laranjeira Valência foram identificados 54 CVs. As ALBs apresentam efeito estimulatório sobre conídios e apressórios quiescentes de C. acutatum in vitro e in vivo, bem como sobre a severidade da PFC. Os CVs linalol, limoneno, mirceno, nonanal e a mistura destes são, de forma geral, inibitórios ao desenvolvimento de C. acutatum. / The postbloom fruit drop of citrus (PFDC), caused by Colletotrichum acutatum, induces abscission of young fruits, and it may cause losses up to 100%. The presence of viable inoculum in the form of conidia and/or quiescent appressoria on the plant justifies the widespread occurrence of the disease. Under rain, the PFDC is increased, possibly due to substances washed from different parts of the plant, which contain metabolites that stimulate the development of the fungus. Therefore, we aimed to determine the effect of watery washing (WWs) of flowers, flower buds, old leaves (OL) and young leaves (YL) and the mixture of them on quiescent conidia and hyphae of C. acutatum (isolates 61A and 142) in vitro and in vivo and on the severity of the PFDC, and to identify substances in the WWs, exhibiting the biological activity of interest. In addition, variations in the composition of WWs were determinated. The effect of crude volatile compounds (CVCs) and those identified from Valencia sweet orange (linalool, limonene, myrcene, nonanal and the mixture of them) on the development of the pathogen was also evaluated. All fractions of WWs stimulated spore germination, and the flower WW exhibited the highest effect for both isolates. For quiescent appressoria (isolate 61A), the highest stimulus was observed in treatments with WWs from flower buds and the mixture and for quiescent conidia in the treatment mixture. The highest values for germ tube length were observed on the treatments mixture, YL and flower buds. For the quiescent structures, the effect of WWs was more significant for isolate 142. There was no effect of WWs on the quiescent mycelium. There was stimulation of conidia germination and hyphal branching in vivo in response mainly to treatment with WW from flower buds. The application of the mixture of WW in flowers resulted in higher severity of the PFDC. On the other hand, the CVCs showed inhibitory effect. Exposure of the isolate 61A to the volatiles (VCs) linalool, nonanal and the mixture of them, resulted in germination only at the lowest concentration. The germination on myrcene was similar to control at all doses tested as well as on limonene at doses from 0.005 to 0.25 mL mL-1. All volatiles reduced the length of the germ tube. In the case of isolate 142, a reduction in all variables for all concentration of VCs was observed. There were changes in the composition of WWs based upon times of harvesting, which partly explains the variations observed in the ability to stimulate the structures in some experiments. In flower WWs, we identified the presence of caffeine, the flavonol glycosides hesperidin and naringin, glycosylated compounds and peptides. In the plant parts of sweet orange \'Valencia\' were identified 54 VCs. The WWs have stimulatory effect on quiescent conidia and appressoria of C. acutatum in vitro and in vivo as well as in the severity of the PFDC. The VCs linalool, limonene, myrcene, nonanal and the mixture of them are, in general, inhibitory to the development of C. acutatum.

La transition florale résulte d’un jeu complexe d’interactions entre des signaux endogènes et environnementaux. Les feuilles jouent un rôle crucial dans ce processus en percevant les changements associés à la lumière et en produisant les photosynthétats qui participant à la signalisation de la floraison. Toutefois, notre connaissance des changements se produisant dans les feuilles lors de la transition florale reste limitée. Nous avons caractérisé les événements morphologiques, moléculaires et transcriptionnels en relation avec la floraison florale dans les feuilles matures chez Arabidopsis, en exploitant un système de transfert de conditions en jours courts vers des jours longs, transfert qui permet d’induire et synchroniser la floraison. Nous avons identifié la fenêtre temporelle de la transition florale, mesuré la croissance foliaire, et observé un accroissement de la ploïdie au cours du processus. Par une approche de RNA-seq, nous avons étudié la dynamique transcriptionnelle des réseaux de gènes dans la feuille, et comparé avec des données dans la racine et le méristème pour avoir une vue plus intégrée de la floraison dans la plante. De plus, nous avons analysé le mode d’action de LHP1 (LIKE HETEROPROTEIN 1), une sous unité du complexe PRC1, en exploitant des lignées transgéniques avec des modifications conditionnelles du dosage de LHP1 et en analysant les effets sur la chromatine et la transcription des gènes impliqués dans la floraison. Une modulation courte du dosage en LHP1 modifie le dépôt des marques H3K27me3 et H3K4me3, démontrant une interaction fonctionnelle entre LHP1 et le complexe PRC2, et suggérant aussi un nouveau rôle dans la formation de régions chromatiniennes de type bivalent. Enfin, étant donné le rôle clé de l’organisation nucléaire dans la régulation génique, nous avons recherché et identifié des déterminants de l’architecture nucléaire en utilisant de nouveaux outils de statistiques spatiales. / The transition to flowering results from a complex interplay between endogenous and environmental cues. The leaves play a key role in this process, by perceiving the light changes and producing photosynthates, which participate to the floral signalling. However, our knowledge on the changes occurring in leaves during floral transition is still limited. We characterised the morphological, molecular and transcriptional events related to floral transition in mature leaves in Arabidopsis, using a short-day to long-day shift to induce a synchronized flowering. We identified the temporal window of the floral transition, monitored the leaf growth and observed an increase in their ploidy level during the process. By RNA-seq we studied the transcriptional dynamics of the leaf gene network, and compared with events occurring in roots and meristems to get an integrated view of floral transition in the whole plant. Furthermore, we investigated the mode of action of LIKE HETEROPROTEIN 1 (LHP1), a PRC1 subunit, by exploiting transgenic lines with conditional alterations of LHP1 dosage and analysing the effects on chromatin and transcription of flowering genes. A short-term modulation of LHP1 dosage altered the deposition of H3K27me3 and H3K4me3, showing a functional interaction between LHP1 and PRC2, and also suggesting a new role in the formation of bivalent chromatin regions. Finally, since nuclear organisation plays a key role in gene regulation, we searched and identified determinants of the nuclear architecture by using innovative spatial statistical tools.

Previous studies of plant-pollinator interactions have relied on the use of floral visitation data. Although, this may be insufficient to fully characterize the diversity and strength of plant-pollinator interactions. By using pollen transport data (i.e. pollen on pollinators), new insights can be gained on the structure and function of plant-pollinator communities. Yet studies that characterize and compare pollen-transport with floral-visitation networks are scarce. Furthermore, the strength and frequency of plant-pollinator interactions can vary across temporal scales. Although, monthly and within-day variation in network structure has been little studied. By evaluating variation in network structure across these biologically relevant time scales we will gain a better understanding of the factors that shape plant-pollinator communities. Here, we build plant-pollinator interactions networks based on floral visitation and pollen transport data by observing, collecting and sampling pollen from floral visitors in a southern Appalachian floral community. We aim to 1) compare the congruence of plant-pollinator networks built on floral visitation and pollen transport data and 2) evaluate within season and within-day variation in plant-pollinator network structure. To assess floral visitation and to quantify pollen transport, four 1x40m transects were set up at the study site. Morning collections were conducted between 8:00 AM and 3:00 PM twice per week while afternoon collections took place once per week between 3:01 PM and 5:00 PM over 20 non-consecutive days. All flower visitors observed interacting with a flower’s reproductive structures (i.e. searching for pollen and nectar) were collected.All collected pollinators were processed for surface pollen loads by dabbing the body with a 3x3mm fuschin jelly cube. Each area of the body was dabbed three times to standardize sampling. Identification and quantification of pollen was done using a compound light microscope. Data was then analyzed with the “bipartite” package of R to create bipartite plant-pollinator networks. Procrustes analysis was used to identify differences in network structure. Preliminary results show that the structure of floral visitation and pollen transport networks are significantly different from each other (P <0.01). Pollen-transport network size is almost four times larger (496 links) compared to the floral-visitation network (109 links). Species in the pollen transport network tend to be more connected (connectance = 2.3) and have five times more links per species on average (5.22 links) than floral visitation networks (connectance = 1.1, links = 1.8). Within-season and within-day differences in network structure are currently being evaluated. Our results so far show that pollen transport networks at our study site captured 78% more unique interactions and, thus, provide more accurate network structure. Interpretation of pollen transfer versus floral visitation networks can have important implications for our understanding of community-level functions such as their resilience and stability.

Les Ranunculales sont un ordre d’angiospermes d’environ 4500 espèces, incluant des plantes communes comme les boutons d’or et les coquelicots. Leurs fleurs sont très diversifiées et ont piqué l’intérêt des botanistes depuis des décennies. Les sept familles de l’ordre sont faciles à reconnaître sur le terrain, mais paradoxalement, certaines familles n’ont pas de synapomorphies et ont des états ancestraux peu clairs, comme les Ranunculaceae (~ 2500 espèces). Cette diversité florale peut être liée à la pollinisation et des innovations ont pu être guidées par cette interaction. De plus, les plantes de ce groupe produisent une grande variété de composés secondaires, certains dont les propriétés sont connues depuis fort longtemps (comme la morphine et le curare). Ces substances pourraient jouer un rôle dans la défense contre les herbivores. Les caractères floraux et chimiques sont donc de bons candidats pour produire des hypothèses adaptatives. Ici nous utilisons des méthodes analytiques modernes pour comprendre les patrons d’évolution expliquant la distribution actuelle de la diversité et l’évolution des fleurs et des toxines de Ranunculales. Un nouveau cadre phylogénétique synthétique a été produit avec des séquences publiées de 144 espèces. Seize caractères floraux et la présence de certains composés métaboliques ont été reconstruits sur cet arbre avec la méthode de parcimonie et la méthode de « Reversible Jump Monte Carlo Markov Chains ». Un nouveau scénario d’évolution florale a été produit, où les Ranunculales avaient une fleur ancestrale trimère avec trois cycles de tépales et où les ancêtres des familles ont évolué en perdant ou en différenciant des cycles du périanthe. Les patrons d’évolution des toxines montrent de la variabilité, certaines apparaissant et disparaissant aléatoirement (comme les saponines), d’autres étant des synapomorphies bien soutenues de certains clades (comme les diterpènes de type aconitine pour la tribu des Delphinieae). Ces résultats offrent une meilleure compréhension de l’histoire naturelle des Ranunculales. En outre, cet ordre est le groupe-frère de toutes les autres eudicotylédones, et a donc une position clef pour comprendre l’évolution précoce de ce clade. Ces résultats vont fournir une compréhension plus profonde des changements floraux et phytochimiques qui ont eu lieu à la base des eudicotylédones, qui contiennent 70% des angiospermes actuelles. / Ranunculales are an order of angiosperms comprising ca. 4,500 species including common plants like buttercups and poppies. Their flowers are highly diversified and have raised the interest of botanists for decades. Each of the seven families of the order is easily recognizable in the field, but paradoxically some families lack floral synapomorphies and have unclear ancestral states, like Ranunculaceae (ca. 2,500 species). This floral diversity may be linked to pollination and innovations may have been driven by this interaction. In addition, the plants of this group produce a variety of secondary compounds, some of which having been known for ages for their properties, like morphine or curare. Those substances could play a role in defense against herbivores. Both floral and chemical characters are thus good candidates to produce adaptive hypotheses. Here we used modern analytical methods to understand the the evolutionary patterns accounting for the extant distribution of diversity and evolution of Ranunculales flowers and toxins. A new synthetic phylogenetic framework of the Ranunculales based on already available sequences of 144 species was produced. Sixteen characters of the flower, and the presence of selected secondary metabolites were reconstructed on this tree using parsimony, and Reversible Jump Monte Carlo Markov Chains. A new scenario for floral evolution was produced, where Ranunculales had a trimerous perianth with three whorls of tepals ancestor, and the ancestors of the families evolved by losing and/or differentiating perianth whorls. The evolutionary patterns of toxins showed variability, some appearing and disappearing randomly (such as saponins), others being well-supported synapomorphies (such as aconitine-like diterpens for the tribe Delphinieae). These results offer a better understanding of the natural history of Ranunculales. Furthermore, this order is the sister-group of all other eudicots, and thus has a key position to understand the early evolution of this clade. These results will provide a deeper understanding of the floral and chemical changes that took place at the base of eudicots, which contains 70% of living angiosperms.

L'expansion des surfaces urbaines a de fortes conséquences sur la composition des communautés de plantes et de pollinisateurs. Néanmoins, les effets de l'urbanisation sur l’interdépendance entre ces deux communautés et leurs conséquences évolutives restent peu étudiés. Premièrement, nous avons cherché à identifier le long d'un gradient d'urbanisation les facteurs affectant les communautés de plantes et de pollinisateurs. Deuxièmement, nous avons testé l'existence de divergences évolutives intra-spécifiques pour les caractéristiques reproductives de plantes d'origine urbaine et rurale. Dans ce but, nous avons combiné l'analyse de données issues de programmes de sciences participatives en région de l'Ile-de-France et nous avons également mis en place une expérience de transplantation réciproque impliquant quatre espèces végétales fréquentes dans cette région. Nos résultats révèlent que la morphologie florale est le facteur le plus souvent impliqué dans l'observation des familles d'insectes sur les fleurs le long du gradient. Les familles d'insectes ayant une affinité positive aux surfaces imperméables préfèrent les corolles tubulaires, tandis que les familles ayant une affinité négative préfèrent les corolles évasées. L'urbanisation modifie la composition des communautés végétales, en sélectionnant notamment des espèces autogames et non-entomophiles. Nos résultats indiquent une perte fonctionnelle de pollinisateurs en milieu urbain. Une analyse détaillée de l’espèce Cymbalaria muralis suggère que les plantes auraient un plus grand bénéfice reproductif à allouer plus de ressources à la production de fleurs sur les sites de plantation urbain. En conséquence, les plantes d'origine urbaine ont tendance à produire plus de fleurs que celles d’origine rurale, au détriment de la production d'ovules par fleur et de la coloration des corolles. Cette divergence évolutive pourrait s'expliquer par des changements dans le comportement des pollinisateurs induits par une fragmentation accrue de l'habitat dans les zones urbaines. Cette thèse révèle que les changements induits par l'urbanisation dans l'abondance, le comportement ou les affinités florales fonctionnelles des pollinisateurs peuvent servir d'agents de sélection sur les espèces végétales spontanées. / The expansion of urban areas is known to impact the composition of plant and pollinator communities. However, the effects of urbanization on the interdependency between both communities, and the subsequent evolutionary consequences, are still poorly studied. First, we tried to identify along an urbanization gradient which factors shape plant and pollinator communities. Second, we tested the existence of intra-specific evolutionary divergences of plant reproductive characteristics between populations from urban and rural origins. For these purposes, we combined the analysis of data collected in the Ile-de-France region originating from citizen science projects, and we set up a reciprocal transplantation experiment involving four plant species commonly found in this region. We found that floral morphology was the most frequently implicated factor in the observation of insect families along the gradient. Insect families with positive affinity to impervious areas prefer tubular corollas, while families with negative affinity prefer non-tubular (open) corollas. Urbanization modifies the composition of plant communities, by selecting in particular autogamous and non-entomophilous species. Altogether, our results point towards a functional loss of pollinators along with urbanization. A detailed analysis of the species Cymbalaria muralis suggests a greater reproductive benefit in allocating more resources to flower production in urban plantation sites. As a consequence, plants from urban origin tend to produce more flowers compared to plants from rural origin, at the expense of ovule production per flower and flower coloration. This evolutionary divergence could be explained by shifts in pollinator behaviour induced by higher habitat fragmentation in urban areas. This thesis reveals that shifts in the abundance, in the behaviour or in the functional floral affinities of pollinators, induced by urbanization, could act as selection agents on spontaneous plant species.

Functional traits, particularly those that impact fitness, can shape the ecological and evolutionary relationships among coexisting species of the same trophic level. Thus, examining these traits and properties of their distributions (underdispersion, overdispersion) within communities can provide insights into key ecological interactions (e.g., competition, facilitation) involved in community assembly. For instance, the distribution of floral colors in a community may reflect pollinator-mediated interactions between sympatric plant species, and the phylogenetic distribution of color can inform how evolutionary contingencies can continue to shape extant community assemblages. Additionally, the abundance and species richness of the local habitat may influence the type or strength of ecological interactions among co-occurring species. To evaluate the impact of community size and species richness on mechanisms shaping the distribution of ecologically relevant traits, we examined how floral color (defined by pollinator color vision models) is distributed within co-flowering assemblages. We modeled floral reflectance spectra of 55 co-flowering species using honeybee (Apis mellifera) and syrphid fly (Eristalis tenax) visual systems to assess the distributions of flower color across 14 serpentine seep communities in California. We found that phylogenetic relatedness had little impact on the observed color assemblages. However, smaller seep communities with lower species richness were more overdispersed for flower color than larger, more species-rich communities. Results support that competitive exclusion could be a dominant process shaping the species richness of flower color in smaller-sized communities with lower species richness, but this is less detectable or overwhelmed by other processes at larger, more speciose communities.

This study examines the effects of clearcut regeneration with whole-tree harvesting on plant diversity. Three approaches were used to study changes in species composition and structure: (1) forest level, (2) stand level, and (3) diversity indices. Within each approach the forest was stratified into three horizontal vegetative regions based upon height: herb (< 1 m), shrub (between 1 and 5 m), and tree (> 5 m). Between the pre-harvest and 17-year-old forest, the relative percent cover of 3 out of 45 herbaceous and 2 out of 34 woody species were found to be significantly different (df = 3; a = 0.10) in the herb stratum; the importance value (average of relative basal area and stem density) of 2 out of 25 woody species in the shrub stratum; and 1 out of 21 woody species in the tree stratum. Within stands, the three lower quality, 17-year-old stands (SI50 = 12.2, 15.2, and 18.3 m) most resembled their pre-harvest composition; however, increases in ericaceous species were observed in the herb and shrub strata potentially inhibit the future regeneration of tree species. The SI50 = 21.3 m stand incurred the greatest changes in composition potentially due to the lack of fire as a disturbance mechanism. The major mechanism that has caused the shifts in species composition and structure is the change in the microenvironment due to the removal of the overstory, which has shifted the competitive advantages from one species to another. In all cases, diversity indices were not found to be significantly different between the 17-year-old and pre-harvest forests. Diversity indices were therefore determined to have limited use if a manager wants to know specific compositions and/or abundance of species. / Master of Science