Dissertations / Theses on the topic 'Angiosperms'
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Marlowe, Karol. "Biogeography and evolution of flowering plants in the American West : Gaillardia (asteraceae) and Synthyris (plantaginaceae)." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Spring2007/k_marlowe_043007.pdf.
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Yu, Boying. "Gametogenesis and flower development controlled by AtAnamorsin1 and AtPUB4." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/158.
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Flowers are the organs for sexual reproduction in angiosperms. Gametogenesis in floral organs leads to formation of sperms and eggs and their fertilization forms a zygote that develops into a new plant. Gametogenesis and embryogenesis involve precisely regulated biological processes controlled by complex networks of genes and pathways. In this study, AtANA1, which was identified as a redox sensitive protein in previous study, was found to be essential for embryogenesis and also plays an important role in both male and female gametogenesis. Without a functional AtANA1, embryo development is arrested after the first cell division of the zygote. The ana1 mutation also causes arrest in different steps of male and female gametogenesis. Aborting pollen and embryos caused by the ana1 mutation exhibit enhanced accumulation of reactive oxygen species and DNA fragmentation, marks of programmed cell death. Presence of aborting ana1 pollen was also found to lead to abortion of wild type pollen in the same anther, raising a possibility that the aborting ana1 pollen might release a death signal. ANA1 could be involved in an oxidative stress signaling pathway, and loss of its function triggers death of gametophytic and embryonic cells. Another important protein involved in Arabidopsis reproductive processes is PUB4, an E3 ubiquitin ligase. The pub4 mutation was previously found to cause abnormal enlargement of tapetal cells and incomplete degeneration of the tapetum layer, resulting in a defect in pollen release and conditional male sterility. In this study, we characterized PUB4’s role in controlling floral meristem determinacy. The pub4 mutation causes formation of ectopic floral organs inside of carpels/siliques. It was found that the pub4 mutation leads to ectopic expression of WUSCHEL, an important regulator which is essential for maintaining shoot apical meristem and floral meristem, which could be responsible for the flower-in-flower phenotype. PUB4 appears to work additively with AGAMOUS (AG) to control appropriate expression of the WUS gene. Three extra large G proteins (XLGs) in Arabidopsis, which interact with PUB4, also play roles in controlling tapetal cell enlargement and degeneration. However, XLGs might not function in floral meristem determinacy.
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Lee, Alexandra P. "CO2 decline and the rise of the angiosperms." Thesis, University of Nottingham, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716841.
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The angiosperms (flowering plants) occupy almost every habitat type on Earth and comprise nearly 90% of extant plant species. Yet this dominance is a relatively recent (geological) occurrence as they have a late evolutionary origin (-140 Ma). The Cretaceous angiosperm radiation to dominance temporally coincides with a time of atmospheric CO2 ([CO2]) decline and detrimentally impacted pteridophyte and cycad diversity in the understorey and gymnosperm diversity in the canopy. The first objective of this thesis was to investigate [CO2] decline as a trigger for the rise of the angiosperms. Six species were grown at modern ambient and three elevated levels of [CO2] (800, 1200 and 2000 ppm), which corresponded to Cretaceous concentrations. The comparative ability of these species to acclimate physiologically, morphologically and biochemically were used as a model for Cretaceous plant groups. Ranunculus acrls and Polypodium vulgare, were chosen to represent Cretaceous understorey angiosperms and pteridophytes respectively. Liquidambar styraciflua and Laurus nobills represented canopy angiosperms and Ginkgo biloba and Metasequoia glyptostroboides canopy gymnosperms.
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Reyes, Elisabeth. "Evolutionary history of floral key innovations in angiosperms." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS489/document.
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Les Angiospermes forment un clade connu pour sa grande diversité d’espèces et une répartition inégale de cette diversité en son sein. Ce travail se concentre sur la reconstruction d’états ancestraux de caractères floraux sur les phylogénies dans le but d’étudier leur impact sur la diversification. En premier lieu, nous nous sommes focalisés sur deux innovations-clés potentielles chez les Proteaceae, la symétrie bilatérale du périanthe et la présence dans les hotspots à climat méditerranéen. L’utilisation sur une phylogénie de modèles de diversification dépendants des états de caractère a permis de montrer que le premier état caractère n’a pas d’impact significatif sur la diversification des espèces dans ce groupe, contrairement au second. Ensuite, nous avons reconstruit les états ancestraux de la symétrie du périanthe à l’échelle de toutes les Angiospermes, avec une stratégie d’échantillonnage permettant de refléter toutes les transitions de ce caractère. Nous avons mis en évidence un minimum de 130 origines de la symétrie bilatérale, suivies de 69 réversions vers la symétrie radiaire. Enfin, la même méthode a été étendue à l’étude de quatre autres caractères du périanthe. Différents modèles de reconstruction d’états ancestraux ont été utilisés sur une phylogénie de 1232 espèces pour examiner l’influence des changements de modèle sur les états ancestraux reconstruits. Nos résultats montrent que les changements de modèles de reconstruction ont une influence sur l’état de certains nœuds seulement, jamais sur l’ensemble. Les différents résultats trouvés pour la symétrie, caractère commun aux trois chapitres, révèlent que notre méthode d’échantillonnage présente l’inconvénient d’estimer des taux de transition trop élevés pour donner des résultats concluants avec la méthode du maximum de vraisemblance. Les résultats sont en revanche beaucoup moins biaisés lorsque l’on examine plusieurs caractères simultanémentAngiosperms are a clade known for its great species diversity and the uneven distribution of this diversity among its lineages. This work focuses on the ancestral state reconstruction of floral characters on phylogenies in the purpose of studying their impact on diversification. We first focused on two potential key innovations in Proteaceae, bilateral perianth symmetry and presence in Mediterranean-climate hotspots. Using character state dependent diversification models, we found that the first character state did not have any significant impact on species diversification in this group, contrary to the second one. We then reconstructed ancestral states for perianth symmetry in angiosperms as a whole, using a sampling strategy aimed at capturing all of the transitions in this character. We found a minimum of 130 origins of bilateral symmetry, followed by 69 subsequent reversals to radial symmetry. Lastly, the same approach was extended to the study of four other perianth characters. Different ancestral state reconstruction models were used on a phylogenetic tree of 1232 species to test the influence of model changes on reconstructed ancestral states. Our results show that changes in reconstruction models have an impact on the inferred ancestral state of some nodes, but not all of them. The various results obtained for symmetry, a character shared among the three chapters, indicate that our sampling method has the drawback of estimating transition rates too high to give conclusive results with maximum likelihood. On the other hand, results are much less biased when several characters are examined simultaneously
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Branco, Diana Santos 1983. "Sinalização por carboidratos em cana-de-açucar e divergencia evolutiva." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317165.
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Orientadores: Michel Georges Albert Vincentz, Juliana de Maria FelixDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-11T18:43:41Z (GMT). No. of bitstreams: 1 Branco_DianaSantos_M.pdf: 18385613 bytes, checksum: 43238e785391538d38599321de0ac5ca (MD5) Previous issue date: 2008
Resumo:Além de fonte primária de carbono e energia para os principais tipos celulares, os açúcares produzidos pela fotossíntese adquiriram importantes funções ao longo da evolução das plantas, no controle do crescimento e desenvolvimento, do metabolismo e na resistência a estresses abióticos (osmótico, energético) e bióticos (potógenos). Os açúcares atuam como sinalizadores ativando cascatas de transdução e, desta forma, promovendo mudanças na programação da expressão gênica. Com o objetivo de entendermos como a sinalização por açúcares diversificou-se em angiospermas, iniciamos uma análise comparativa dos perfis de expressão gênica em resposta aos açúcares sacarose e glicose em plântulas da monocotiledônea Saccharum spp e da eudicotiledônea Arabidopsis thaliana. Para tanto, duas abordagens foram utilizadas. O primeiro aspecto do trabalho estabeleceu relações entre elementos de resposta rápida (resposta primária) a açúcar e acúmulo de sacarose em genótipos de cana contrastantes para teor de sacarose. Outra abordagem, mais abrangente, procurou identificar genes diferencialmente expressos em resposta à sacarose. Na primeira parte do trabalho, a análises por qRT-PCR revelaram uma clara relação entre genes envolvidos em acúmulo de sacarose em cana-de-açúcar e sinalização primária por carboidratos. A partir de 34 SAS (Sugarcane Assembled Sequence) testados envolvidos em acúmulo de sacarose em cana, 24 deles também foram responsivos à glicose e/ou sacarose, sendo que 9 deles responderam em um mesmo sentido em genótipos de cana-de-açúcar que acumulam maior quantidade de sacarose (alto Brix). Dos 24 SAS responsivos à sacarose e/ou glicose, apenas 6 deles apresentaram genes ortólogos em Arabidopsis thaliana cuja regulação por estes açúcares ocorreu de maneira similar. Dentre eles, temos o fator de transcrição IAA16, que se mostrou reprimido por sacarose e glicose, constituindo um possível gene de interação entre sinalização por açúcares e auxina. Duas SNFs quinases parálogas de cana-de-açúcar tem como ortólogo um único gene de Arabidopsis thaliana. Os três genes foram reprimidos por sacarose e glicose, sendo outra parte conservada, na via de sinalização a açúcares entre as duas espécies. Outro gene de particular interesse corresponde a uma deidrina, reprimida por sacarose e glicose em cana, assim como seu ortólogo em Arabidopsis e genótipos alto Brix, sugerindo importante papel deste gene em processos relacionados a sinalização/acúmulo de sacarose. Na segunda parte do trabalho, utilizando-se a técnica de microarranjos de cDNA a partir do chip SUCAST, encontramos 55 genes diferencialmente expressos em resposta à sacarose. Destes, apenas 3 apresentaram genes ortólogos de Arabidopsis regulados por açúcar num mesmo sentido que em cana, correspondentes a duas proteínas quinases e a um gene pseudo-response-regulator. Este estudo preliminar identificou genes conservados da sinalização por açúcares em angiospermas que representam possíveis nós importantes das redes de controle relacionadas a carboidratos. O estabelecimento de um possível envolvimento de alguns destes genes no controle da capacidade de acumular mais sacarose no colmo da cana, abriu novas perspectivas na análise molecular desta importante característica. Estudos mais abrangentes são necessários para melhorar os conhecimentos sobre o grau de diversificação da sinalização por açúcares em angiospermas e os valores adaptativos associados.
Abstract: Besides act as carbon primary source in the major types of cells, sugars produced by photosynthesis acquired important functions in the course of plant's evolution like controlling growth, development, and metabolism and acting in resistance to abiotic and biotic stresses like osmotic, energetic and response to pathogens. Sugars can be signals that active signal transduction pathways to change genes expression programs. In order to access the diversification of sugar pathway signaling in angiosperms we conduct comparative analysis of the gene expression in response to sucrose and glucose in seedlings of the monocot Saccharum sp. and the eudicot Arabidopsis thaliana. We also aimed to access the possible correlation between genes related to sucrose storage in sugar-cane and genes related to primary sugar responses. Another aim was to identify deferentially expressed genes in sucrose response. A clearly relation between genes related to sucrose storage in sugar-cane and quickly primary response to sugars was obtained by qRT-PCR analysis. We tested 34 SAS (Sugar Assembled Sequence) related to sucrose storage in sugar-cane and we found that 24 of them were responsive to glucose and/or sucrose. Nine genes showed the same expression pattern (induction or repression) in response to sugar as seen in high Brix genotypes. Six, of this 24 genes, have Arabidopsis orthologues regulated in the same direction (induced or repressed). One is an IAA16 transcription factor that is repressed by both, glucose and sucrose, and may play a role in an integrative pathway of sugar and auxin responses. We also find two SNFs kinases (paralogues) related to a single Arabidopsis ortholog showing the repression response. Another interesting gene is a dehydrin that was repressed in response to sucrose and glucose in sugar-cane and Arabidopsis (its ortholog) and in the high Brix sugar-cane genotypes. It suggests an important role for this dehydrin in processes related to sucrose signaling and storage. In the second part of this work, the sugar-cane cDNA microarray chip, called SUCAST, allow us to identify 55 deferentially expressed in response to sucrose. Only three of these genes have orthologues regulated in same way in sugar-cane and Arabidopsis. These genes correspond to two protein-kinase and a pseudo-response regulator. This preliminary approach leads us to identify conserved genes in sugar signaling among angiosperms that possibly represents important nodes in the regulatory networks in response to sugars. Establishing the involvement of some of these genes in the ability of sucrose storage in sugar-cane's culm will lead us to new perspectives in the molecular basis of this characteristic. More specific works are also needed to improve the knowledge about the real degree of evolutive diversification in sugar signaling among angiosperms and associated genetic fitness.
Mestrado
Genetica Vegetal e Melhoramento
Mestre em Genética e Biologia Molecular
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Martins, Aline Cristina. "Abelhas coletoras de óleo e suas interações com as flores de Plantaginaceae produtoras de óleo floral." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/59/59131/tde-23042010-154006/.
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Os óleos florais são os recursos alternativos ao pólen e néctar oferecidos por onze famílias de angiospermas às abelhas coletoras de óleo. A produção deste recurso surgiu ao menos 28 vezes e a coleta destes, em cinco linhagens distintas entre as abelhas. Na região Neotropical, Malpighiaceae é a família mais diversa e melhor conhecida em termos de seu sistema de polinização e relação com abelhas coletoras de óleo. Plantaginaceae é conhecida por alguns trabalhos, focados principalmente em Angelonia e Monttea. No presente estudo, são apresentadas as relações entre abelhas coletoras de óleo e flores de Plantaginaceae (cinco espécies de Angelonia e uma de Basistemon), com especial atenção aos aspectos morfológicos de ambos, aspectos comportamentais das abelhas durante a coleta e a sobreposição geográfica entre os parceiros deste mutualismo. Este trabalho apresenta pela primeira vez dados dos visitantes de três espécies: A. eriostachys, A. goyazensis e Basistemon silvaticus; além de dados inéditos sobre espécies já estudadas: A. cornigera, A. integerrima e A. salicariifolia. Foi observado que as estruturas especializadas presentes no labelo de todas as espécies estudadas de Angelonia estão associadas à imposição da postura correta do visitante e sua fixação na flor. As flores de Basistemon são mais simples neste sentido e apresentam apenas um discreto calo mediano. Apesar da morfologia destas estruturas diferirem consideravelmente entre as espécies, é possível estabelecer relações de origem entre elas. A assembléia de visitantes das flores de Angelonia e Basistemon variou entre três a dezoito espécies. Estas espécies foram consideradas polinizadoras ou visitantes ilegítimos. As abelhas do gênero Centris foram consideradas as principais polinizadoras das plantas estudadas, porém, espécies de Tapinotaspidini, em especial o gênero Caenonomada, também detêm esse papel. As abelhas que coletam óleo também coletam pólen, com exceção dos gêneros Centris, Caenonomada e Tapinotaspis, que coletam apenas óleo. O comportamento adequado dos polinizadores de Angelonia e Basistemon, imposto pela morfologia floral, implica na coleta do óleo com as pernas anteriores e o contato com os órgãos férteis na fronte ou mesoscuto em flores com corola mais profunda. Algumas espécies estão morfologicamente adaptadas a coleta nestas flores, como exemplo, as abelhas Centris grupo hyptidis, que possuem aparatos coletores divergentes de todo o padrão apresentado pelo gênero. Quanto à distribuição destas plantas e de seus potenciais polinizadores, em alguns casos, há grande sobreposição e os potenciais polinizadores podem ou não ser especialistas nestas fontes de óleo. Os casos de baixa congruência geográfica mostram que muitos destes potenciais polinizadores não dependem das fontes de óleo de Angelonia e Basistemon.Floral oils are alternative flower reward to pollen and nectar that are offered by eleven families of angiosperms to oil-collecting bees. The production of this resource appeared at least 28 times, and its collection has been observed in five different lineages of bees. In the Neotropical Region, Malpighiaceae is the most diverse and best known family concerning to the pollination system and the interactions with oil-collecting bees. Plantaginaceae is well known due to some studies mostly on Angelonia and Monttea. In this study, the relationship between the oil-collecting bees and the Plantaginaceae flowers (five species of Angelonia and one of Basistemon) is presented, being given special attention to the morphological aspects of both, the bees behavior during the oil collection and the geographical overlap between the partners of this mutualism. This work presents for the first time the visitors of three species (A. eriostachys, A. goyazensis and Basistemon silvaticus), as well as new data on already studied species (A. cornigera, A. integerrima and A. salicariifolia). It was recorded that the specialized structures that are found on the lip (labellum) of all the known species of Angelonia are associated to the imposition of the correct posture of the visitor and their fixation on the flower. The Basistemon flowers are, in this way, less complex and they present only a discrete median callus. Although the morphology of these structures differ considerably among species, it is possible to establish relationships between their origins. The assemblage of visitors of the flowers of Angelonia and Basistemon varied from three to eighteen species. These species were considered pollinators or illegitimate visitors of the studied species. The bees of the genus Centris were considered the main pollinators of these plants; however species of Tapinotaspidini also play this role. These bees collect oil and pollen, in most species, having as exceptions the genera Centris, Caenonomada e Tapinotaspis that collect only oil. The correct behavior of the visitors of Angelonia and Basistemon flowers, imposed by the floral morphology, results the collection of oil with the forelegs and the contact of their fertile organs with their anterior head or dorsal thorax (in flowers with deep corolla). Some species are morphologically adapted to sample in these flowers, for example, the Centris bees group hyptidis, that have collecting apparatus that diverge from the pattern found in the genera. In respect to the distribution of these plants and their potential pollinators, in some cases, there is a large overlap and the potential pollinators may or may not be specialists in these oil sources. The cases of low geographical congruency show that many of these potential pollinators do not depend only on the oil sources of Angelonia and Basistemon.
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Behera, Jyoti, and Aruna Kilaru. "Comparative in Silico Analysis of WRINKLED1 Paralogs in Angiosperms." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/7723.
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Behera, Jyoti, Shina Bhatia, and Aruna Kilaru. "Comparative in Silico Analysis of WRINKLED1 Paralogs in Angiosperms." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/7724.
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WRINKLED 1(WRI1), a member of AP2/EREBP class of transcription factors regulates carbon allocation between glycolytic and fatty acid biosynthetic pathway. Additionally, among the four WRI1 paralogs in Arabidopsis, WRI3 and 4 but not WRI2, are also able to increase fatty acid content in different tissues. While the role of WRI1 is well established in seeds, the potential or WRI1 or its paralogs as master regulators in oilrich nonseed tissues is poorly understood. Recent transcriptome studies of avocado (Persea americana) mesocarp revealed that the ortholog of WRI2, along with WRI1 and WRI3 was highly expressed during oil accumulation.Through transient expression assays, wefurther demonstrated thatbothPaWRI1 andPaWRI2 can accumulate oil in tobacco leaves. We conducted a comprehensive and comparative in silico analysis of WRI paralogs from a dicot, monocot and a basal angiosperm to identify distinct features associated with function. These data provide insights into the possible evolutionary changes in WRI1 homologs and allow for identification of new targets to enhance oil biosynthesis in diverse tissues.
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Fagundes, Paula Braga. "Um lugar ao sol : a influência do fator histórico sobre o nicho de luz e respostas ecofisiológicas de plantas com semente da floresta ombrófila mista." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/90470.
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Em ambientes florestais, a luz é o recurso que com mais frequência limita o crescimento, a sobrevivência e a reprodução em plantas. Assim, a variação na disponibilidade de luz no sub-bosque influencia a composição local de espécies lenhosas, que se segregam em diferentes nichos de luz de acordo com suas preferências e tolerâncias, conferidas através de suas adaptações e plasticidade fenotípica. Os atributos das espécies atuais, além de serem adaptados ao ambiente onde vivem, são um legado de seus ancestrais, motivo pelo qual espécies mais próximas filogeneticamente, com frequência compartilham atributos semelhantes e, por consequência, ocupam nichos similares, padrão conhecido como conservação filogenética. Estudos recentes mostram que atributos funcionais relacionados à captação de luz teriam se diversificado através de diferentes grupos filogenéticos, conferindo a estes capacidades distintas para a conquista de novos ambientes de luz. Nosso trabalho teve como objetivo detectar a presença de padrões filogenéticos na distribuição e nas respostas ecofisiológicas de oito espécies lenhosas co-ocorrentes e de seus respectivos clados em um sub-bosque florestal, a partir da comparação do nicho de luz e do desempenho de plantas juvenis em resposta ao gradiente luminoso existente. Assim nossas hipóteses são de que 1) as espécies filogeneticamente próximas tem maior semelhança em estratégias adaptativas do que espécies filogeneticamente distantes; 2) a amplitude de nicho e 3) a plasticidade de atributos em resposta à luz aumentam em clados mais derivados. Os resultados apresentados aqui mostraram uma maior similaridade entre as espécies mais relacionadas do que entre aquelas que são filogeneticamente distantes, sugerindo conservação filogenética do nicho. Quanto à amplitude de nicho, também há uma influência filogenética, porém, contrário ao esperado, os clados mais antigos apresentaram um nicho mais amplo. Para a plasticidade dos atributos os resultados aqui apresentados mostram que não há padrões filogenéticos na plasticidade das respostas de espécies e clados estudados, sugerindo o efeito de outros fatores sobre a plasticidade das plantas, como efeitos ontogenéticos ou estresse ambiental.In forest environments, light is the resource that most often limits the growth, survival and reproduction in plants. Thus, the variation in light availability, regarded as one of the most important resources for woody plants in the understory, results in differences in species composition, which segregate in different light niches according to their preferences and tolerances, conferred by their adaptations and phenotypic plasticity. Extant plant traits are not only adapted to the present environment, they are also a legacy from their ancestors and, for that reason, phylogenetically related species often share similar attributes and consequently occupy similar niches, pattern known as phylogenetic conservatism. Recent studies show that functional traits related to the capture of this resource have diversified across different phylogenetic groups, giving them distinct abilities to occupy new light environments. The present study aimed to detect the presence of phylogenetic patterns in species distribution along a light gradient and in ecophysiological responses of eight co-occurring woody species and their respective clades in a forest understory. This was accomplished by comparing the light niche of juvenile plants in response to the existing light gradient, as well as their physiological plasticity in response to understory light variations. We hypothesized that (1) phylogenetic related species have greater similarity of adaptive strategies, and consequently of their niche, than more distantly related ones; and that (2) the niche breadth is wider and (3) traits plasticity is greater in more recent than in more basal clades. The results presented here showed that there is a greater niche similarity between closely related species than between those that are phylogenetically distant, suggesting niche conservatism. Regarding to niche amplitude, there is also a phylogenetic influence but, contrary to our expectations, the older clades showed a greater niche breadth. For plasticity of selected plant traits, results showed no phylogenetic pattern for the studied species and clades, suggesting that other factors act on the phenotypic plasticity of plants, such as ontogenetic effects and/or environmental stress.
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Carpenter, Kevin Joseph. "Structure and evolution of the leaf epidermis in basal angiosperms /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Wardell, Brian. "Evolution of barren STALK2/LAX PANICLE2 (BA2/LAX2) in angiosperms." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527423.
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Much of plant growth is directly or indirectly regulated by the plant hormone auxin. Although some genes involved in the auxin pathway have been characterized, there are still gaps in our knowledge of this genetic pathway. Recently, the orthologous maize genes BARREN STALK2 ( BA2) and rice gene LAX PANICLE2 (LAX2) have been cloned and characterized. Maize ba2 and rice lax2 mutant plants both show significant flaws in axillary meristem (AM) initiation, suggesting a role in auxin regulation. In support of this hypothesis, LAX2 interacts with the auxin regulating LAX PANICLE1 (LAX1) protein. My research reconstructs the evolutionary history of the BA2/LAX2 lineage and tests for conservation of BA2/LAX2 mRNA expression in diverse grasses. My results indicate that the BA2/LAX2 gene family—comprising BA2 /LAX2, BA2/LAX2-Like1 (BA2/LAX2L1), and BA2/ LAX2-Like2 (BA2/LAX2L2)—is restricted to monocots, and shows evidence of two independent gene duplication events. During its evolution, the BA2/LAX2 gene family appears to have gained a PDZ Protein Binding motif, which may allow it to interact with other proteins besides BA1/ LAX1. My expression analyses show that BA2/ LAX2 genes are expressed during multiple stages of inflorescence development, and this expression is conserved across multiple grass species. A unique floral expression pattern appears to have evolved at the base of the Joinvilleaceae lineage. My study further supports the hypothesis that BA2/LAX2 genes are functioning in multiple AM pathways.
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Renny-Byfield, Simon. "Evolution of repetitive DNA in angiosperms : examples from Nicotiana allopolyploids." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/3358.
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Allopolyploidy, interspecific hybridisation coupled with genome multiplication, is a prevailing force in the evolution of angiosperms. This thesis examines the consequences of allopolyploidy at the genomic level. The genus Nicotiana is an ideal model system for such studies as it includes allopolyploids formed over widely different time frames (recent to millions of years). The global genome composition of several diploid and allopolyploid species was analysed using a graph-based clustering approach, grouping next generation sequencing reads into clusters (families) of repetitive DNA. Such analysis enables examination of genome size change and diploidisation processes postallopolyploidy. I compared the abundance of >14,000 repeats in the young allopolyploid N. tabacum (less than 0.2 million years old) with relatives of the diploid progenitors, N. tomentosiformis (paternal genome donor) and N. sylvestris (maternal genome donor). Repetitive DNA from the paternal genome tends to be eliminated, whereas DNA from the maternal line remains largely unchanged. A newly described tandem repeat (NicCL3) paternally inherited in N. tabacum, is a striking example. Despite a predicted abundance of ~1% NicCL3 now accounts for only 0.1% of the genome in the allopolyploid, a loss repeated in some synthetic lines of N. tabacum after only four generations. Nicotiana section Repandae formed from a single hybridisation event between relatives of N. sylvestris and N. obtusifolia c 5 million years ago. Subsequent 6 diversification has produced four species where genome size varies by 33%; N. repanda showing genome upsizing and N. nudicaulis showing genome downsizing compared with the expected genome size. There was evidence for the erosion of low copy-number repetitive DNA in both allopolyploids. However in N. repanda genome downsizing has been counteracted by the expansion of a few repeat types. Notably these processes are concurrent with the failure to distinguish progenitor chromosome sets, which I argue is part of the diploidisation process.
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behera, Jyoti Ranjan, Shina Bhatia, and Aruna Kilaru. "Comparative in silico analysis of WRINKLED 1 paralogs in angiosperms." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/10.
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WRINKLED 1(WRI1), a member of AP2/EREBP class of transcription factors regulates carbon allocation between glycolytic and fatty acid biosynthetic pathway. Additionally, among the four WRI1 paralogs in arabidopsis, WRI3 and 4 but not WRI2, are also able to increase fatty acid content in different tissues. While the role of WRI1 is well established in seeds, the potential or WRI1 or its paralogs as master regulators in oil-rich nonseed tissues is poorly understood. Recent transcriptome studies of avocado (Persea americana) mesocarp revealed that the ortholog of WRI2, along with WRI1 and WRI3 was highly expressed during oil accumulation. Through transient expression assays, we further demonstrated that both PaWRI1 and PaWRI2 can accumulate oil in tobacco leaves. We conducted a comprehensive and comparative in silico analysis of WRI paralogs from a dicot, monocot and a basal angiosperm to identify distinct features associated with function. These data provide insights into the possible evolutionary changes in WRI1 homologs and allow for identification of new targets to enhance oil biosynthesis in diverse tissues.
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Trueba-Sanchez, Santiago. "Ecology, forms and functions of the basal angiosperms from New Caledonia." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT179/document.
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En raison de sa remarquable diversité végétale, de son taux d’endémisme, parmi les plus élevés au niveau mondial (79%) et de son extrême vulnérabilité, la Nouvelle-Calédonie est un des premiers hotspots de la biodiversité mondiale. L’une des remarquables originalités de la flore Calédonienne repose sur la présence de nombreux taxa reconnus, en raison de leurs positions phylogénétiques, comme appartenant aux lignées les plus anciennes des plantes à fleurs. Ces lignées d’Angiospermes « reliques » ont une valeur scientifique et patrimoniale importante, puisqu’elles sont de véritables fenêtres sur le passé. A travers l’étude des traits foliaires, de l’anatomie du bois (e.g. type d’éléments conducteurs, perforations, diamètre et longueur des vaisseaux), de l’architecture (e.g. sympoldialité vs monopodialité, phénomène de réitération, rythmicité de croissance) et de la biomécanique des axes, nous chercherons à caractériser les formes et fonctions de ces taxons. Ce projet de thèse vise à examiner les déterminants structurels et fonctionnels de la répartition spatiale actuelle des Angiospermes basales (grade ANITA + Magnoliidae) en Nouvelle-Calédonie. Dans cette perspective nous chercherons à comprendre quels sont les facteurs qui ont conduit au confinement de certains taxons à des habitats restreints ou au contraire à leur dispersion dans des milieux contrastés. Un premier volet du projet en cours, a pour objectif de caractériser la dynamique de croissance d’Amborella trichopoda et sa plasticité architecturale sous différents régimes lumineux. Certains traits écologiques de ces espèces d’Angiospermes de divergence précoce, s’ils n’ont pas contribué à la radiation des plantes à fleurs actuelles, ont pu permettre son enracinement écologique au sein de la flore du Mésozoïque et fournir un répertoire développemental pour l’explosion subséquente de leur diversité. L’identification et l’étude de ces caractères sont donc déterminantes pour la compréhension de l’évolution structurelle et fonctionnelle des plantes à fleursNew Caledonia (NC) is one of the main biodiversity hotspots (Myers 1988), this is because of its remarkable plant diversity, its endemism rates, among the highest in the world (79%), and because of the vulnerability of its flora. One of the main originalities of New Caledonia flora is based on the presence of a large number of taxa recognized, due to their phylogenetical positions, as the most ancient extant representatives of angiosperms. For a long time, New Caledonia has been considered as an early upset fragment of the Gondwana (Pelletier 2006) that suffered an interrupted history of isolation which conferred the evolutionary particularities that we observe today. However, recent evidences show that NC has derived from the Australian land during the late Mesozoic (~80 Mya), the island was then submerged during the first half of the Cenozoic (Pelletier 2006) and a reemergence of the island seems to have occurred ~37 Mya (Cluzel et al. 1998). After the reappearance of the island above the sea level, several events of recolonisation occurred and they wrought the biodiversity that we observe nowadays (Pillon 2012). NC presents humid forests which are unique relics; under the influence of climate changes, these forests have virtually disappeared from other regions of the globe (Morat et al. 1986). The lineages of “relictual” angiosperms, mainly subservient to these humid forests, have a great scientific and patrimony value, as they can be considered as genuine windows on the past. These taxa are susceptible to contain primitive characters which have either disappeared in most of the existing flowering plants, or that are still shared by a narrow number of them. The identification and the study of these characters are therefore determinants for the comprehension of angiosperms evolution. Some ecological features of these panchronic species, may have either contributed to the huge radiation of extant angiosperms, or they may have contributed to the ecological settling of angiosperms within the Mesozoic flora, providing them with a developmental repertoire for the subsequent explosion of their diversity. This PhD project aims to study the ecological, anatomical and functional diversity of basal angiosperms and it seeks to analyze the evolutionary patterns of these structural and functional features. We will consider here as “basal” angiosperms a great group of flowering plants that has diverged before the monocot and eudicot node. This group is conformed by the ANITA grade, formed by Amborella (a single species endemic to NC), Nymphaeales (waterlilies and other herbaceous aquatic plants) and Austrobaileyales (aromatic woody plants). The Magnoliid subclass, a clade of flowering of early divergence, which contains plants considered as paleodicots by Cronquist (1988), will be also included in the analysis of the « basal » taxa. More recently, the Magnoliids have been redefined as a clade comprising Chloranthales, Canellales, Laurales, Magnoliales, et Piperales (APG III, 2009). In a second part of the project, a fieldtrip to Mexico will be held in order to include speces belonging to the Chloranthaceae and Schisandraceae, as well as Cabombaceae et Nymphaeaceae, by this means, we will incorporate species belonging to all the orders of the “basal” angiosperms, reinforcing the comparative analysis. This research work will lean on the recent publications of the phylogenetic relations within basal angiosperms
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Bauer, Matthew J. "The interploidy hybridization barrier in Zea Mays L." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4448.
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Thesis (Ph. D.) University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 31, 2007) Includes bibliographical references.
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Huang, Bing-Quan. "Isolation and characterization of embryo sacs and their component cells in a synergidless (Plumbago) and a synergid-bearing (Nicotiana) angiosperm /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1991.
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Bres, Julia. "Modéliser l’évolution des plantes à fleurs au Crétacé et leurs rétroactions avec le climat." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASJ001.
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Au Crétacé, l'évolution foliaire des plantes à fleurs, ou Angiospermes, vers de fortes densités de nervures et de stomates, suggère une augmentation de la conductance stomatique et des flux d’évapotranspiration sans précédent. Cependant, ces paléo-traits ne sont pas pris en compte dans les modèles de végétation qui visent justement à déterminer les effets de l’évapotranspiration sur le climat. L’objectif de ma thèse est donc de modéliser l’évolution de la conductance stomatique des plantes à fleurs au cours du Crétacé et d’en évaluer ses effets sur les interactions et rétroactions climat-végétation. En combinant des données fossiles et des modèles écophysiologiques, je développe une paramétrisation innovante de la végétation proto-angiosperme dans le modèle de végétation ORCHIDEE qui considère une réduction conjointe de leurs capacités hydrauliques et photosynthétiques. Avec le modèle couplé atmosphère-végétation LMDZOR, je montre que la radiation des Angiospermes génère un renforcement du cycle hydrologique et une baisse de la température de surface, dont les intensités sont modulées par la teneur en CO2 atmosphérique. En activant le modèle de végétation dynamique, je montre que la radiation des plantes à fleurs génère des boucles de rétroactions positives dans un contexte de baisse de la teneur en CO2 atmosphérique au cours du Crétacé : l’augmentation des capacités hydrauliques et photosynthétiques des plantes à fleurs constitue un avantage sélectif par rapport aux autres types de plantes qui leur permet de (i) maintenir leur productivité, (ii) développer des forêts tropicales et remplacer les conifères dans les forêts tempérées et boréales et (iii) renforcer les précipitations, limitant ainsi les effets du stress hydrique sur leur propre essorDuring the Cretaceous period, the leaf evolution of flowering plants, or angiosperms, towards higher vein and stomata densities, suggests an unprecedented increase in stomatal conductance as well as evapotranspiration fluxes. However, these paleo-traits are not accounted for in vegetation models whose the aim is to evaluate the effects of evapotranspiration fluxes on the climate system. The purpose of this study is to simulate the stomatal conductance evolution of flowering plants through the Cretaceous period and assess their effects on interaction and feedback between climate and vegetation. By combining fossil data and empirical ecophysiological models, I develop an innovative parameterization of proto-angiosperm vegetation in the ORCHIDEE vegetation model which considers a reduction of both hydraulic and photosynthetic capacities. Thanks to the coupled atmosphere-vegetation model LMDZOR, I demonstrate that the radiation of flowering plants drives a strengthening of the hydrologic cycle and a decrease in surface temperature, the intensities of which are modulated by the atmospheric concentration of CO2. By activating the dynamic vegetation model, I show that flowering plant radiation triggers positive feedback loops in a context of decreasing atmospheric concentration of CO2 during the Cretaceous period: the increase in hydraulic and photosynthetic capacities of flowering plants constitutes a selective advantage compared to other types of plants by allowing them to (i) sustain their productivity, (ii) develop tropical forests and replace conifers in temperate and boreal forests and (iii) enhance precipitations, thus preventing water stress effects on their own development
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Child, Robert Joseph. "The evolution of BARREN INFLORESCENCE1 and related AUX/IAA genes in angiosperms." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527538.
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The plant hormone auxin plays a major role in shaping plant morphology and development, but the gene networks regulating its synthesis and transport are incompletely known. The maize BARREN INFLORESCENCE 1 (BIF1) gene has recently been cloned and shown to play an important role in the early stages of polar auxin transport. Auxin is synthesized in shoot tips and transported basipetally through the plant shoot and acts as a morphogen by facilitating the degradation of transcriptional repressors in a concentration dependent manner. The AUX/IAA gene family encodes transcriptional repressors that regulate a subset of plant developmental responses governed by the transcription of early auxin inducible genes in plants. Although the maize BIF1 gene is a member of the AUX/IAA gene family, the co-ortholog(s) of BIF1 in Arabidopsis thaliana was not known prior to this research.
Bayesian phylogenetic reconstruction placed maize BIF1 in a clade sister to Arabidopsis thaliana AtIAA15. The BIF1 lineage has undergone two gene duplications since the divergence of the early grasses. Molecular evolutionary analyses by maximum likelihood suggest that the BIF1 alignment is under strong purifying selection with positive selection acting on a glutamine residue located in a functional region associated with AUX/IAA protein dimerization in one clade of BIF1 paralogs, the BIF1-Like2 (BIF1L2) clade. A character reconstruction analysis using maximum parsimony estimated an adenine to cytosine transversion at the base of the BIF1L2 clade changed a glutamine into an alanine residue in this functional region. Expression of BIF1 orthologs is conserved in floral meristems in the eudicot AtIAA15 clade containing the taxa Erianthe Guttata, Arabidopsis thaliana, Medicago truncatula, however grass BIF1L2 expression has diverged within the PACMAD – BEP clade, specifically in rice, where BIF1L2 expression is reported to have moved into root tissue. These results suggest that BIF1 paralogs has changed following a second round of gene duplication in the grasses. Taken together, a change in localized expression in these sequences, and positive selection acting on a glutamine-rich region of the protein-protein binding motif could imply that BARREN INFLORESCENCE1-like2 proteins are probably interacting with a new set or subset of AUXIN RESPONSE FACTOR (ARF) binding partners, and that neofunctionalization has occurred in the BARREN INFLORESCENCE1-like2 clade.
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Quested, Helen M. "Root hemiparasitic angiosperms in subarctic ecosystems : their potential role in ecosystem function." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246953.
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Barba-Montoya, J. A. "Bayesian molecular clock dating and the divergence times of angiosperms and primates." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1565539/.
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The explosive increase of molecular sequence data has produced unprecedented opportunities for addressing a number of evolutionary problems. Specially, the species divergence time estimation is fundamental because our understanding of history of life depends critically on knowledge of the ages of major clades. This thesis explores the use of molecular data (genome-scale datasets), combined with statistical summaries of the fossil record, to date the origin of angiosperms (flowering plants) and the divergence times of its major groups in an attempt to resolve the apparent conflict between the molecular dates and fossil evidence. Moreover, because fossil calibrations are the major source of information for resolving the distances between molecular sequences into estimates of absolute times and absolute rates in molecular clock dating analysis, several strategies for converting fossil calibrations into the prior on times are evaluated. Chapter one introduces the diversity and evolution of angiosperms, reviews the current literature that is based predominantly on systematics, phylogenetics, palaeobotany and plant molecular evolution. In introducing the early evolution of angiosperms this chapter highlights the questions associated with the origin of angiosperms and presents aims of the thesis. Chapter two focuses on molecular clock dating methods. It discusses different approaches for estimating divergence times, with emphasis on Bayesian molecular clock dating methods. Chapter three uses a powerful Bayesian method to analyze a molecular dataset of 83 genes from 644 taxa of vascular plants, combined with a suite of 52 fully-justified fossil calibrations to disentangle the pattern of angiosperm diversification. The results indicate that crown angiosperms originated during the Triassic to the Jurassic interval, long prior to the Cretaceous Terrestrial Revolution. This analysis demonstrates that even though many sources of uncertainty are explored, attempts to control for these factors still do not bring clock estimates and earliest confident fossil occurrences into agreement. A post-Jurassic origin of angiosperms was rejected, supporting the notion of a cryptic early history of angiosperms. The main factors affecting the estimates in this study are also discussed. Subsequently, in chapter four different strategies for summarizing fossil information to construct calibration priors were assessed employing an a priori procedure for deriving accurate calibration densities in Bayesian divergence dating. In general, truncation has a great impact on calibrations so that the effective priors on the calibration node ages after the truncation can be very different from the user-specified calibration densities. The different strategies for generating the effective prior also had considerable impact, leading to very different marginal effective priors. Arbitrary parameters used to implement minimum-bound calibrations were found to have a strong impact upon the prior and posterior of the divergence times. The results highlight the importance of inspecting the joint time prior used by the dating program before any Bayesian dating analysis. Finally, chapter five draws together key finding from chapters three and four, and reviews how this work advances our understanding of the origin and evolution of angiosperms and on molecular clock dating using fossil calibrations. This chapter also highlights new gaps in our understanding of early evolution of angiosperms and in the implementation of fossil calibrations in Bayesian molecular clock dating, and discusses several areas for future research. Overall, this thesis highlights that more room for improvement might lie in refining our knowledge and use of fossil calibrations, the resulting improvements to molecular estimates of timescales will lead to a better understanding of angiosperm evolution. I speculate that these results will also shed light on dating discrepancies in other major clades.
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La-aw, Ampornpan Armstrong Joseph E. "Ontogeny of zygomorphic flowers in the Solanaceae." Normal, Ill. Illinois State University, 1992. http://wwwlib.umi.com/cr/ilstu/fullcit?p9311282.
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Thesis (Ph. D.)--Illinois State University, 1992.Title from title page screen, viewed January 31, 2006. Dissertation Committee: Joseph E. Armstrong (chair), Mathew M. Nadakavukaren, Tsan Iuan Chuang, Roger C. Anderson, Jerome R. Cain. Includes bibliographical references (leaves 94-101) and abstract. Also available in print.
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Ingram, Gwyneth. "The role of the fimbriata gene cluster in plant development." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317998.
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Loehne, Cornelia. "Molecular phylogenetics and historical biogeography of basal angiosperms a case study in Nymphaeales /." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=983926468.
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Thomas, Paul William. "Long-distance systemic irradiance signalling : the extent, nature and mechanism in vascular angiosperms." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421164.
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Crawley, Sunny Sheliese. "Rethinking phylogenetics using Caryophyllales (angiosperms), matK gene and trnK intron as experimental platform." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77276.
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The recent call to reconstruct a detailed picture of the tree of life for all organisms has forever changed the field of molecular phylogenetics. Sequencing technology has improved to the point that scientics can now routinely sequence complete plastid/mitochondrial genomes and thus, vast amounts of data can be used to reconstruct phylogenies. These data are accumulating in DNA sequence repositories, such as GenBank, where everyone can benefit from the vast growth of information. The trend of generating genomic-region rich datasets has far outpaced the expasion of datasets by sampling a broader array of taxa. We show here that expanding a dataset both by increasing genomic regions and species sampled using GenBank data, despite the inherent missing DNA that comes with GenBank data, can provide a robust phylogeny for the plant order Caryophyllales (angiosperms). We also investigate the utility of trnK intron in phylogeny reconstruction at relativley deep evolutionary history (the caryophyllid order) by comparing it with rapidly evolving matK. We show that trnK intron is comparable to matK in terms of the proportion of variable sites, parsimony informative sites, the distribution of those sites among rate classes, and phylogenetic informativness across the history of the order. This is especailly useful since trnK intron is often sequenced concurrently with matK which saves on time and resources by increasing the phylogenetic utility of a single genomic region (rapidly evolving matK/trnK). Finally, we show that the inclusion of RNA edited sites in datasets for phylogeny reconstruction did not appear to impact resolution or support in the Gnetales indicating that edited sites in such low proportions do not need to be a consideration when building datasets. We also propose an alternate start codon for matK in Ephedra
based on the presense of a 38 base pair indel in several species that otherwise result in pre-mature stop codons, and present 20 RNA edited sites in two Zamiaceae and three Pinaceae species.Ph. D.
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Osborn, Jeffrey Mark. "Comparative ultrastructure of fossil gymnosperm pollen and implications regarding the origin of angiosperms /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487757723994964.
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Ruszala, Elizabeth Mary. "Conservation aspects of stomatal function and development between the lycophyte selaginella and model angiosperms." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546219.
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Burger, Matthias [Verfasser]. "Functional in vivo analysis of RNA editing factors in bryophytes and angiosperms / Matthias Burger." Ulm : Universität Ulm, 2021. http://d-nb.info/1227450745/34.
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Oh, Il-Chan. "Comparative Seed Morphology and Phylogenetics : Case Studies in Basal Angiosperms (ANITA) and Asterids (Lysimachia, Ericales)." Doctoral thesis, Uppsala universitet, Systematisk biologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-100372.
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The first half of the thesis deals with the seed morphology of members of the ANITA grade at the base of the angiosperm phylogeny (Amborella, Nymphaeales, Illiciales, Trimeniaceae, and Austrobaileyaceae), especially Illiciaceae and Schisandraceae. Seed characters support a major division between the New World and Old World species of Illicium. Fossil seeds previously assigned to Illiciaceae were re-evaluated. In Schisandraceae, seed and leaf epidermal characters were added to a previously published morphological data matrix. Phylogenetic analysis using the extended data matrix shows that Kadsura and Schisandra appear to be supported as monophyletic sister taxa by a number of synapomorphies in reproductive and vegetative characters. Fossil seeds from the Eocene of North America show some similarities to the modern Schisandra glabra from North America, whereas fossils from Europe are more similar to modern Asian species. In the second half of the thesis, seed morphology of Lysimachia and closely related taxa (Anagallis, Ardisiandra, Asterolinon, Glaux, Pelletiera, Trientalis) was investigated. The phylogenetic relationships among the endemic Hawaiian species of Lysimachia was also studied, using nuclear ribosomal DNA (ETS, ITS) and chloroplast DNA (rpl16, rpl20-rps12, rps16, trnH-psbA, trnS-G) sequence data. The seeds in Lysimachia and related taxa vary in, e.g., shape, seed coat structure and surface patterns. Seed surface patterns are mostly congruent with molecular phylogenetic relationships. A reticulate surface pattern is diagnostic for, e.g., the subgenus Palladia and the Hawaiian endemic subgenus Lysimachiopsis. Mapping seed characters onto a recent molecular-based phylogenetic tree, reveals that they provide potentially synapomorphic character states for various subclades of Lysimachia. The phylogenetic analysis based on the combined data set using nuclear ribosomal DNA and chloroplast DNA data provides new insights into the relationships within the Hawaiian subgenus Lysimachiopsis. Here our results indicate that earlier taxonomic treatments of the group need to be partially revised.
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Yagi, Eiki. "The distribution of the Au SINE family in angiosperms and gymnosperms and its evolutionary history." Kyoto University, 2012. http://hdl.handle.net/2433/157684.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第16893号
農博第1909号
新制||農||996(附属図書館)
学位論文||H24||N4654(農学部図書室)
29568
京都大学大学院農学研究科応用生物科学専攻
(主査)准教授 河原 太八, 教授 遠藤 隆, 教授 奥野 哲郎
学位規則第4条第1項該当
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Guignard, Maite Stephanie. "Ecological consequences of angiosperm genome size and macronutrient availability." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24632.
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Genome size (GS) is a fundamental trait influencing cellular, developmental and ecological parameters, and varies c. 2400- fold in angiosperms. This astonishing range has the potential to influence a plant's nutrient demands, since nucleic acids are amongst the most phosphate and nitrogen demanding cellular biomolecules, and hence its ability to grow and compete in environments where macronutrients are limited. Angiosperm GS are strongly skewed towards small genomes, despite the prevalence of polyploidy in the ancestry of most if not all angiosperm lineages. This thesis examines the hypothesis that large genome sizes are costly to build and maintain and that angiosperm species with large GS are constrained by nitrogen and phosphate limitation. It untangles the interactions between GS, polyploidy and competition in plant communities, and examines how herbivory and GS play a role in plant productivity, measured as above-ground biomass. The hypothesis that large GS are costly was approached by analysing: 1) plant communities growing under different macronutrient conditions at the Park Grass Experiment (Rothamsted, UK); 2) plant communities under different conditions of macronutrient limitation and insect, mollusc, and rabbit herbivory at Nash's Field in Silwood Park (UK); and, 3) Ellenberg's indicator values which represent the realised niche of a species in terms light, water, and soil fertility. Support for the hypothesis was found in all experiments. The range of analyses show that angiosperm plants with large genomes (e.g. 1C-value > 5 pg) are indeed under greater macronutrient limitation in comparison to plants with small genomes, and that it is polyploid plants with large GS which are the most competitive when macronutrient resources are plentiful. In terms of herbivory, the key finding is a highly significant negative association between GS and rabbit herbivory. A species' realised niche for soil fertility was found to show a positive association with its GS. Overall the thesis shows that angiosperm GS plays a central role in plant community composition and responses to macronutrient conditions, and potentially on higher ecosystem processes through associations at different trophic levels.
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Mahfoud, Hafez M. "Evolution of the genus Aristolochia (Aristolochiaceae) in the Eastern Mediterranean including the Near East and Caucasia." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-27142.
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The Aristolochiaceae are one of the largest angiosperm families, the family has been divided into two subfamilies: Asaroideae, which include Asarum and Saruma, and Aristolochioideae, which includes Thottea sensu lato and Aristolochia sensu lato (Kelly and Gonzales, 2003). Aristolochia sensu lato comprise between 450 and 600 species, distributed throughout the world with centers of diversities in the tropical and subtropical regions (Neinhuis et al., 2005, Wanke et al., 2006a, 2007).
However, the extended Mediterranean region including Turkey, the Caucasus and the Near East is likely to be the only diversity hotspot of the genus Aristolochia in the northern hemisphere were up to 60 species and subspecies could be observed (Wanke 2007). Most important contributions to the knowledge of these species were published by Nardi (1984, 1988, 1991, 1993) and Davis & Khan (1961, 1964, 1982), all of these studies were based on morphological characters only. In recent years, with the progress of molecular techniques and in light of the systematic chaos, a detailed study was needed to unravel the evolutionary history prior to a taxonomic revision of this group. The first chapter of my thesis should be regarded as the starting point for more detailed investigation on population level.
Preliminary molecular phylogenitic analysis recovered the Mediterranean Aristolochia species as monophyletic (de Groot et al 2006). However, only very few members were included in that study. The latest phylogenetic study by Wanke (2007) dealed with west Mediterranean Aristolochia species and sampled also few members belonging to the east Mediterranean and Caucasian species (3 from Greece, 2 from Georgia and 1 from Turkey). This study reported the Mediterranean Aristolochia species as two molecular and morphologically well supported clades, which were sister to each other. Furthermore, the two closely related species A. sempervirens and A. baetica which have an east west vicariance and are known as Aristolochia sempervirens complex has been recovered as sister group to the remaining west Mediterranean species. A detailed investigation of the evolutionary history of this group is the topic of the second chapter of my thesis (Chapter 2). The Aristolochia sempervirens complex is characterized by an unusual growth form and has a circum Mediterranean distribution. The investigation of these species complex seem to be of great importance to understand speciation and colonization of the Mediterranean by the genus Aristolochia and might shade light in historical evolutionary processes of other plant lineages in the Mediterranean. Furthermore, I test applicability and phylogenetic power of a nuclear single copy gene (nSCG) region to reconstruct well resolved and highly supported gene genealogies as a prerequisite to study evolutionary biology questions in general.
Furthermore, a comprehensive overview of leaf epicuticular waxes, hairs and trichomes of 54 species from the old and new world taxa of the genus Aristolochia were investigated using scanning electron microscopy (SEM) to clarify taxonomic status of theses species in contrast to their molecular position. Also this study which is the third chapter of this thesis (Chapter 3), has a strong focus on Mediterranean Aristolochia and tries to provide additional support for molecular findings based on epicuticular waxes and to test them as synapomorphies.
Each chapter has its own introduction and abstract resulting in a short general introduction here.
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Ontoria, Gómez Yaiza. "Seagrass responses to climate change: effects of warming and the interaction with local stressors = Respuestas de las angiospermas marinas al cambio climático: efectos del calentamiento y la interacción con estresores locales." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/669000.
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Coastal ecosystems are highly threatened worldwide by multiple anthropogenic stressors that act at a range of spatial scales, from local to the global, and adversely affect their ecological functions and associated biodiversity. Global warming is one of the most pervasive stressors, and the assessment of how the species (or other levels of biological organization) react to it is an urgent need in a rapidly warming world. Moreover, thermal stress rarely acts in isolation from other stressors. The potential synergies among global warming and local stressors is of particular concern in what it regards foundation species, such as the case of seagrasses, due to their crucial role in maintaining the structure and function of coastal ecosystems. The main objective of this PhD thesis is to improve the knowledge of how warming alone and in combination with different local factors can affect seagrasses. This research has been conducted based upon mesocosm experiments submitted to different temperatures (and, in some cases, to other agents), and plants responses measured from biochemical to population levels. The results obtained are considered an approach to what may occur in the real world, always acknowledging the limitations of our methodology.
Chapter 1 revealed different tolerance to warming among the two main Mediterranean seagrass species, Cymodocea nodosa and Posidonia oceanica. C. nodosa tolerates temperature increases much better than P. oceanica probably due to its life story (opportunistic), habitat (from confined waters to the open sea) and biogeographical affinity (tropical and subtropical). This will potentially cause changes in the distribution area of these two species in the Mediterranean under a future scenario of warming.
As shown in Chapter 2, an increase in nutrient concentration in water does not modify the response of C. nodosa to warming. However, the increase of organic matter in sediment clearly worsens, synergistically in some plant traits, the effects of warming, entailing a hazardous combination for plant survival. P. oceanica, in turn, is severely affected by conditions of high nutrient content and high temperatures (Chapter 3), again displaying synergistic effects, and confirming not only a thermal sensitivity in this species greater than in C. nodosa, but also a greater vulnerability to the exacerbation of thermal effects by other local stressors.
Finally, the interactive effects of warming and salinity (Chapter 4) in an estuarine seagrass species, Halophila ovalis, in southwestern Australia resulted beneficial for plant survival, as the negative effect of warming was buffered by concomitant salinity increases.
Overall, this research highlights the complexity of global warming effects in at least two aspects. Firstly, the multiplicity of biological levels at which those effects act and, secondly, the importance of studying not only isolated effects of temperature increases but also their joint effect with other stressors. Advances in these two directions will yield more realistic predictions concerning global warming and seagrass ecosystems and help to develop management policies to protect seagrass ecosystems in a changing world.
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Day, Robert Charles, and n/a. "Transcript analysis of proliferative endosperm from Arabidopsis thaliana." University of Otago. Department of Biochemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080703.113233.
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Arabidopsis has emerged as an important model system for molecular plant biology. The extensive resources available for Arabidopsis make it an attractive system to study the molecular mechanisms involved in early seed development. During the early stages of seed development Arabidopsis endosperm is syncytial and proliferates rapidly through repeated rounds of mitosis without cytokinesis. This stage of endosperm development is both important in determining final seed size and is a model for studying various aspects of cellular and molecular biology, such as the cell cycle and genomic imprinting. However, the small size of Arabidopsis seed, the syncytial nature of the proliferative endosperm, and the surrounding maternal tissues make high throughput molecular analysis of the early endosperm technically difficult.
To get around this we used laser capture microdissection to enable transcript analysis of the early proliferative endosperm of Arabidopsis at 4 days after pollination (DAP). Microarray results identified several thousand genes with endosperm expression, including many that were endosperm preferred. A number of genes were validated by relative quantification PCR and were consistent with the findings of the microarray. Meta analysis of the endosperm transcriptome revealed a developmental program dominated by mitosis and under the influence of several phytohormones, predominated by cytokinin signaling.
The list of endosperm-preferred genes included all characterised imprinted genes in Arabidopsis. Imprinting is an epigenetic phenomenon by which genes are expressed predominantly from either their paternal or their maternal allele and very few imprinted genes have been identified in plants. The mono-allelic expression of the characterised imprinted genes appears to be limited to the endosperm where they provide important regulatory controls for seed development via direct effects on endosperm development. Genes from the endosperm-preferred list were screened for mono-allelic expression using sequence polymorphisms between the Colombia and Landsberg erecta ecotypes. We generated PCR products that spanned the polymorphisms of 67 genes from template obtained by laser capture of endosperm tissue from hybrid seed. Sequence analysis revealed three genes which gave strong allelic bias toward the maternal allele (At2g32460, At1g55550 and At2g21420) and one biased for the paternal allele (At1g47840).
In summary, laser capture microdissection has enabled high-resolution transcript analysis of the proliferative stage of Arabidopsis endosperm development. The data generated provides a useful resource providing novel insight into early seed development, facilitating both identification of endosperm expressed and novel imprinted genes.
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Cameron, Duncan Drummond. "A role for differential host resistance to the hemiparasitic angiosperm, Rhinanthus minor L. in determining the structure of host plant communities?" Thesis, University of Aberdeen, 2004. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238495.
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This study describes the effect of the root hemi-parasitic angiosperm Rhinanthus minor on the structure of the communities in which it lives and seeks to elucidate a mechanism through which the parasite acts to effect these changes in the community. Field manipulations reveal that R. minor suppressed the growth of grasses and legumes in a newly sown meadow whilst promoting the forbs within one growing season. In contrast the removal of R. minor from mature meadow plots did not influence their composition. After an additional growing season the parasite did not further influence the composition of the new meadows but removal did begin to benefit the biomass of mature plots. In isolation the parasite caused most damage to grasses whilst leaving legumes and forbs undamaged. Moreover, the parasite performed worst in terms of growth and photosynthesis when attached to the forbs. Consequently the parasite was able to moderate intra-specific competition between grasses and forbs. I thus hypothesised that forbs were able to prevent the parasite form abstracting resources where as grasses could not. Tracer experiments using isotopically e5N) labelled potassium nitrate confirmed this hypothesis showing that more of the resources taken up by the host were stolen by the parasite from grasses than from forbs. There was much variability in the translocation of resources from the legume studied. The reasons underlying the differential uptake of resources were highlighted using histological studies which showed that all of the forbs possessed successful resistance mechanisms to the parasite whilst no successful resistance was observed in the grasses or legumes. Two different resistance mechanisms were observed in the forbs; hypersensitive cell-death at the host-parasite interface and host lignification. I therefore propose that differential host resistance may underlie this parasite's community level effects as forbs possess a resistance capacity that other potential hosts do not.
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Savard, Joël. "On the evolutionary origin of angiosperms : characterization of MADS-box floral homeotic gene homologues in Ephedra andina (Gnetales)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0034/MQ64446.pdf.
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Faiyue, Bualuang. "Bypass flow and sodium transport in rice (Oryza sativa L.)." Thesis, University of Sussex, 2011. http://sro.sussex.ac.uk/id/eprint/6309/.
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An apoplastic pathway, the so-called bypass flow, is important for Na+ uptake in rice under saline conditions. The primary aim of this thesis was to identify the point of entry for bypass flow into rice roots subjected to salinity. Investigations using lateral rootless mutants (lrt1, lrt2), a crown rootless mutant (crl1), their wild types (Oochikara, Nipponbare and Taichung 65, respectively) and seedlings of rice cv. IR36 showed that the entry point, quantified using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), was not at the sites of lateral root emergence. However, PTS was identified in the vascular tissue of lateral roots using both epifluorescence microscopy and confocal laser scanning microscopy. Cryo-scanning electron microscopy and epifluorescence microscopy of sections stained with berberine-aniline blue and Fluorol Yellow 088 revealed that an exodermis was absent in the lateral roots, suggesting that the lack of the exodermis allowed PTS to pass through the cortical layers, enter the stele and be transported to the shoot via the transpiration stream. These findings suggest a role for the lateral roots of rice in bypass flow. The addition of polyethylene glycol (PEG) and silicon (Si) to the culture solution significantly reduced Na+ uptake to the shoot by reducing bypass flow through the lateral roots. PEG was found to be more effective than Si. It was also shown that changing the relative humidity in the air around the shoots had a significant effect on the magnitude of bypass flow and the flux of water across the roots: the greater the flux of water through the roots, the greater the Na+ uptake and bypass flow. Furthermore, results showed that recombinant inbred lines of rice with low Na+ transport possessed low magnitudes of bypass flow, whereas lines with high Na+ transport had a high degree of bypass flow, indicating that bypass flow could be used as a criterion for screening salt resistance in rice varieties.
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Li, Huan [Verfasser], and Dario [Akademischer Betreuer] Leister. "Large scale plastomics approaches for the study of evolution and adaptive signatures in angiosperms / Huan Li ; Betreuer: Dario Leister." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1172634343/34.
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Smith, Michaela Madeleine 1972. "Maintenance of ultrastructural integrity during dehydration in a desiccation tolerant angiosperm as revealed by improved preservation techniques." Monash University, Dept. of Biological Sciences, 2002. http://arrow.monash.edu.au/hdl/1959.1/8323.
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Martínez, Harms Jaime [Verfasser]. "Color vision of insect pollinators : photoreceptor properties, behavioral bases and its implications for the evolution of angiosperms / Jaime Martínez Harms." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1030382972/34.
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Crifo, Camilla. "VARIATIONS IN ANGIOSPERM LEAF VEIN DENSITY HAVE IMPLICATIONS FOR INTERPRETING LIFE FORM IN THE FOSSIL RECORD." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1375987428.
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Sheth, Mili. "Discovery and characterization of KNOX proteins lacking a homeodomain, produced by alternative splicing of KNAT1-like genes in gymnosperms and angiosperms." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31639.
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Kidd, A. D. "Studies on DNA replication and the cell cycle in the root meristem of fifteen monocotyledonous angiosperms of heterogeneous DNA C values." Thesis, Bucks New University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376419.
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Dahlgren, Linnea. "Bumblebees in a region of northwestern Scania: Is species number correlated to the number of flowering angiosperms and does gene flow occur between four locations?" Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-24564.
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Pollination, one of our ecosystem services, is considered to be in critical condition due to a worldwide reduction in pollinators and their biodiversity. As the agricultural landscape becomes more and more intense, the pollinators lose important food and living resources. In temperate ecosystems, bumblebees (Bombus spp) are an important group of wild pollinators, and as with pollinators in general, they are declining in both abundance and richness, in Sweden as well as other countries. The purpose of this study was to see if bumblebee species number of a location is linked to the location’s number of flowering angiosperm species in northwestern Scania when examining eight locations, and to see if gene flow existed between four chosen locations. The result of this study suggests that it is not possible to tell from the flowering angiosperm species how many bumblebee species that will be abundant, but that it might be possible to tell the number of bumblebee individuals. With the number of bumblebee species, the abundant Fabaceae species was more important than the total number of flowering angiosperms of the location. The number of abundant Fabaceae species was strongly correlated to the bumblebee diversity index of the locations, indicating that it is a group of flowers closely linked to bumblebees. To see if gene flow occurred between the chosen locations, mtDNA sequences were compared in neighbor joining trees. The result showed that though some tendencies of isolation existed, gene flow seemed to occur in general between the locations in that fragmented and human dominated landscape of northwestern Scania.
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Sperlich, Dominik. "Mediterranean forests in a changing environment - Impacts of drought and temperature stress on tree physiology." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/327595.
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The Mediterranean Basin is a climate-change hotspot of the world. Predicted reductions in annual precipitation, increases in mean temperature, and increases in the variability and occurrence of extreme droughts and heat waves are likely to affect species abundance and distribution. The existence of sympatric plants with different morphological and phenological strategies raises the question how they will respond to novel climate conditions. There is a strong need to improve the mechanistic understanding of key foliar ecophysiological parameters in response to abiotic stressors on a small scale if we are to predict the carbon budget of plant ecosystems in larger scales.
We first reviewed contrasting growth responses to temperature of angio- and gymnosperms in the Iberian Peninsula. Secondly, we studied the seasonal acclimation of different foliar ecophysiological traits in two leaf positions of four Mediterranean tree species in extensive field experiments. We aimed to shed light on the mechanistic understanding of the foliar respiratory and photosynthetic responses to abiotic stress such as drought and temperature.
We found contrasting demographic responses in Mediterranean conifer and angiosperm trees. Widespread forest successional advance of angiosperms and negative growth responses of gymnosperms to temperature are currently occurring in the Iberian Peninsula. Trait-based differences in these two groups contribute to explain their different responses to temperature and their different role during successional processes.
The acclimation behaviour of photosynthetic and morphological traits to seasonal variable growth conditions was strongly pronounced in all tree species. Photosynthetic machineries were resilient to moderate drought, whereas severe drought induced acclimation of morphological traits, photosynthetic downregulation and leaf abscission. The lack of replenishment of soil-water reserves during the early growing season critically enforced the summer drought.
We also observed a notable seasonal acclimation of the thermal optima and of the curvature of temperature responses of photosynthetic assimilation. The photosynthetic system was better acclimated to lower temperatures in winter and to heat stress in the drier and hotter year.
Mild winter temperatures provided a period of growth and recovery that resulted in biochemical recovery, new shoot growth, and moderate transpiration across all evergreen species. High radiation and sudden low temperatures had a combinatory negative effect on the photosynthetic apparatus leading to photoinhibitory stress -especially in sunlit leaves.
Species-specific acclimation partly offset these overall trends in responses to drought and temperature stress. Quercus ilex L. and to a lesser extent Q. pubescens Wild. showed the highest plasticity in photosynthetic traits whereas Pinus halepensis Mill. was most tolerant across the seasons with the most stable temperature response pattern. Arbutus. unedo L. was the most vulnerable to drought and photoinhibitory stress in winter. A. unedo and Q. pubescens had a less sclerophyllic leaf habit and invested the least in acclimation of the morphological structure being most vulnerable to drought-induced leaf abscission. Shaded leaves showed generally a lower photosynthetic potential, but cushioned negative impacts under stress periods. A long-term rainfall-exclusion experiment in a Q. ilex forest increased the foliar carbon-use efficiency and the plasticity of foliar respiratory and photosynthetic traits, but did not affect the biochemical photosynthetic potential. A favourable growth period was thus exploited more efficiently. Overall, our results indicate that Mediterranean climax-species exhibit a strong acclimatory capacity to warmer and drier conditions, but can be sensitive to extreme drought and extreme temperature stress. The performance of the plants during winter might give important insights in the dynamics of Mediterranean forest communities under novel environmental conditions. Leaf position is an indispensable factor when estimating the canopy carbon balance. Angiosperms and gymnosperms had fundamental different photosynthetic strategies of stress-avoidance versus stress-tolerance, respectively.El cambio climático aumentará la sequía en la Cuenca Mediterránea y posiblemente afectará a la abundancia y la distribución de especies. Revisamos las respuestas contrastadas del crecimiento a la temperatura de angio- y gimnospermas en la Península Ibérica. Estudiamos la variación de los efectos del estrés térmico y por sequía en rasgos morfológicos, fotosintéticos y de la respiración foliar según la especie y la posición en el dosel. Además, evaluamos el efecto de una sequía crónica sobre la respiración foliar y la fotosíntesis de Quercus ilex L. La maquinaria fotosintética se mostró resiliente frente a la sequía moderada, mientras que la sequía extrema, agravada por las bajas reservas de agua en el suelo, indujo la aclimatación de la morfología foliar, la inhibición de la bioquímica fotosintética y la abscisión foliar. El sistema fotosintético se aclimató mejor a las temperaturas bajas que al estrés por calor. Las temperaturas suaves en invierno derivaron en la recuperación bioquímica, un nuevo crecimiento de los brotes y una transpiración moderada. La elevada radiación y el frío repentino mostraron un efecto combinado negativo, causando estrés fotoinhibitorio. El estrés térmico y por sequía fue más pronunciado en hojas de sol y aminorado en hojas de sombra. Q.ilex y, en menor grado, Q. pubescens Wild. mostraron la plasticidad más elevada de los rasgos fotosintéticos, mientras que Pinus halepensis Mill. fue más tolerante, mostrando la respuesta más estable a la temperatura. Arbutus unedo L. fue la especie más vulnerable a la sequía y al estrés fotoinhibitorio. En respuesta a la sequía crónica, Q. ilex incrementó la eficiencia en el uso del carbono y la plasticidad de los atributos fotosintéticos y de respiración foliar, pero no afectó al potencial fotosintético. En resumen, las especies climácicas mediterráneas se aclimatan frente a condiciones más cálidas y secas, pero pueden ser sensibles ante sequías extremas. El funcionamiento durante el invierno es vital para entender la dinámica de los bosques mediterráneos. La posición de las hojas en la copa es indispensable para estimar el balance de carbono del dosel. Angiospermas y gimnospermas presentan estrategias fotosintéticas contrastadas, de evitación y tolerancia del estrés, respectivamente.
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Silveira, Carina Lima da. "Características vegetativas e reprodutivas das plantas e fatores abióticos do meio e suas relações com a alocação de biomassa floral e a seleção sexual em angiospermas." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316105.
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Orientador: Marlies SazimaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: As plantas são organismos sésseis que estão à mercê do estresse ambiental. As flores são estruturas fundamentais na evolução das angiospermas, pois através delas ocorre a reprodução sexuada. Para isto, as flores exibem estratégias que auxiliam a planta a obter melhor sucesso reprodutivo. Animais visitam flores em busca de recursos, no entanto, ao transportar grãos de pólen entre os indivíduos da mesma espécie vegetal, atuam como mediadores no processo de seleção sexual, importante força na evolução florai. Fatores ecológicos que afetam a relação entre plantas e polínizadores podem influenciar a evolução das estratégias reprodutivas das espécies. Fatores abióticos, a distribuição espacial, o tamanho populacional e a história de vida das plantas podem modificar a abundância e a distribuição dos recursos para os polínizadores, alterando padrões de transporte de pólen, fluxo gênico e pressões seletivas responsáveis pela evolução floral. Este trabalho busca compreender a diversidade das estratégias reprodutivas em diferentes formações vegetais tropicais, a modulação por características vegetativas e reprodutivas das plantas e abióticas do meio na alocação de recursos como, também, verificar a existência de consistência biogeográfica dos padrões alométricos em relação as estratégias reprodutivas das plantas. O estudo foi realizado em áreas de vegetação tropical, sendo uma área de Floresta Atlântica, uma área de Cerrado, ambas no estado de São Paulo e uma área de Campo Rupestre, no estado de Minas Gerais, permitindo a comparação da variação da biomassa floral entre as três formações vegetais e entre angiospermas tropicais com particularidades morfológicas relacionadas às áreas de coleta e dados bibliográficos de espécies extra-tropicais. A riqueza de formas vegetais e de ambientes nas regiões tropicais atua na modulação da interação entre plantas e polínizadores, influenciando na variação da biomassa floral e nas características vegetativas e reprodutivas das espécies. As alometrias positivas e a isometria encontradas nas floras tropicais e extra-tropícats em relação ao crescimento da biomassa floral apontam para a presença e desenvolvimento de características sexuais secundarias como importantes ferramentas na permanência e sucesso da reprodução cruzada. Características vegetativas e reprodutivas influenciam na variação interespecífica da biomassa floral e que a função masculina da flor teria forte impacto na evolução das características florais, independentemente da ligação filogenética entre as angiospermas, ressaltando a necessidade de teorias que permitam uma síntese destas relações.
Abstract: Plants are sessile organisms exposed to the effects of environmental stress. The flowers are fundamental structures in the evolution of angiosperms, because through them is sexual reproduction. For this, the flowers exhibit strategies that help the plant to achieve better reproductive success. Animals visit flowers in search of resources, however, to carry pollen between individuals of the same plant species, act as mediators in the process of sexual selection, major force in floral evolution. Ecological factors affecting the relationship between plants atid pollinators may influence the evolution of reproductive strategies of species. Abiotic factors, spatial distribution, population size and life history of plants can modify the abundance and distribution of resources for pollinators by changing patterns of pollen transfer, gene flow and selective pressures responsible for floral evolution. This work seeks to understand the diversity of reproductive strategies in different tropical vegetation types, the modulated vegetative and reproductive features of plants and the abiotic environment in resource allocation as well, check for consistency biogeographical of allometric patterns in reproductive strategies in relation to plants. The study was conducted in areas of tropical vegetation, with an area of Atlantic Rain Forest, an area of Savannah, both in the state of Sao Paulo and an area of Campo Rupestre, in the state of Minas Gerais, allowing the comparison of variation among floral biomass the three vegetation types and between tropical angiosperm morphological peculiarities related to the areas of collection and bibliographic data of extra-tropical species. The richness of plant forms and environments in tropical acts in modulating the interaction between plants and pollinators, influencing the variation of biomass in the floral and vegetative and reproductive characteristics of species. The positive allometry and isometry floras found in tropical and extra-tropical growth over the floral biomass indicate the presence and development of secondary sexual characteristics as important tools in the permanence and success of cross-breeding. Vegetative and reproductive characteristics influence the interspecific variation of floral biomass and that the function of male flowers have a strong impact on the evolution of floral traits, regardless of the phylogenetic connection between the angiosperms, highlighting the need for theories that allow a synthesis of these relationships.
Doutorado
Ecologia
Doutor em Ecologia
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Valverde-Barrantes, Oscar Jesus. "A phylogenetic perspective on fine root ecology: assessing the role of root evolution on fine root functional traits and ecological interactions in woody angiosperms." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1384641579.
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Nohra, Youssef A. "Résines végétales actuelles et fossiles : origine, caractérisation chimique et évolution." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S165.
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Les travaux de cette thèse portent sur la caractérisation chimique des ambres provenant de plusieurs gisements d’âges et d’origines géographiques variés, dont certains sont inédits. Des protocoles identiques à tous les échantillons et combinant les analyses spectroscopiques (IR et RMN 13C) et chromatographiques (THM-CPG-SM) ont été appliqués, permettant d’identifier l’origine botanique des ambres et fournissant des indices pour la reconstitution des paléoenvironnements terrestres. La caractérisation chimique des gisements d’ambre du Jurassique supérieur (Kimméridgien) jusqu’au Crétacé supérieur (Santonien) du Liban, de Jordanie, du Congo, d’Equateur et de France, permet de proposer des biomarqueurs pour les résines de Cheirolepidiaceae, une famille exclusivement mésozoïque de Conifères. Une évolution des sources botaniques des résines produites durant le Mésozoïque et le Cénozoïque est alors discutée. Une production dominée par les familles de Conifères Araucariaceae et Cheirolepidiaceae est remarquée au Jurassique supérieur et Crétacé inférieur. La production au Crétacé supérieur est plutôt dominée par des Cupressaceae. Au Cénozoïque, les origines botaniques des ambres sont plus variées, et des familles d’Angiospermes sont à l’origine de nombreux gisements, dont l’ambre du Pérou produit par une Fabaceae. La production par des Conifères reste toutefois importante au Tertiaire, à l’exemple des ambres de Nouvelle-Zélande qui ont pour origine les Araucariaceae. Les données obtenues ont permis une ré-évaluation de la classification des ambres par Py-GC-MS. Ainsi, une nouvelle molécule dont la structure est inconnue encore, a été identifiée dans les chromatogrammes d’ambres de classe Ib et Ic, ajoutant un caractère discriminant entre ces deux sous-classes. Enfin, la relation âge / maturation des résines fossiles est discutée, qui dépend avant tout des conditions d’enfouissement des résines. Une large base de données moléculaires est ainsi établie pour un grand nombre de gisements d’âges et d’origines botaniques variés, qui permettra une comparaison globale dans les travaux futursThis work focuses on the chemical characterisation of amber from different outcrops from different localities, and varied ages. Some of these outcrops had never been studied. All the amber samples were analysed with the same analytical techniques. The combination of the data obtained from spectroscopic (IR and 13C NMR) and chromatographic (THM-GC-MS) analysis allows the identification of the botanical origin of the amber and provide some information, for the reconstruction of the palaeoenvironment. Biomarkers for the cheirolepidiaceous resins were proposed based on the chemical characterisation of different amber outcrops dating from the Upper Jurassic (Kimmeridgian) to the Upper Cretaceous (Santonian) from Lebanon, Jordan, Congo, Ecuador and France. The Cheirolepidiaceae familt was exclusively present in the Mesozoic era. Hence, the evolution of the botanical origins of the produced resins during the Mesozoic and Cenozoic eras was discussed. It seems that Araucariaceae and Cheirolepidiaceae were the dominant resin producing trees during the Upper Jurassic and the Lower Cretaceous. While, cupressaceous resiniferous plants were dominant during the Upper Cretaceous. Howerver, resins dating from the Cenozoic era, were produced by a wider variety of plants, as resiniferous families of Angiosperm intensively participated in the resin production, i.e. the Peruvian amber produced by Fabaceae. Conifer resins traces were also detected in the Tertiary, such as the amber from the Araucariaceae found in New Zealand. The obtained data allowed a re-evaluation of the classification of ambers by Py-GC-MS, leading to the discovery of a novel molecule. This molecule of an unknown structure brings a new discrimination factor between the classes Ib and Ic. Finally, the age / maturity relationship is showed to be dependent on the burial and the conservation conditions of the resins. A broad molecular database is established based a large group of amber outcrops from different ages, and having diverse botanical origins. This database could be used as a comparative platform for further work in the future
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Debastiani, Vanderlei Julio. "Estrutura filogenética de comunidades de plantas lenhosas em ecótonos vegetacionais." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/69737.
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A busca de padrões consistentes na natureza tem sido a principal meta dos ecólogos. Essa dissertação teve como objetivo usar abordagens filogenéticas na tentativa de compreender melhor o processo ecológico da expansão florestal sobre áreas abertas. O uso da informação filogenética em análises ecológicas considera as espécies não independentes umas das outras, pois estas compartilham grande parte da história evolutiva. Essa hierarquia de organização das espécies é muito importante para determinar as regras que governam os processos de montagem das comunidades locais. Nesta dissertação foram avaliados padrões filogenéticos de estruturação da vegetação lenhosa florestal ocorrente em ecótonos de áreas abertas com vegetação florestal distribuídos em diferentes regiões do extremo sul do Brasil. Estes ecótonos são formados por diversas formações florestais, as quais tendem a expandir sobre as áreas abertas. Dados sobre composição de espécies provieram de estudos já realizados e de amostragens em alguns sítios. Duas métricas filogenéticas complementares foram usadas para avaliar a estrutura filogenética em cada categoria de habitat nos ecótonos: índice de parentesco líquido (NRI) e coordenadas principais da estrutura filogenética (PCPS). As análises dos valores de NRI não mostraram um padrão nítido de estruturação filogenética das comunidades. Já a análise dos PCPS mostrou padrões consistentes nas três escalas espaciais abordadas e independente da composição de espécies. Clados basais associaram-se às áreas florestais, enquanto clados de diversificação recente associaram-se às áreas abertas. Estes resultados indicam que áreas abertas atuam como um filtro filogenético de habitat para as espécies lenhosas florestais em todos os locais analisados, independentemente da escala e da composição de espécies de cada local. Os resultados sugerem que os clados de Rosanae e Asteranae estão na linha de frente do processo de expansão florestal sobre as áreas abertas, e o clado de Magnolianae restrito às áreas florestais. A busca por padrões gerais de organização das comunidades ecológicas a partir de sua estrutura filogenética parece consistir numa ferramenta útil para a exploração e entendimento sobre o funcionamento de sistemas ecológicos. Estas abordagens poderiam beneficiar estratégias de gerenciamento e conservação destes sistemas, por simplificarem sistemas ecológicos complexos e por mostrarem padrões gerais independentes da escala espacial analisada.The search for consistent patterns in nature has been a major goal of ecologists. This study aimed to employ phylogenetic analyses to improve the understanding of an ecological process, the expansion of forest expansion over open areas. The use of evolutionary information considers species as not independent units in relation to each other, as they share their evolutionary history. Such hierarchical organization of species is very important to determine the rules governing assembly processes in local communities. Phylogenetic approaches were used to evaluate phylogenetic patterns in forest woody vegetation occurring in ecotones comprising open areas and forest vegetation, and distributed across different regions in the southernmost Brazilian region. Those ecotones are composed by different forest vegetation types, which tend to expand over open areas. Data on species composition were compiled from previous studies, and vegetation sampling was carried out in sites without available information on species composition in ecotones. Two complementary phylogenetic metrics were used to evaluate the phylogenetic structure in each habitat type occurring in ecotones: net relatedness index (NRI) and principal coordinates of phylogenetic structure (PCPS). Analyses of NRI values did not show any clear pattern of phylogenetic structuring of the communities. Nonetheless, PCPS analysis showed consistent patterns across the threes spatial scales evaluated, which were independent of the species composition of the sites. Basal clades were associated with forest areas, while late-divergence clades were associated with open areas. These findings indicate that open areas act as a phylogenetic habitat filtering to forest woody species throughout the region, independently of the spatial scale and of the species composition in each site. The results suggest that the clades Rosanae and Asteranae represent the vanguard in theforest expansion process over open areas, while the distribution of the basal clade Magnolianae is restricted to forest sites. The search for general organization patterns in ecological communities based on their phylogenetic structure seems to be a useful tool for exploring and understanding the functioning of ecological systems. Such approach might benefit ecosystem managing and conservation strategies, as it simplifies complex ecological systems, and shows general patterns independently of the scale analyzed.
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Barniske, Anna-Magdalena. "Mutational dynamics and phylogenetic utility of plastid introns and spacers in early branching eudicots." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-26261.
Full textAbstract:
Major progress has been made during the last twenty years towards a better understanding of the evolution of angiosperms. Early molecular-phylogenetic analyses revealed three major groups, with eudicots as well as monocots being monophyletic, arisen from a paraphyletic group of dicotyledonous angiosperms (= basal angiosperms). Consistently, numerous phylogenetic studies based on sequence data have recovered the eudicot-clade and increased confidence in its existence. Furthermore this clade, which contains about 75% of angiosperm species diversity, is characterized by the possession of tricolpate and tricolpate-derived pollen and has thus also been called the tricolpate clade. Based on molecular-phylogenetic investigations several lineages, such as Ranunculales, Proteales (= Proteaceae, Nelumbonaceae, Platanaceae), Sabiaceae, Buxaceae plus Didymelaceae, and Trochodendraceae plus Tetracentraceae were shown as belonging to a early-diverging grade (early-diverging or “basal” eudicots), while larger groups like asterids, Caryophyllales, rosids, Santalales, and Saxifragales were identified as being members of a highly supported core clade, the so called “core eudicots”. Nevertheless, phylogenetic relationships among several lineages of the eudicots remained difficult to resolve. This thesis is mainly concentrated on fully resolving the branching order among the different clades of the early-diverging eudicots as well as on clarifying phylogenetic and systematic conditions within several lineages, based on phylogenetic reconstructions using sequence data of rapidly-evolving and non-coding molecular regions, such as spacers and introns. Commonly, fast-evolving and non-coding DNA was used to infer relationships among species and genera, as practised in chapter 3, due to the assumption of being inapplicable caused by putative high levels of homoplasy through multiple substitutions and frequent microstructural changes resulting in non-alignability. However, during the last few years numerous molecular-phylogenetic studies were able to present well resolved angiosperm trees on the basis of rapidly-evolving and non-coding regions from the large single copy region of the chloroplast genome comparable to multi-gene analyses concerning topology and statistical support. Mutational dynamics in spacers and introns was revealed to follow complex patterns related to structural constraints like the introns secondary structure. Therefore extreme sequence variability was always confirmed to mutational hotspots that could be excluded from calculations. Moreover it became clear that combining these non-coding regions with the fast-evolving matK gene can lead to further resolved and statistical supported trees.
Chapter 1 deals with the placement of Sabiales inside the early-diverging eudicot grade, while investigating mutational dynamics as well as the utility of different kinds of non-coding and rapidly-evolving DNA within deep-level phylogenetics. It was done by analyzing a combination of nine regions from the large single copy region of the chloroplast genome, including spacers, the sole group I intron, three group II introns and the coding matK for a sampling of 56 taxa. The presented topology is in mainly congruence with the hypothesis on phylogenetic relationships among early-branching eudicots that was gained through the application of a reduced set of five non-coding and fast-evolving molecular markers, including the plastid petD (petB-petD spacer, petD group II intron) plus the trnL-F (trnL group I intron, trnL-F spacer) region and the matK gene. It showed a grade of Ranunculales, Sabiales, Proteales, Trochodendrales and Buxales. The current study differs in showing Sabiales as sister to Proteales in all phylogenetic analyses, in contrast to a second-branching inside early-diverging eudicots and a Bayesian tree displaying Sabiales branching after Proteales. All three hypotheses were tested concerning their likelihood. None of them was shown as being significantly declinable. Thus, albeit the number of characters and informative sites was doubled in comparision to the five-region investigation, the exact position of the Sabiales remained to be resolved with confidence. However, the advanced analyses of the phylogenetic structure of the three different non-coding partitions in comparison to coding genes resulted in the recognition of a significantly higher mean phylogenetic signal per informative character within spacers and introns than in the frequently applied slowly-evolving rbcL gene. The fast-evolving and well performing matK gene is shown to be nested within the non-coding partitions in this respect. Interestingly, the least constrained spacers displayed considerably less phylogenetic structure than both, the group I intron and the group II introns. Molecular evolution is again shown to follow certain patterns in angiosperms, as indicated by the occurrence of mutational hotspots and their connection to structural and functional constraints. This is especially shown for the group II introns studied where highly dynamic sequence parts were rather found in loops than stems.
The aim of chapter 2 was to present a comprehensive reconstruction of the phylogenetic relationships inside the order of Ranunculales, the first-branching clade of the early-diverging eudicots, with an emphasis on the evolution of growth forms within the group. Currently, the order comprises seven families (Ranunculaceae, Berberidaceae, Menispermaceae, Lardizabalaceae, Circaeasteraceae – not included due to lacking plant material, Eupteleaceae, Papaveraceae) containing predominantly herbaceous groups as well as trees and lianescent/shrubby forms. A surprising result that emerged due to the increased use of molecular data within systematics during the last twenty years is the inclusion of the woody Eupteleaceae into Ranunculales. Because of its adaptation to wind pollination it was previously placed next to Hamamelididea. Although phylogenetic hypotheses agreed in the exclusion of Eupteleaceae and the predominantly herbaceous Papaveraceae from a core clade the branching order within early-diverging Ranunculales remained a question to be answered. Thus phylogenetic reconstructions based on molecular data of 50 taxa (including outgroup), applying the well-performing non-coding petD and trnL-F as well as the trnK/matK-psbA region including the coding matK, were carried out. The comprehensive sampling resulted in fully resolved and highly supported phylogenies in both, maximum parsimony and model based approaches, with family relations within the core clade being identical and Euptelea appearing as first branching lineage. However, the relationships among the early-diverging Ranunculales could not be resolved with confidence, a result in line with the finding made in chapter 1. The topology was further resolved as Lardizabalaceae being sister to the remaining members of the order, followed by Menispermaceae, Berberidaceae and Ranunculaceae, the latter sharing a sistergroup relationship. Inside the mainly lianescent Lardizabalaceae the shrubby Decaisnea was clearly depicted as first-branching. The systematic controversial Glaucidium and Hydrastis are shown to be early-diverging members of the Ranunculaceae.
A central goal of chapter 3 was to test phylogenetic relationships among the members of the ranunculaceous tribe Anemoneae. Currently it consists of the subtribes Anemoninae including Anemone, Hepatica, Pulsatilla and Knowltonia, and Clematidinae, consisting of Archiclematis, Clematis and Naravelia. Furthermore the position and taxonomic rank of several lineages inside the subtribe Anemoninae were examined. Since recent comprehensive molecular-phylogenetic investigations have been carried out for the members of Clematidinae or Anemoninae, 63 species representing all major lineages of the two subtribes were included into analyses. Calculations were carried out on the basis of molecular data of the nuclear ribosomal ITS1&2 and the plastid atpB-rbcL intergenic spacer region. Phylogenetic reconstructions resulted in the recognition of two distinct clades within the tribe, thus corroborating the formation of the two subtribes. Within the subtribe Anemoninae the traditional genera Knowltonia, Pulsatilla and Hepatica are confidently shown to be nested within the genus Anemone. The preliminary classification of the genus, currently consisting of the two subgenera Anemone and Anemonidium, is complemented by the subgenus Hepatica.