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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Atividade larvicida do extrato bruto de Swinglea glutinosa evidenciada pelas alterações morfohistológicas em larvas de Aedes aegypti (Diptera, Culicidae) / Larvicidal activity of crude extract of Swinglea glutinosa shown by morphohistological in larvae Aedes aegypti (Diptera, Culicidae)

Cabral, Sávio da Silva 29 June 2015 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-12-01T08:08:44Z No. of bitstreams: 2 Dissertação - Sávio da Silva Cabral - 2015.pdf: 9714568 bytes, checksum: f7d378786c6256c4c799baf29e381ad4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-12-01T08:12:06Z (GMT) No. of bitstreams: 2 Dissertação - Sávio da Silva Cabral - 2015.pdf: 9714568 bytes, checksum: f7d378786c6256c4c799baf29e381ad4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-12-01T08:12:06Z (GMT). No. of bitstreams: 2 Dissertação - Sávio da Silva Cabral - 2015.pdf: 9714568 bytes, checksum: f7d378786c6256c4c799baf29e381ad4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-06-29 / Aedes aegypti is the major vector of dengue, urban yellow fever and emerging arboviruses in Brazil, as chikungunya fever. This mosquito is adapted to the urban environment, and is an important factor for the maintenance of its kind, the long period of quiescence of eggs, which was an extraordinary physiological adaptation to different climatic and dietary factors. Approximately 2.5 billion people live in endemic, exposed to dengue transmission countries. The best solution would be to control multivalent vaccines to existing serotypes. Tetravalent vaccines are being tested in several countries, including Brazil. However, recently it described a fifth serotype, and this can probably extend the course of research. So how vaccines are not ready for use, dengue control has been done by the intervention of actions against the vector, Ae. aegypti. Among the actions, the use of synthetic chemical insecticides has been the main, it emerged mosquito susceptibility of modification in many Brazilian cities and later confirmation of resistance status. This paper proposes the search for alternatives, through prospecting of natural compounds insecticides for the control of Ae. aegypti. Among the actions, the use of synthetic chemical insecticides has been the main. However, with the continuous use of the same product in some brazilians municipalities seemed evidence of mosquito susceptibility modification and subsequently confirm the resistance status. Among, measures control alternatives Ae. aegypti is prospecting for natural compounds insecticides. This work proposes the study of crude ethanol extract (c.e.e.) the result of Swinglea glutinous as larvicide and it showed CL50 and CL90 of 74.4 ppm to 125.2 ppm for third instar larvae of Ae. aegypti, besides the toxicity effect on these intestinal cells larvae investigated by morphohistological study. The morphological changes that are intensified with increasing time of exposure to the larvae of c.e.e. were visualized particularly in the posterior region of the midgut, included folding of the peritrophic matrix, increasing subperitrophic space, cytoplasmic vacuolization, reduction of the microvilli cells. What characterized and checked the larvicidal effect of c.e.e. demonstrating its potential use for controlling Ae. aegypti. / Aedes aegypti é o principal vetor de dengue, da febre amarela urbana e arboviroses emergentes no Brasil, como a febre chikungunya. Esse mosquito encontra-se adaptado ao ambiente urbano, e tem como importante fator para a manutenção de sua espécie, o longo período de quiescência dos ovos, que foi uma extraordinária adaptação fisiológica aos diferentes fatores climáticos. Aproximadamente 2,5 bilhões de pessoas vivem em países endêmicos, expostos à transmissão de dengue. A melhor solução para o controle seria vacinas plurivalentes para os sorotipos existentes. Vacinas tetravalentes estão sendo testadas em vários países, incluindo o Brasil. Recentemente, foi descrito um quinto sorotipo, e isto provavelmente pode ampliar o curso da pesquisa. O controle de dengue, ainda tem sido feito pela intervenção de ações contra o vetor, Ae. aegypti. Dentre as ações, o uso de inseticidas químicos sintéticos tem sido a principal. Porém, com o uso contínuo do mesmo produto, em alguns municípios brasileiros apareceram indícios da modificação da suscetibilidade do mosquito e, posteriormente, a confirmação do status de resistência. Dentre medidas alternativas de controle de Ae. aegypti está a prospecção de compostos naturais inseticidas. Este trabalho propões o estudo do extrato bruto etanólico (e.b.e.) do fruto de Swinglea glutinosa como larvicida e este apresentou CL50 de 74,4 ppm e CL90 de 125,2 ppm para larvas de terceiro estádio de Ae. aegypti, além do efeito de toxicidade em células do intestino dessas larvas, investigados por meio de estudo morfohistológico. As alterações morfológicas que se intensificavam com o aumento do tempo de exposição das larvas ao e.b.e., foram visualizadas principalmente na região posterior do mesêntero, incluía o dobramento da matriz peritrófica, o aumento do espaço subperitrófico, vacuolizações citoplasmáticas, diminuição das microvilosidades das células. O que caracterizou e comprovou o efeito larvicida do e.b.e., demonstrando seu potencial uso para o controle de larvas de Ae. aegypti.
2

Kinematics and Hydrodynamics of Undulatory Locomotion in Hagfishes (Myxinidae) and Hagfish-like Robotic Models

Lim, Jeanette Li Li 30 September 2013 (has links)
Hagfishes have both intrigued and confused biologists since Linnaeus first mistakenly classified one as an "intestinal worm." Modern hagfishes (Myxinidae) are elongate, marine fishes often described by what they lack: jaws, scales, paired fins, or a vertebral column. Accompanying this reduced morphology was a long-held view that hagfish are lazy animals that mostly lay about on the ocean floor, but more recent research has revealed them to be active hunters and scavengers in the benthic community. Routine swimming is a requisite part of these activities, yet knowledge of how these exceptionally flexible fishes swim is limited. Here, I use an integrative experimental approach to provide a more comprehensive, quantitative understanding of locomotory mechanisms in hagfishes. In Chapters 1 and 2, I use high-speed videography to quantify whole-body kinematics of steady and unsteady swimming in Eptatretus stoutii and Myxine glutinosa, representing the two main lineages within Myxinidae. Both species generally swim with high amplitude head movements and use tail beat frequency to control swim speed, but inter- and intra-specific variation in other undulatory wave variables suggests multiple mechanisms to modulate speed. Changes in the shape of the body wave characterize the observed unsteady swimming behaviors. During positive linear accelerations, hagfish transiently adopt a larger, longer body wave. During lateral maneuvers, hagfish approximate “sidewinding” behavior as anterior body regions interact with the substrate while posterior body regions propagate waves of lateral bending toward the tail tip. Chapter 3 integrates kinematics with hydrodynamics, using particle image velocimetry to visualize the flow field around swimming E. stoutii. The steady swimming wake consists of caudolateral fluid jets, which turn caudally during linear accelerations. Wake jets orient asymmetrically during lateral swimming, contributing both forward and lateral thrust over a complete tail beat. The hydrodynamic patterns observed reinforce kinematics-based hypotheses on how hagfishes enact their various swimming behaviors. In Chapter 4, I use simple robotically-controlled physical models to examine functional relationships between body flexural stiffness, shape, kinematics, hydrodynamics, and swimming performance. I relate model swim performance to characteristics of hagfish swimming, and describe lessons that passively undulating models impart for understanding locomotion by live elongate undulatory swimmers.
3

Huanglongbing e Diaphorina citri: estudos das relações patógeno-vetor-hospedeiro / Huanglongbing and Diaphorina citri: studies on pathogen-host-vector interactions

Cifuentes Arenas, Juan Camilo [UNESP] 26 June 2017 (has links)
Submitted by JUAN CAMILO CIFUENTES ARENAS null (jccifuen@gmail.com) on 2017-08-20T22:26:16Z No. of bitstreams: 1 Tese_Juan_Camilo_Cifuentes_Arenas.pdf: 3235857 bytes, checksum: 09f86c9212a38b12988810c2eb30b9c0 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-24T12:32:17Z (GMT) No. of bitstreams: 1 cifuentesarenas_jc_dr_jabo.pdf: 3235857 bytes, checksum: 09f86c9212a38b12988810c2eb30b9c0 (MD5) / Made available in DSpace on 2017-08-24T12:32:17Z (GMT). No. of bitstreams: 1 cifuentesarenas_jc_dr_jabo.pdf: 3235857 bytes, checksum: 09f86c9212a38b12988810c2eb30b9c0 (MD5) Previous issue date: 2017-06-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O huanglongbing (HLB), associada a bactérias de floema (Candidatus Liberibacter spp) transmitidas por insetos (Diaphorina citri), é a doença mais destrutiva dos citros e muitos têm sido os esforços visando reduzir sua disseminação nos pomares, porém, nem sempre bem-sucedidos. Somente no cinturão citrícola paulista mais de 45 milhões de plantas já foram erradicadas por causa do HLB. O objetivo deste trabalho foi investigar diferentes aspectos associados ao patossistema HLB, visando trazer informações que ajudem na contenção da doença. Foram estudados: 1) hospedeiros alternativos do inseto vetor e do patógeno; 2) ontogenia do broto vegetativo de citros e seu potencial em multiplicar D. citri; 3) requerimentos térmicos para o desenvolvimento do broto; e 4) influência do porta-enxerto na biologia de D. citri. No primeiro capítulo é apresentada revisão de literatura sobre os aspectos mais relevantes da citricultura e do patossistema em estudo e, nos demais, os resultados das pesquisas. No segundo é apresentada a importância Swinglea glutinosa (rutácea muito comum em certas regiões citrícolas) como fonte de Ca. Liberibacter asiaticus e criadouro de D. citri. A bactéria do HLB multiplicou na planta, porém atingiu populações consideravelmente menores do que em laranjeira ‘Valência’. Apresenta, portanto, baixo potencial como fonte de inóculo para os citros. Por outro lado, D. citri reproduziu abundantemente em S. glutinosa, tanto quanto nas principais variedades de laranjeiras doces e limoeiros do grupo ‘Siciliano’ cultivados no Brasil. No terceiro capítulo são apresentados detalhes do desenvolvimento do broto em laranjeira ‘Valência’ e como os diferentes estádios influenciam o potencial biótico de D. citri. O inseto completou seu ciclo de vida em todos os estádios, mas em diferentes intensidades, sendo maiores nos estádios iniciais. Com os dados criou-se um índice de favorabilidade à reprodução do inseto, que leva em consideração o peso relativo de cada estádio do broto na biologia do inseto. No quarto capítulo é apresentado o impacto da temperatura do ar sobre o broto, o que permitiu determinar os graus-dia necessários ao seu desenvolvimento (GDD) e, com base no GDD, estabelecer um modelo geral inovador de previsão de pulverizações. No quinto capítulo é demonstrado que o porta-enxerto (limoeiro Cravo, tangerineira Sunki e citrumeleiro Swingle), por mecanismos de antibiose e/ou antixenose, afetam D. citri. Mas esses fenômenos ocorrem somente na fase de seedlings, e nas copas neles enxertadas somente enquanto a planta é jovem (muda). Em plantas adultas, de maior porte, tais fenômenos não foram detectados. Podem ter sido mascarados por influência da variedade copa (laranjeira). / Huanglongbing (HLB), associated with insect-borne phloem bacteria (Candidatus Liberibacter spp), is the most destructive disease of citrus and many efforts have been made to reduce its spread in orchards, but not always well-succeeded. Only in the citrus belt of São Paulo state (Brazil), more than 45 million plants have already been eradicated because of HLB. The objective of this work was to investigate different aspects associated to the HLB pathosystem, aiming to bring information that helps in the management of the disease. We studied: 1) alternative vector insect and pathogen hosts; 2) ontogeny of the citrus vegetative shoot and its potential to multiply D. citri; 3) thermal requirements for shoot development; and 4) influence of the rootstock on the biology of D. citri. In the first chapter, a literature review on the most relevant aspects of citriculture and pathosystem in study is presented and, in the others, the results of the experiments. In the second one the importance of Swinglea glutinosa (a Rutaceae very common in certain citrus regions) as a source of Ca. Liberibacter asiaticus and host for D. citri is presented. The HLB bacteria multiplied in the plant, but reached populations considerably smaller than in 'Valencia' sweet orange. Therefore, it presents low potential as a source of inoculum for citrus. On the other hand, D. citri reproduced abundantly in S. glutinosa, as well as in the main sweet orange and lemon varieties of the 'Sicilian' group cultivated in Brazil. In the third chapter, it is presented details of the development of the 'Valencia' orange new shoot and how the different stages influence the biotic potential of D. citri. The insect completed its life cycle at all stages of new shoots, but at different intensities, being larger in the early stages. With the data, an insect reproduction index was created, which takes into account the relative weight of each shoot stage in the insect biology. In the fourth chapter, it is presented the impact of the air temperature on the shoot, which allowed to determine the degree-days required for its development (GDD) and, based on the GDD, to establish an innovative general model of spray forecasting. In the fifth chapter it is demonstrated that the rootstock (‘Rangpur’ lime, ‘Sunki’ mandarin and ‘Swingle’ citrumelo), by mechanisms of antibiosis and / or antixenosis, affect D. citri. But these phenomena occur only in the stage of seedlings, and in the scions grafted on them only while the plant is young (nursery tree). In larger adult plants, such phenomena were not detected. They may have been masked by the influence of the scion (orange) variety.
4

Thorium jako environmentální stresový faktor pro růst rostlin v kontaminovaném prostředí / Thorium as an environment stressor for plant growth.

Hrdinová, Aneta January 2016 (has links)
Thorium is an element belonging to heavy metals, which is characterized by its radioactivity similarly to uranium and radon. Thorium is not commonly used in industry, but becouse of its radioactive properties it has a great potentional for future use in nuclear energetics. Thus, increasing release of Th into the soil, water and atmosphere can be expected in near future and through plant biomass it could become a part of food chains and webs and, thus, to represent a considerable health risks to humans. Studies devoted to research on thorium and its effects on plants has not been published much yet. The majority of these studies focus mainly only on plant abilities to accumulate thorium and/or monitoring distribution of thorium in plant body. But till now, a study is still missing, which would monitor the effect of thorium on the physiological characteristics of plants. Plants of Nicotiana glutinosa (L.) medium Thorium accumulatin were hydroponically cultivated Hoagland nutrient media differedin the presence of thorium, tartaric acid, putrescine and phosphates. In first part of the present study I monitored accumulation of thorium by tobacco plants under the influence of the above-mentioned modifications of media. In the second part, I studied the Th effect on the photosynthetic apparatus (contents...
5

Wechselwirkung zwischen Schwarzerlen und Erlenblattkäfer: Signaltransfer zwischen Bäumen und induzierte Resistenz / Relationship between black alders and black alder leaf beetle: interplant signal transfer and induced resistance

Thiessen, Sabine 01 November 2001 (has links)
No description available.
6

Estudo de Determinação Cromatográfica e Avaliação das Atividades Antifúngica e Anti-hipertensiva de Extratos Obtidos de Cuphea Glutinosa Cham. & Schltdl (lythraceae) / Study of Chromatographic Determination and Evaluation of the Antifungal and Antihypertensive Activities of Extract S Obtained from Cuphea Glutinosa Cham . & Schltdl (lythraceae)

Santos, Marí Castro 17 July 2014 (has links)
Submitted by Sandro Camargo (sandro.camargo@unipampa.edu.br) on 2015-05-08T02:43:19Z No. of bitstreams: 1 127110045.pdf: 1527824 bytes, checksum: 960729a0a23069d5d40ec997cc3034b8 (MD5) / Made available in DSpace on 2015-05-08T02:43:19Z (GMT). No. of bitstreams: 1 127110045.pdf: 1527824 bytes, checksum: 960729a0a23069d5d40ec997cc3034b8 (MD5) Previous issue date: 2014-07-17 / O gênero Cuphea, popularmente conhecido no Brasil por “sete-sangrias”, tem seu uso medicinal reconhecido devido aos efeitos diurético, hipotensor e cardioprotetor. No sul do Brasil, em região característica do bioma Pampa, foi encontrada a espécie Cuphea glutinosa Cham. & Schltdl. Embora o uso popular, esta espécie é pouco descrita na literatura. O presente trabalho tem como objetivos o estudo da composição química dos extratos de C. glutinosa e a avaliação das atividades antifúngica e anti-hipertensiva. O material vegetal foi coletado na cidade de Uruguaiana (RS, Brasil), identificado e depositado em herbário. Após secagem e trituração do material vegetal, foram obtidos os extratos hidroetanólicos através de maceração exaustiva com etanol 40% (v/v) para folhas e etanol 70% (v/v) para raízes. Para a infusão, utilizou-se água a 80oC. As análises cromatográficas foram realizadas em equipamento cromatógrafo a líquido Prominence Shimadzu, em técnica por CLAE e CLUE. Utilizou-se sistema de fase reversa, eluição por gradiente com fase móvel composta por acetonitrila:metanol (4:1) e ácido fórmico 0,1% pH 3,0, coluna C18 analítica e fast, e detecção por UV-DAD e ESI-MS. Os teores de polifenóis totais e de flavonóides foram determinados por método colorimétrico, seguindo metodologia padronizada. A atividade antifúngica in vitro foi realizada utilizando o método de microdiluição em caldo, determinando-se a CIM, in-vitro, contra diferentes isolados clínicos. Para avaliação do potencial anti-hipertensivo in vivo, foram realizadas medições da pressão sanguínea pelo método de monitoramento hemodinâmico invasivo, através da inserção de cateter na artéria carótida. Os resultados de teor de fenólicos totais indicaram predominância destes componentes em extratos obtidos de folhas e por maceração, conforme os valores obtidos: 1,8501 mg EAG/mL (folhas) e 0,8467 mg EAG/mL (raízes) para infusão, e 3,7284 mgEAG/mL (folhas) e 2,6266 mg EAG/mL (raízes) para maceração. Quanto ao teor de flavonóides, os resultados quantitativos foram: 7,0959 mg/g (folhas) e 0,5664 mg/g (raízes) para a infusão, e 7,9511 mg/g (folhas) e 0,5994 mg/g (raízes) para maceração. Na análise cromatográfica, os extratos obtidos das folhas de C. glutinosa apresentaram picos cromatográficos bem separados, em perfil reprodutível. Na determinação por CLUE-MS, os dados de íon molecular e fragmentos de massa indicaram a composição predominante em flavonóides, sugerindo-se os componentes quercetina-3-O-glicosídeo, quercetina-3- arabinosídeo, quercetina-3-glicuronídeo, isoramnetina e quercetina-5-O-β-glicopiranosídeo. Para o potencial antifúngico, os extratos das folhas e raízes apresentaram atividade in vitro contra Candida parapsilosis, Candida tropicalis e Trichosporon asahii, com CIM variando na faixa de 1,9-62,5 μg/mL. Nos testes hemodinâmicos realizados, os extratos das folhas não apresentaram efeito significativo sobre a pressão arterial. A identificação dos componentes em C. glutinosa, derivados de quercetina, torna promissora novas investigações a fim de aprofundar o conhecimento a respeito desta espécie, em especial na busca de respostas para a relatada ação anti-hipertensiva. / The Cuphea genus, popularly known in Brazil as "sete-sangrias", is used traditionally due the diuretic, hypotensive and cardioprotective effects. In southern Brazil, in characteristic region of Pampa biome, it was found the species Cuphea glutinosa Cham. & Schltdl. Although used popularly, this species is few reported in the literature. The present work aimed to study the chemical composition of extracts from C. glutinosa and to evaluate the antifungal and anti -hypertensive activities. The plant material was collected in the city of Uruguaiana (RS, Brazil), identified and deposited in a herbarium. After dryness and milling, the hydroethanolic extracts were obtained through exhaustive maceration using ethanol 40% (v/v) for leaves and ethanol 70% (v/v) for roots. The infusions were prepared using water at 80 °C. The chromatographic analyses were performed in liquid chromatography Prominence Shimadzu, for HPLC and UPLC assays. The method was conducted using reverse phase system, gradient elution with mobile phase composed by acetonitrile:methanol (4:1) and formic acid 0.1% pH 3.0, C18 analytical and fast column, and detection by UV-DAD and MS. The polyphenols and flavonoids contents were determined by colorimetric method. The in vitro antifungal activity was conducted by using the broth microdilution method, determining the MIC against different clinical isolates. For evaluation of in vivo anti-hypertensive potential, the blood pressure was measured by the method of invasive hemodynamic monitoring, through of insertion the catheter into the carotid artery. The results of phenolic content indicated the high concentration of these compounds in leaves extracts obtained by maceration: 1.8501 mgEAG/mL (leaves) and 0.8467 mgEAG/mL (roots) for infusion, and 3.7284 mgEAG/mL (leaves) and 2.6266 mgEAG/mL (roots) for maceration. For flavonoids, the contents were: 7.0959 mg/g (leaves) and 0.5664 mg/g (roots) for infusion, and 7.9511 mg/g (leaves) and 0.5994mg/g (roots) for maceration. In the chromatographic analyses, the leaf extracts from C. glutinosa presented chromatographic peaks well separated and reproducible. In the determination by UPLC-MS, the molecular ion and mass fragments indicated the predominant composition in flavonoids, suggesting the compounds quercetin-3- O-glucoside, quercetin-3-arabinoside, quercetin-3-glucuronide, isorhamnetin and quercetin-5- O-β-glucopiranoside. For the antifungal potential, the leaf and roots extracts presented activity against Candida parapsilosis, Candida tropicalis e Trichosporon asahii, with MIC values ranging 1,9-62,5 μg/mL. In the hemodynamic tests performed, the leaves extracts did not present significant effect in the arterial pressure, although a tendency in pressure reduction could be observed. The identification of quercetin derivatives in C. glutinosa becomes promisor further investigations about this species, mainly in respect to the anti-hypertensive action.
7

Ecological integrity of boreal streams : assessing impacts on community structure and function /

Bergfur, Jenny, January 2007 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.
8

Symbiotic relationships of Alnus glutinosa with arbuscular mycorrhizal fungi and with Frankia

Orfanoudakis, Michail January 2003 (has links)
The occurrence in Scotland of arbuscular mycorrhizal fungi (AMF) infective on Alnus glutinosa and the effects on early growth of inoculation of seedlings with AMF and Frankia were investigated. AMF characteristic of G/omiw-like fungi were detected microscopically in A. glutinosa roots from mineral and loam but not from highly organic soils. Both GJomus- and Gigaspora-like fungi were detected only in roots from sandy soils. Glasshouse experiments showed that Glomus and Gigaspora species gave higher colonisation of roots, and were of higher compatibility with the host plant, than Acutelospora or Scutettospora species. Colonisation by AMF increased nodulation by Frankia and vice versa. Inoculation with AMF alone and dual inoculation with Gigaspora rosea and Frankia inhibited growth of young A. glutinosa seedlings. Initially after inoculation, AMF colonisation was poor allowing the host to meet the requirements of both developing symbioses. Mycorrhizal plants inoculated with Frankia 15 days after AMF inoculation, were under significant stress and this delayed the beneficial effects of AMF and Frankia symbiosis. Seedlings compensated for the cost of symbiosis by developing a larger, leafy shoot in a period of 25-30 days after AMF inoculation, with or with out, Frankia nodulation. A significant increase in root length and branching detected after inoculation with AMF and Frankia must impose additional energy requirements. However, the stimulation of lateral root branching that follows AMF colonisation may facilitate nutrient uptake, thus helping the plant to overcome the disadvantages of early retardation of shoot growth. Competition with adjacent plant species for below ground space may also be enhanced thus facilitating competition for growing space with other plant species. These factors may be part of a strategy that assists the survival of very young seedlings in the field. The data obtained suggest that delaying Frankia inoculation for 3-4 weeks after inoculation with selected AMF should improve the production in Scottish nurseries of robust, well nodulated and mycorrhizal seedlings.
9

Landscape genetics of Alnus glutinosa across contrasting spatial scales in a natural river system

Flint, Gillian F. January 2015 (has links)
The genetic diversity and genetic structure of populations, and the processes shaping gene flow within and between populations, are influenced by the landscapes they occur within. Within terrestrial landscapes, rivers and their riparian habitat are among the most dynamic, diverse and complex of landscapes and their linear structure appears as an interlinking feature across large landscapes. This thesis took a landscape genetics approach to examine the influence of river landscape features on Alnus glutinosa populations, a widespread keystone tree species of European riparian ecosystems. By accounting for the differing dispersal mechanisms of A. glutinosa (wind and water), landscape effects on seed- and pollen-mediated gene flow, genetic diversity, demographic and genetic structure were identified at different spatial scales of a large UK river catchment. Widespread gene flow within and between A. glutinosa populations was identified with no apparent limitation of wind-mediated pollen dispersal. Hydrochorous dispersal of seed between populations was evident, and found to increase genetic connectivity between riparian populations; however an isolation by distance effect was identified between populations located further apart from each other. No pattern of genetic diversity was found, with high levels of genetic diversity identified at all spatial and temporal scales. At the river-catchment scale no genetic clustering was observed, either within or between the six rivers studied. Demographic structuring within A. glutinosa populations was evident, and correlated with distance from the main river channel. Interactions between seed dispersal, hydrological disturbance, colonisation, and historical influences are discussed in relation to fine-scale spatial genetic structure between A. glutinosa sapling and adult generations. Central to the landscape genetics approach taken in this thesis was the incorporation of key A. glutinosa life history attributes. By incorporating gene flow analyses, species ecology and landscape features, the research presented here furthers our understanding of riverine landscape influences on their riparian populations at different spatial scales and can be used to inform management principles.
10

Dendrochronologie vybraných autochtonních dřevin na gradientech prostředí / Dendrochronology of representative autochtonnous tree species on environmental and temporal gradients

ČEJKOVÁ, Alžběta January 2012 (has links)
This thesis is focused on application methods of dendrochronology on various ecological and historical aspects of forest communities, human management practices, and historical utilization of wood. Studies revealed growth responses of trees in various type of forest vegetation represented by spruce forest, alder carr and alluvial forests and involved autochthonous tree species with all morphological types of wood. These works demonstrated necessity of dynamic evolving of the regional chronologies for the Czech Republic.

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