• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 65
  • 59
  • 29
  • 5
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 189
  • 189
  • 64
  • 58
  • 40
  • 36
  • 32
  • 32
  • 30
  • 29
  • 24
  • 22
  • 19
  • 19
  • 18
  • 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.
111

Etude de l’impact de l’anthropisation sur l’écologie évolutive des vecteurs de la maladie de Chagas : cas de trois communautés du Tapajos, Amazonie brésilienne / Study of the impact of the anthropisation on the evolutionary ecology of the vectors of the disease of Chagas : the case of three communities of Tapajos, Brazilian Amazonia

Quartier, Marion 14 December 2011 (has links)
Les perturbations anthropiques en Amazonie liées au déboisement de la forêt tropicale conduisent à une mosaïque de paysages constituée de végétations secondaires (forêts secondaires, palmeraies, jachères) et de pâturages. Ces modifications favorisent la prolifération de grands palmiers héliophiles invasifs de la famille Attalea spp., palmiers qui constituent l'écotope principal des espèces de Rhodnius, punaises hématophages vectrices de Trypanosoma cruzi, agent étiologique de la Maladie de Chagas en Amérique Latine. Cette étude a porté sur différentes unités de paysage de trois communautés rurales du bas Tapajós (Amazonie brésilienne) ayant une époque d'installation différente sur le territoire (25-75 ans). Six unités de paysage ont été définies sur le terrain et appliquée via une classification supervisée à une image SPOT 5, afin d'obtenir une cartographie du risque environnemental associé à la présence de palmiers dans la région. Sur les cent trente trois palmiers disséqués appartenant aux trois espèces Attalea maripa, A. phalerata et A.speciosa, 73 (54.88%) étaient infestés par R. robustus (742 insectes récoltés). Des diminutions significatives de densité de triatomes ont été observées chez A. maripa, dans la communauté la plus récemment établie (Araipá) et dans les unités de paysage les plus anthropisées. L'infection des insectes par T. cruzi et T. rangeli a été examinée à l'aide de méthodes moléculaires (mini exon SL_IR and sno-RNA-C11). Respectivement 123 (16.57%) et 69 (9.3%) insectes dans 31 (23.3%) et 17 (13.82%) palmiers ont été identifiés positifs à T cruzi et à T.rangeli. Aucune infection n'a été trouvée dans les insectes collectés à Araipá et aucune différence significative n'a été mise en évidence entre les différentes unités de paysage. Les souches de Trypanosoma cruzi identifiées à l'aide de 4 marqueurs moléculaires (mini exon SL-IR, GPI, HSP60 et D7-24α-rRNA) appartiennent à la lignée TcId et 10 (8.13%) individus présentent une infection mixte TcI-TcII. Vingt espèces d'hôtes réparties en trois classes (mammifères, oiseaux, sauropsidés) ont été identifiées comme sources alimentaires à partir du repas sanguin contenu dans le tube digestif des insectes, à l'aide d'amorces cytochrome b, spécifiques de vertébrés. Quatre-vingts et un pourcent des repas détectés ont été effectués sur des mammifères, hôtes potentiels de T.cruzi dont Tamandua tetradactyla, source alimentaire principale. Cet hôte a été clairement identifié comme réservoir de T.rangeli ainsi que suggéré pour T.cruzi. L'analyse phylogénique réalisée à l'aide de séquences de cytochrome b démontre que les individus de Rhodnius identifiés dans la région du Tapajos appartiennent au clade II, ce qui correspond à une extension de l'aire précédemment décrite pour ce clade. L'utilisation du marqueur mitochondrial cytochrome b a permis de mettre en évidence une structuration phylogénétique (haplogroupes) non retrouvée à l'aide des marqueurs microsatellites. Ce résultat montre que l'histoire des gènes (génome mitochondrial) ne retrace pas l'histoire des individus (microsatellites, 10 locus). L'analyse de génétique des populations conduite à l'aide des deux types de marqueurs n'a pas révélé de structuration génétique au sein de la zone d'étude entre les communautés ou les unités de paysage. Cette étude met en évidence des flux géniques importants peu sensibles à la fragmentation du milieu, la dynamique d'invasion des palmiers assurant aux insectes une connectivité fonctionnelle entre les différentes unités de paysages et les communautés. La prédiction du risque environnemental lié à la situation du Tapajós va vers une augmentation du risque de transmission de la Maladie de Chagas dans cette région, du fait de l'abondance des palmiers, de leur forte connectivité, et de la présence de vecteurs et d'hôtes infectés circulant entre les différentes communautés et unités du paysage / Anthropic disturbances from deforestation of Amazon tropical forest leads to a mosaic of landscapes composed of secondary vegetation (secondary forest, palm groves, fallows) and pasture. These changes result in the proliferation of invasive heliophilous palm trees of the family Attalea spp., the principal ecotope of Rhodnius species, bloodsucking bug vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease in Latin America. The present study focuses on different land cover classes of three rural communities of the lower Tapajós (Brazilian Amazon) with different settlement times (25-75 years). Six different land-cover classes were identified on the field and applied through supervised classification on a SPOT 5 image of the study area in order to cartography environmental risk associated to palm tree presence in the area. Three hundred and thirty palms trees of three species Attalea maripa, A. phalerata and A.speciosa were dissected of which 73 (54.88%) were infested with R. robustus (742 insects collected). The distribution of palm species varied in each community, A.maripa was the only species found in the most recently settled community (Araipá). Significant decreases in bug density were observed in A.maripa, in the community most recently established (Araipá) and in the two most anthropogenic landcover classes.Infection of insects by T. cruzi and T. rangeli was examined using molecular methods (mini exon SL_IR and sno-RNA-C11). Respectively, 123 (16.57%) and 69 (9.3%) insects in 31 (23.3%) and 17 (13.32%) palms were identified as positive for T. cruzi and T. rangeli. A lack of infection was detected in Araipá but no differences were observed between the different land cover classes. The strains of Trypanosoma cruzi were identified using four distinct molecular markers (mini-exon SL-IR, GPI, HSP60 and D7-24α-rRNA) as belonging to the lineage TCI specifically TcId and 10 (8.13%) individuals showed a mixed infection TCI-TCII. Twenty host species divided into three classes were identified (mammals, birds, reptiles) were identified as food source from blood meal from the bug gut with cytochrome b primers, specific for vertebrates (25.74% of meals). Eighty-one percent of meals were conducted on mammals, potential hosts of T. cruzi, specially on Tamandua tetradactyla,identified as the main food source. This host was clearly identified as a reservoir for T.rangeli and also suggested for T. cruzi.Phylogenetic analysis performed using cytochrome b sequences, identified Rhodnius individuals in the Tapajos region within clade II, which represent an extension of the range previously described for this clade. The use of the cytochrome b marker also revealed a phylogenetic structure (haplogroups) not found using microsatellite markers. This result showed that the history of the genes (mitochondrial genome) does not match the history of individuals (microsatellites, 10 loci). Population genetics analysis conducted using both markers did not reveal genetic structure within the study area between the communities or the landcover classes. The study revealed significant gene flow, which was not restricted by the fragmentation of the environment. The invasive dynamics of Attalea palm trees provide a functional connectivity for insects to move between the different landcover classes and communities. Due to the abundance of palm trees and their high connectivity, the presence of vectors and infected hosts moving between the different communities and landcover classes, the environmental risk constituted by Attalea palm tree presence of Chagas disease in Tapajós region will presumably continue to increase
112

Effects of habitat degradation on the evolutionary dynamics of populations in a rainforest cycad (Gymnospermae)

Lopez-Gallego, Cristina 18 May 2007 (has links)
In addition to habitat loss and fragmentation, habitat degradation can have important consequences for biodiversity and population persistence, including effects on ecological and genetic processes beyond decreased demographic viability and the loss of genetic variation. Particularly interesting is the potential for evolutionary changes and adaptation to degraded habitats, that can affect population viability even in the short-term. Here, I explore how environmental changes after habitat degradation affect the evolutionary dynamics of populations of the rainforest cycad Zamia fairchildiana, specifically how habitat degradation affects gene dispersal, inbreeding, directional selection, and genotype-by-environment interactions, and the potential for genetic differentiation between populations. Colonies of Z. fairchildiana showed little genetic differentiation in neutral molecular markers across study sites, thus can be considered as subpopulations. Subpopulations in the disturbed habitat are experiencing different environmental conditions when compared to subpopulation in their native habitat. Disturbed-habitat subpopulations showed a faster life-history. This faster life history is associated with a weaker spatial genetic structure and higher levels of inbreeding in the disturbed-habitat subpopulations. In addition, higher light availability in the disturbed habitat seems to be a major agent of selection on traits like leaf production that have the potential to respond to selection in these subpopulations. Different traits were under selection in the native-habitat subpopulations, suggesting the potential for genetic differentiation between native and disturbed-habitat subpopulations. Genotype by environment interactions in seed germination and seedling survival, in response to light and water availability, further suggested that subpopulations can adaptively diverge between habitats, but the relative role of genetic and environmental factors, particularly maternal effects, on the magnitude and rate of genetic differentiation between subpopulations remains to be evaluated. These results suggest that habitat degradation can have important consequences for the evolutionary dynamics of populations of this cycad, not necessarily typical of habitat loss and fragmentation. This study identified factors and processes important for population persistence in degraded habitats, but population responses to habitat degradation are complex. Thus further studies and long-term experiments are required for better understanding the effects of habitat degradation on population viability.
113

Les populations invasives de rongeurs en milieu agricole : une étude menée dans des cultures de grande échelle, les plantations de palmiers à huile en Indonésie : Approche paysagère, génétique et écotoxicologique / Invasive populations of rodents in agricultural landscape : a study in crops at large-scale, the oil palm plantations in Indonesia : landscape, genetic and ecotoxicological approaches

Andru, Julie 21 December 2012 (has links)
Les perturbations environnementales d’origine anthropique favorisent l’établissement de populations invasives. La gestion de ces populations est primordiale pour la santé publique (zoonose, famine), l’environnent (perte de biodiversité), et l’économie (dégâts). L’objectif de cette thèse pluridisciplinaire, menée en conditions naturelles, est d’améliorer les connaissances sur les populations invasives de rongeurs dans des paysages agricoles à grande échelle et d’appréhender les mécanismes d’adaptation qui favorisent une réponse positive aux pressions anthropiques. Les résultats montrent que (1) le rat endémique Rattus tiomanicus, dont la présence est associée à la typologie de l’habitat naturel, et le rat introduit Rattus tanezumi-R3, dont la présence est associée aux activités humaines, constituent les populations invasives des plantations de palmier à huile en Indonésie; (2) leur distribution géographique clinale est probablement contemporaine à l’anthropisation des milieux, et suppose une compétition inter-spécifique; (3) ces grandes populations sont spatialement continues avec un flux génique limité par la distance géographique (caractérisées par un patron d’isolement par la distance) et potentiellement influencé par les transports routiers; (4) R. tanezumi-R3 possède une forte résistance physiologique aux raticides AVK, dont l’origine n’est pas associée à une mutation génétique de la molécule cible mais probablement liée aux enzymes du métabolisme. Ces travaux soulignent des stratégies d’adaptations comportementales et physiologiques des populations invasives de rongeurs en milieux agricoles et procurent des bases pour l’élaboration de stratégies de lutte adaptée / Anthropogenic activities modulate landscape and promote the establishment of invasive populations. Management of these populations represents a major issue for public health (zoonotic disease, famine), environment (biodiversity loss) and economy (damages). This multidisciplinary thesis has been conducted in natural conditions on populations of rodents infesting agricultural landscapes at large scale. This work aims to understand biological mechanisms that promote adaptations to anthropogenic pressures. The results suggest that (1) two species may infest oil palm plantations in Indonesia: an endemic rat Rattus tiomanicus - which presence is associated with natural habitat typology - and an introduced rats Rattus tanezumi-R3 - which occur in association with the Human Footprint- ; (2) clinal geographic distribution of these species is probably due to both phylogeography and contemporary human activities, and suggest interspecific competition; (3) genetic isolation by distance patterns among these populations, and restricted gene flow potentially influenced by road transport; (4) R. tanezumi-R3 developed a strong physiological resistance to coumatetralyl under AVK exposure. This resistance is not associated with a genetic mutation of the target molecule, and may relate to metabolic enzymes. This work highlights behavioral and physiological adaptations of invasive populations of rodents in agricultural landscape, and thus provides scientific basis for integrated pest management
114

Distribution, écologie et évolution de l'hyperaccumulation des éléments en traces par Noccaea caerulescens / Distribution, ecology and evolution of trace element hyperaccumulation by Noccaea caerulescens

Gonneau, Cédric 26 March 2014 (has links)
Noccaea caerulescens est la principale Brassicacée hyperaccumulatrice de Cd, Ni et Zn, candidate pour la phytoremédiation des sols contaminés. La distribution de l'espèce se caractérise par une importante hétérogénéité des facteurs environnementaux, et plus particulièrement en ce qui concerne la nature des sols. En outre, des variations importantes de la capacité d'hyperaccumulation entre les populations de l'espèce ont déjà été observées. Dès lors, à partir d'un vaste échantillonnage en France et ses régions limitrophes, l'objectif de cette thèse était de : i) mieux appréhender l'écologie de N. caerulescens notamment les composantes édaphiques de son habitat, iii) comparer les capacités d'accumulation en Cd, Ni et Zn et, iii) déterminer les relations génétiques entre les populations. Nos résultats montrent que N. caerulescens est largement répandue dans les massifs montagneux et que l'espèce n'est pas inféodée aux sites métallifères vu le nombre de stations en milieu non minier. Par ailleurs, les stations se caractérisent par une très large amplitude des paramètres édaphiques conduisant à proposer une nouvelle classification des stations. Concernant l'accumulation des éléments en traces in situ, nous avons démontré que la biodisponibilité ne permettait pas d'expliquer seule les concentrations observées dans la plante. Par ailleurs, des cultures en hydroponie ont mis en évidences un compromis entre l'allocation du carbone et l'accumulation des éléments en traces en particulier chez les populations sur serpentines. Enfin, l'analyse de la structure génétique neutre a fait ressortir trois zones géographiques fortement différenciées, sans cohérence avec le type de milieu / Noccaea caerulescens (Brassicaceae) is the main hyperaccumulator of Cd, Ni and Zn, candidate for phytoremediation of contaminated soils. The distribution of the species is characterized by a high degree of heterogeneity of environmental factors, especially concerning the soil composition. In addition, significant variations in the hyperaccumulation ability between populations of the species have been observed. Therefore, from a broad sampling in France and its neighboring regions, the aim of this thesis was: i) a better understanding of the ecology of N. caerulescens including soil habitat components, iii) a comparison of the ability of populations to accumulate Cd, Ni and Zn and iii) the assessment of the genetic structure among populations. Our results show that N. caerulescens is widespread in the French mountains and not restricted to the metalliferous sites given the large number of non-metalliferous stations explored. In addition, the prospected stations are characterized by a wide range in the soil composition leading to propose a new classification of N. caerulescens stations. On the accumulation of trace elements in situ, we have shown that the bioavailability of trace elements was not the only factor explaining the observed concentrations in the plant. Moreover, hydroponic cultures highlighted a compromise between carbon allocation and accumulation of trace elements especially in serpentine populations. Finally, the analysis of the neutral genetic structure highlighted three geographic regions highly differentiated, but not consistent with the edaphic type
115

Méthodes bayésiennes en génétique des populations : relations entre structure génétique des populations et environnement / Bayesian methods for population genetics : relationships between genetic population structure and environment.

Jay, Flora 14 November 2011 (has links)
Nous présentons une nouvelle méthode pour étudier les relations entre la structure génétique des populations et l'environnement. Cette méthode repose sur des modèles hiérarchiques bayésiens qui utilisent conjointement des données génétiques multi-locus et des données spatiales, environnementales et/ou culturelles. Elle permet d'estimer la structure génétique des populations, d'évaluer ses liens avec des covariables non génétiques, et de projeter la structure génétique des populations en fonction de ces covariables. Dans un premier temps, nous avons appliqué notre approche à des données de génétique humaine pour évaluer le rôle de la géographie et des langages dans la structure génétique des populations amérindiennes. Dans un deuxième temps, nous avons étudié la structure génétique des populations pour 20 espèces de plantes alpines et nous avons projeté les modifications intra spécifiques qui pourront être causées par le réchauffement climatique. / We introduce a new method to study the relationships between population genetic structure and environment. This method is based on Bayesian hierarchical models which use both multi-loci genetic data, and spatial, environmental, and/or cultural data. Our method provides the inference of population genetic structure, the evaluation of the relationships between the structure and non-genetic covariates, and the prediction of population genetic structure based on these covariates. We present two applications of our Bayesian method. First, we used human genetic data to evaluate the role of geography and languages in shaping Native American population structure. Second, we studied the population genetic structure of 20 Alpine plant species and we forecasted intra-specific changes in response to global warming. STAR
116

Variabilidade genética e química entre e dentro de populações de Casearia sylvestris Sw. (Salicaceae) no estado de São Paulo /

Cavallari, Marcelo Mattos. January 2008 (has links)
Resumo: O presente trabalho teve como objetivo produzir ferramentas e informações úteis para a conservação e exploração racional de Casearia sylvestris Sw. (Salicaceae), uma espécie que produz diterpenos clerodânicos de grande importância farmacológica (casearinas), e que é explorada por extrativismo. Tal objetivo foi alcançado através do desenvolvimento de marcadores microssatélites específicos para C. sylvestris e de um estudo da diversidade genética e química existente entre e dentro de populações do Estado de São Paulo. Tradicionalmente são reconhecidas duas variedades em C. sylvestris (var. sylvestris e var. lingua), o que é motivo de debate devido à existência de formas intermediárias. Este trabalho objetivou, adicionalmente, contribuir com argumentos genéticos para esta discussão. Foi construída uma biblioteca enriquecida em microssatélites, a partir da qual obtiveram-se e validaram-se dez pares de iniciadores (primers) microssatélites específicos para C. sylvestris. Estes pares de iniciadores foram utilizados para o estudo da estrutura genética de populações de C. sylvestris através da amostragem de 376 indivíduos em nove populações distribuídas em quatro ecossistemas (Floresta Ombrófila Densa, Floresta Estacional Semidecidual, Cerrado e ecótonos). As duas variedades foram amostradas de acordo com sua distribuição nestes ecossistemas. A genotipagem dos indivíduos para os locos amostrados foi realizada através de eletroforese em gel de acrilamida lido a 700 e 800 nm por um seqüenciador IR2-DNA Analyser (LI-COR). Os dados foram analisados através de abordagens frequentistas, bayesianas e baseadas na teoria de coalescência, utilizando-se diversos programas computacionais. Para o estudo da diversidade química, as mesmas populações foram amostradas, selecionando-se 12 indivíduos por população, totalizando 108 indivíduos. Adicionalmente, foram... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work aimed obtaining tools and information for the conservation and rational exploitation of Casearia sylvestris Sw. (Salicaceae), a tree species which produces casearins, pharmacologically important clerodane diterpenes. This goal was achieved through the development of a set of polymorphic microsatellite markers, and through the study of chemical and genetic diversity in populations of C. sylvestris from São Paulo State. Also, we aimed contributing for the debate on the existence of two varieties within this species (var. sylvestris e var. lingua). A genomic library was constructed and 10 primer pairs were obtained. Those primers were utilized for a population genetic structure analysis, in which 376 individuals from nine populations distributed on four different ecosystems (Evergreen Atlantic Forest, Semideciduous Atlantic Forest, Cerrado and ecotones) were sampled. The two varieties were sampled according to its distribution among these populations. Genotyping was performed at 700 and 800 nm by electrophoresis on an IR2-DNA Analyser (LI-COR). The data were analyzed through frequentist, Bayesian and coalescence-based approaches, through the use of several softwares. Chemical diversity was studied by sampling in the same populations (12 individuals per population, i.e. 108 individuals). Also, cuttings of these individuals were prepared, aiming to verify its' chemical compounds after a year of green-house cultivation. Cuttings' rooting was problematic and a methodology was developed. Only 46 cuttings survived. Casearins from these 154 individuals (108 + 46) were extracted and analyzed by HPLC. Genetic analysis results suggests a partial genome duplication, as more than two alleles for the same locus were observed in 8% of var. sylvestris individuals and in 70% of var. lingua individuals. Additional studies are necessary to verify the hypothesis of partial genome duplication... (Complete abstract click electronic access below) / Orientador: Marcos Aparecido Gimenes / Coorientador: Alberto José Cavalheiro / Banca: Roseli B. Torres / Banca: Maria Imaculada Zucchi / Banca: Giancarlo C. X. Oliveira / Doutor
117

Análises das variações fitoquímicas, estruturas genética e importância econômica de Annona crassiflora Mart., no cerrado / Analysis of phytochemical variation, genetic structure and economic importance of Annona crassiflora Mart., in cerrado

Egydio, Anary Priscila Monteiro 30 April 2009 (has links)
A Annona crassiflora Mart. é uma espécie frutífera nativa do cerrado que possui alto potencial de uso e ampla distribuição. O presente trabalho tem os seguintes objetivos: identificar e quantificar aminoácidos livres, carboidratos solúveis e ácidos graxos da polpa e das sementes, visando ampliar os conhecimentos sobre potencial econômico de A. crassiflora; avaliar qual o nível de variações quantitativas e qualitativas de alcalóides de A. crassiflora de amostras provenientes de diferentes regiões do cerrado; avaliar qual a magnitude da diversidade genética entre diferentes populações de A. crassiflora, utilizando marcadores isoenzimáticos. Com relação às propriedades nutricionais, as análises de aminoácidos livres, carboidratos e lipídeos foram feitas por CLAE/F, por CLAE/CTI - DPA e por CG/EM, respectivamente. O teor total de aminoácidos livres na polpa variou de 1101,99 g/g a 1975,7 g/g de massa seca, enquanto nas sementes variou de 636,3 μg/g a 17.445,83 μg/g de massa seca. A glutamina foi majoritária em todas as amostras. O teor total dos carboidratos solúveis da polpa variou de 11,5 g/100g a 17,03 g/100g e das sementes variou de 13,69 g/100g a 40,47 g/100g de matéria seca. Foram detectadas a frutose, a glicose e a sacarose em todas as amostras de polpa e de sementes. A quantidade de lipídeos totais da polpa variou de 7g/100g a 16,2 g/100g de massa seca e das sementes variou de 34,36 g/100g a 35,98 g/100g de massa seca. O ácido oléico e/ou petroselínico (18:1) foram majoritários em todas as amostras de polpa e de sementes de diferentes origens geográficas. Certamente os dados obtidos permitiram ampliar os conhecimentos sobre potencial de aproveitamento dessa espécie. Para avaliar a magnitude da variação dos alcalóides das folhas de A. crassiflora, a quantificação e identificação dos alcalóides foram feitas, respectivamente, por CG/FID e CG/EM. Foi verificado que o teor total de alcalóides variou de 221,1 ± 17,14 μg/g a 2986,89 ± 367,1 μg/g de massa seca. Foram identificados os alcalóides anonaína, anoretina, romucosina e xilopina que mostraram diferenças entre as regiões. Essa variação na concentração e no perfil alcaloídico das populações de A. crassiflora sugere ampla plasticidade fenotípica desses metabólitos em resposta a fatores bióticos e/ou abióticos, além de alta variabilidade genética relacionada à expressão dos genes envolvidos na biossíntese desses metabólitos. A avaliação da estrutura genética foi feita através da análise isoenzimática. Os dados isoenzimáticos mostraram baixa variabilidade genética. Duas hipóteses são apontadas para explicar o baixo nível de polimorfismos verificado em A. crassiflora, uma delas relacionada à técnica e outra relacionada ao próprio processo de degradação do ambiente. Diante do exposto, os dados obtidos no presente trabalho sugerem formas de agregar mais valor econômico e ecológico à A. crassiflora e podem proporcionar uma base para o uso mais eficiente e racional dos recursos dessa espécie, contribuindo para exploração sustentável do cerrado, o que permite também o desenvolvimento de comunidades locais. / Annona crassiflora Mart. is a native fruit tree species from the cerrado, possessing high use potential and a wide distribution. The proposed aims were to identify and quantify free amino acids, free sugars and fatty acids in the pulp and seeds of this plant, with a view to widening knowledge on economical potentiality, as well as to evaluate the level of alkaloid quantitative and qualitative variation in samples coming from different regions of the cerrado, and finally define the size of genetic diversity among these different populations by using isoenzymatic markers. As to nutritional properties, analyses of free amino acids, free sugars and fatty acids were undertaken with, respectively, CLAE/F, CLAE/CTI DPA and CG/MS. The total rate of free amino acids in the pulp varied from 1101,99 ug/g to 1975,7 ug/g of dry mass, whereas in the seeds this variation was from 636,3 μg/g to 17.445,83 μg/g. Glutamin was preponderant in all the samples. Total free sugar rate in pulp varied from 11,5 g/100g to 17,03 g/100g and in seeds from 13,69 g/100g to 40,47 g/100g of dry matter. Fructose, glucose and sacarose was detected in all samples. The amount of total lipids in pulp varied from 7 g/100g to 16,2 g/100g of dry weight and in seeds from 34,36 g/100g to 35,98 g/100g. Oleic and/or petroselinic acids (18:1) were the most abundant in all pulp and seed samples from the different geographic regions. The obtained results certainly permit widening knowledge on the potentiality for use of this plant species. In order to evaluate the size of alkaloid variation in A. crassiflora leaves, alkaloid quantification and identification was done with, respectively, CG/FID and and CG/EIMS. It was noted that the total alkaloid rate varied from 221,1 ± 17,14 ug/g to 2986,89 ± 367,1 μg/g of dry mass. The alkaloids anonain, anoretin, romucosin and xilopin were identified, these showing differences among regions. This variation in alkaloid concentration and profile in A. crassiflora populations suggests the wide phenotypic plasticity of these metabolites in response to biotic and/or abiotic factors, besides high genetic variability related to gene expression of those involved in their biosythesis. Genetic structure evaluation was done through isoenzymatic analysis. Isoenzymatic data revealed low genetic variability. Two hypotheses may be raised to explain this low polymorphism level. The first points to inefficient isoenzymatic techniques in reckoning species genetic diversity, whereas the second takes into consideration that excessive homozygosis (indicated by the low level of isoenzymatic variability) could be an indication of the process of species genetic erosion, possibly related to habitat (cerrado) degradation. In view of this, data obtained in the present study suggest forms of aggregating additional economical and ecological value to A. crassiflora, and could furnish a base for the more efficient and rational use of resources from this species, thus contributing to sustainable exploitation of the cerrado, and also allowing for local community development.
118

Variabilidade genética em populações de Heliothis virescens (Lepidoptera: Noctuidae) no Brasil inferida por marcadores microssatélites / Heliothis virescens (Lepidoptera: Noctuidae) populational genetic variation in Brazil inferred by microsatellite markers

Domingues, Felipe Antonio 16 June 2011 (has links)
Estudos de genética de populações de pragas agrícolas têm destacado a importância de se conhecer a estruturação genética e os padrões de fluxo gênico entre populações para o refinamento de estratégias de Manejo Integrado de Pragas (MIP). A lagarta-da-maçã do algodoeiro, Heliothis virescens (F.), é um inseto praga amplamente distribuído e importante economicamente por causar danos consideráveis à cultura do algodão no Brasil. O controle dessa praga tem sido feito principalmente pelo uso de inseticidas e de plantas geneticamente modificadas (GM) que expressam proteína(s) de Bacillus thuringiensis Berliner e o potencial de evolução da resistência é alto. O conhecimento de quanto as populações de H. virescens são capazes de trocar informação genética entre si é de fundamental importância para a implantação de estratégias de manejo dessa praga. No entanto, pouco se sabe sobre a estrutura genética e os padrões de fluxo gênico em H. virescens em escalas locais e regionais no Brasil. Assim, o objetivo desse trabalho foi avaliar a variabilidade genética em populações de H. virescens utilizando marcadores microssatélites. Foram amostrados indivíduos de H. virescens oriundos de populações coletadas nas safras de 2007/08, 2008/09 e 2009/10 nas principais regiões produtoras de algodão e soja no Brasil. Foram estudados nove locos polimórficos em 12 populações, em um total de 205 indivíduos. O número médio de alelos por loco foi de 14,11. Os valores de heterozigosidade média esperada (HE) e observada (HO) foram de 0,303 e 0,438, respectivamente. O coeficinete de endocruzamento da espécie f foi de 0,294 (IC 95% de 0,178 a 0,406). As estimativas de estruturação genética foram = 0,132 (IC 95% de 0,072 a 0,218) e RST = 0,252. Esses valores indicam uma estruturação genética moderada entre as populações. Estimativas do número de migrantes indicaram um pequeno fluxo gênico, principalmente no sentido Centro- Oeste Nordeste, embora a maioria dos indivíduos dentro das populações seja residente; adicionalmente, foi verificado que o estabelecimento das populações do algodão ocorre a partir de indivíduos migrantes da soja ou descendentes desses indivíduos. Análises de Componentes Principais e de atribuição usando inferência Bayesiana revelaram a formação de dois grupos, porém não foi possível identificar um padrão de agrupamento (por região, safra ou hospedeiro). Desta forma os resultados do presente trabalho sugerem uma estruturação genética incipiente para as populações de H. virescens no Brasil. Desse modo, é importante levar esses resultados em consideração para que o MIP em geral, e especificamente para que as abordagens para retardar a evolução da resistência sejam implementadas de forma efetiva para o manejo de H. virescens no Brasil. / Agricultural pests population genetics studies have emphasized the importance of genetic structure and patterns of gene flow knowledge for Integrated Pest Management (IPM) strategies. The tobacco budworm, Heliothis virescens (F.), is a widespread and economically important insect pest renowned for causing considerable damage in cotton fields in Brazil. This pest has been controlled by the use of insecticides and genetic modified plants (GM) expressing proteins from Bacillus thuringiensis Berliner, and it has already been shown to present a high potential to develop resistance to these control technologies. To a successful application of these strategies it is needed to know the capacity of the pest populations to exchange genetic information among them. However, for H. virescens a scarce amount of information about genetic structure and patterns of gene flow is available at local and regional scales in Brazil. In this way, the main objective of this study was to evaluate the genetic variability of H. virescens based on microsatellite markers. Specimens were sampled during 2007/08, 2008/09 and 2009/10 from the main cotton and soybean producers regions in Brazil. From this, nine polymorphic loci from 12 populations were studied in 205 specimens. The average number of alleles was 14.11. Expected (HE) and observed (HO) heterozygosity were 0.303 and 0.438, respectively. Inbreeding coefficient f was 0.294 (IC 95% 0.178 - 0.406). Genetic structure indices were: = 0.132 (IC 95% 0.072 0.218) and RST = 0.252. These values point to a moderate genetic structure among H. virescens populations. Migrants estimative indicate a low gene flow, mainly in the Center-Western Northern direction, although most individuals are residents within populations; additionally it was suggested that immigrants to cotton populations come from soybean fields. Genetic relationships inferred by Principal Component Analysis and Bayesian assignment tests identified two groups, although no group pattern was recognized, even by geographic region, year of sampling or host plant. These results suggest an incipient genetic structuring for H. virescens populations within Brazil. Thus, such results should be considered for IPM strategies aiming in an efficient control of H. virescens in Brazil.
119

Diversidade e estrutura genética de populações de batata da serra (Ipomoea serrana Sim.-Bianch. & L.V. Vasconcelos) da Chapada Diamantina, Bahia, utilizando marcadores ISSR / Genetic diversity and structure of batata-da-serra populations (Ipomoea serrana Sim.-Bianch. & L.V. Vasconcelos) from Chapada Diamantina, Bahia, using ISSR markers

Gonçalves, Tatiane de Oliveira 06 April 2016 (has links)
A batata-da-serra, Ipomoea serrana Sim.-Bianch. & L.V. Vasconcelos, é uma liana endêmica da Chapada Diamantina, Bahia, cuja raiz tuberosa e consumida por populações humanas ha muitos anos. Apesar da espécie, classificada como vulnerável pela IUCN (União Internacional para a Conservação da Natureza), estar submetida à pressão antrópica devido à exploração de raízes tuberosas, para uso na alimentação, são raros os estudos com a espécie, razão pela qual e de grande importância conhecer a diversidade e estrutura genética da espécie. Estudos sobre diversidade e estrutura genética a partir de marcadores moleculares são importantes por fornecerem dados sobre impactos da exploração antrópica sobre as populações, podendo oferecer subsídio para planos de manejo e conservação de espécie. Cinco populações da Chapada Diamantina, constituindo um total de 142 indivíduos, foram investigados com quatro iniciadores Inter Simple Sequence Repeats (ISSR), resultando em 34 bandas, das quais 25 foram polimórficas. A analise dos parâmetros genéticos mostrou que as populações apresentam variabilidade moderada, com 73,8% de bandas polimórficas, 0,264 de índice de diversidade de Nei e 0,389 de índice de Shannon (valores médios). A maior parte da variação ocorreu dentro das populações (77%), estimado pela analise de variância molecular (AMOVA), enquanto que a variação entre populações foi de 23%, o que corroborou os resultados de estruturação obtidos pelo programa Structure, analise de coordenadas principais (PCoA) e agrupamento estimado pelo método Neighbor-Joining, a partir do coeficiente de dissimilaridade de Jaccard. A analise Bayesiana separou os indivíduos em quatro grupos, sendo que as populações Andaraí e Capão foram alocadas em grupos distintos, enquanto as outras três populações compartilharam indivíduos distribuídos em outros dois grupos. Este estudo, por seu caráter pioneiro com relação aos marcadores moleculares, constituiu o primeiro passo para o conhecimento da diversidade genética da espécie. Estudos futuros poderão ampliar o conhecimento sobre a espécie podendo oferecer subsidio para a elaboração de um plano de manejo para esta espécie que tem sido explorada na região. / batata-da-serra, Ipomoea serrana Sim.-Bianchi. & L.V. Vasconcelos, is an endemic liana from the Chapada Diamantina, Bahia, whose tuberous roots have been consumed by human populations for many years. Although the species, classified as vulnerable by the IUCN (International Union for Conservation of Nature), is subject to anthropic pressure due to the exploration of tuberous roots for food consumption, few studies have been conducted on the species, which is why it is of great importance to know the diversity and genetic structure of the species. Studies on genetic diversity and structure with molecular markers are important for providing data on the impacts of anthropogenic exploitation and can be useful for the species management and conservation. Five populations of Chapada Diamantina, consisting a total of 142 individuals were studied with four ISSR primers, resulting in 34 bands, 25 of which were polymorphic. The genetic diversity analysis showed that populations have a moderate variability, with 73.8% of polymorphic bands, Nei\'s unbiased gene diversity (He) was 0.264; Shannon diversity index (I) was 0.389, average values. Most of the variation was within populations (77%), as estimated by the analysis of molecular variance (AMOVA), whereas the variation between populations was 23% of the total, which corroborated the results of program Structure, principal co-ordinate analysis (PcoA) and cluster analyses, using the Neighbor-Joining method, and the dissimilarity coefficient of Jaccard. The Bayesian analysis separated the individuals into four groups, with populations Andarai and Capao allocated into different groups, while the other three populations shared individuals in two other groups. Considering the pioneering characteristic of this study at the molecular level, it represents the first step towards the knowledge on the genetic diversity of the species. Future studies will increase the knowledge on the genetics of the species and may provide subsidy for the development of a management plan for a species that has been explored in the region.
120

Diversidade, estrutura genética e domesticação de piquiazeiros (Caryocar villosum) em duas localidades da Amazônia brasileira / Diversity, genetic structure and domestication of piquiás (Caryocar villosum) in two localities of the Brazilian Amazon

Francisconi, Ana Flávia 12 December 2018 (has links)
O piquiazeiro (Caryocar villosum (Aubl.) Pers.) é uma arbórea presente no bioma Amazônico, sendo seus principais usos os alimentícios e madeireiros. O piquiazeiro encontra-se incipientemente domesticado, e a seleção e manejo feitos por populações tradicionais pode estar promovendo a continuidade desse processo, que se iniciou na Amazônia por volta do final do Pleistoceno e inicio do Holoceno, e hoje está sendo retomado por populações tradicionais que fazem cultivos em seus quintais, entre elas o piquiazeiro. Apesar de seu uso por populações tradicionais e do potencial comercial, a diversidade e distribuição do piquiazeiro ainda foram pouco estudadas. Os objetivos desse estudo foram analisar a diversidade genética e a estrutura genética de piquiazeiros em duas situações. A primeira foi examinando o processo de domesticação do C. villosum por populações tradicionais na Floresta Nacional (FLONA) do Tapajós e a segunda foi comparando a população da FLONA do Tapajós, no Pará, com outra localizada na Reserva Extrativista (RESEX) Rio Ouro Preto, em Rondônia. Na FLONA foram genotipados, com o uso de sete marcadores microssátelites, 67 indivíduos da mata e 26 cultivados nos quintais. Maior riqueza alélica, número de alelos, número de alelos efetivos, alelos privados e heterozigosidade observada foram encontrados na mata, assim como estruturação genética espacial nos indivíduos de quintal, o que indica a domesticação da espécie, apesar da baixa estruturação genética encontrada entre os grupos mata/quintal nos métodos aplicados. Na segunda parte foram genotipados 130 piquiazeiros, sendo 92 do Pará, os mesmos utilizados no estudo da domesticação, somados a 38 de Rondônia. O Pará apresentou valores superiores para número médio de alelos/loco, número efetivo de alelos, número de alelos privados, riqueza alélica e heterozigosidade esperada, indicando um possível centro de origem da espécie. A estrutura genética espacial foi significativa em ambas as localidades, o que sugere correlações de parentesco entre os indivíduos, provavelmente devido ao comportamento forrageiro de seus polinizadores e dispersores. A estruturação genética entre as duas localidades foi observada em todos os métodos, sendo que a maior parte da variação (89%) ocorre dentro das populações. A diferenciação entre as populações (11%) pode ser explicada por fatores históricos e pelo elevado fluxo gênico (Nm = 2,043). Foi também feita uma modelagem de nicho ecológico para determinar a distribuição da espécie. Foi observada a predominância de ocorrência da espécie no bioma Amazônico, com maior adaptação a climas quentes, com médias superiores a 18°C em todos os meses, e úmido, apresentando de 1 a 3 meses de seca. / Piquiá (Caryocar villosum (Aubl.) Pers.) is a tree species present in the Amazon biome, used mainly for food and timber. Piquiá is incipiently domesticated, and the selection and management by traditional populations may be promoting the continuity of this process. This process began in the Amazon around the end of the Pleistocene and the beginning of the Holocene, and today is being resumed by traditional populations, which cultivate different species in their backyards, among them is the piquiá. Despite its constant use by traditional populations and commercial potential, the diversity and distribution of piquiá have been little studied. The objectives of this study were to analyze the genetic diversity and the genetic structure of piquiás in two different cases. The first was to examine the process of domestication of C. villosum by traditional populations in the Floresta Nacional (FLONA) do Tapajós. The second one was to compare the piquiás populations from the FLONA do Tapajós, in Pará, with another one located in the Reserva Extrativista (RESEX) Rio Ouro Preto, in Rondônia. Sixtyseven individuals from the forest and 26 cultivated in the backyards were genotyped, with the use of seven microsatellite markers, in FLONA. Higher allelic richness, number of alleles, number of effective alleles, private alleles and observed heterozygosity were found in the forest, as well as spatial genetic structuring in backyard individuals, which indicates the domestication of the species, despite the low genetic structure found between the forest/backyards groups in the applied methods. In the second part, 130 piquiás were genotyped, being 92 of Pará, the same ones used in the study of domestication, and 38 of Rondônia. Pará presented higher values for average number of alleles/locus, effective number of alleles, number of private alleles, allelic richness and expected heterozygosity, indicating a possible center of origin of the species. The spatial genetic structure was significant in both localities, suggesting kinship correlations among the individuals, probably due to the forage behavior of their pollinators and dispersers. Genetic structuring between the two localities was observed in all methods, with most of the variation (89%) occurring within populations, according to AMOVA. The differentiation between populations (11%) can be explained by historical factors and high gene flow (Nm = 2,043). According to the Ecological Niche Modeling, used to verify the species distribution, the piquiá occurs predominantly in the Amazonian biome, with best suitability in hot climates, with temperature averages above 18°C, and humid, presenting between 1 and 3 months of drought.

Page generated in 0.0518 seconds