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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.
731

Hybridization of the Self, Colonial Discourse and the Deconstruction of Value Systems : A Postcolonial Literary Theory Perspective of Literature inculpating Colonialism

Burns, Brian January 2021 (has links)
The aim of this essay is to provide a perspective on literature inculpating colonialism using postcolonial literary theory and method. The subject material incorporates four novels studied during the literature modules for the English course at Högskolan Gävle (HIG). The four novels combine to highlight various issues that affect the Self-identity through hybridization and colonial discourse as well as the detrimental nature of the colonial project for indigenous value systems during the period of colonialism. There is also application of theories and concepts raised in academic literature from within and outside the curriculum of HIG. The use of the postcolonial literary methodology provides a critical perspective of the aforementioned literature while implementing theories associated with that movement such as hybridity and the redefining of borders as well as focusing on the social, cultural, political and religious impact of the coloniser’s activities in the colonies as raised in the novels.  The most significant findings of this essay include the roles of isolation and disconnection within the colonial project and the subsequential effects on the colonised and their descendants. There are findings and observations of the level of strategic application of universalistic colonial discourse and the intrinsic application of the language used in the objectification of the indigenous and the subjugation of their value systems. The role of perception is also highlighted including findings on the social implications for the colonies inhabitants, both dissident and conformist, raised within the chosen literature and this essay. The essay also examines the application of various strands of literary theory incorporated within postcolonialism including poststructuralism and psychoanalytic criticism as well as anthropology material.  The conclusion of this essay culminates with the conflicting interpretations of progress as a universalism that counters the theories of postcolonialists and poststructuralists and their subsequent refusal to succumb to literature’s prevalence. The subjectivity of the postcolonial literary theorist and the self-imposed parameters restrict the interpretation of the colonial and postcolonial literature. The aforementioned progress defined by improved standards of health, education and social justice is lacking in presence in both the postcolonial literature and the accompanying literary theory counterpart. Subsequently, the disconnected voice of isolation and the split/double identity take precedence over higher standards of living and the appreciation of access to improved human rights and social justice within postcolonial society.
732

Social hybridogenesis in ants of the genus Cataglyphis

Darras, Hugo 26 June 2017 (has links) (PDF)
Les Hyménoptères sociaux (abeilles, fourmis et guêpes) doivent leur succès écologique à une division dutravail marquée par l’existence de castes. Les reines sont spécialisées dans la reproduction, tandis que les ouvrières sont stériles et prennent en charge la construction du nid et sa défense, la récolte de nourriture et l’élevage des jeunes. Le développement d’un œuf femelle en une reine ou une ouvrière est généralement régi par des facteurs environnementaux, tels que la qualité ou la quantité de la nourriture.En réalisant une étude de génétique des populations chez la fourmi Cataglyphis hispanica, nous avons mis en évidence un mode de reproduction inhabituel appelé hybridogenèse sociale. Cette espèce est caractérisée par la co-existence de deux lignées génétiques au sein des populations. Les reines de chaque lignée s’accouplent systématiquement avec un mâle de l’autre lignée génétique. Ainsi, les reines de la lignée 1 s’accouplent toujours avec un mâle de la lignée 2, et les reines de la lignée 2 s’accouplent avec un mâle de la lignée 1. Les ouvrières sont issues du croisement entre les deux lignées :il s’agit donc d’individus hybrides. A l’inverse, les individus reproducteurs (nouvelles reines et mâles) sont produits exclusivement par reproduction asexuée. La caste femelle (reine ou ouvrière) est donc déterminée génétiquement; les ouvrières portent un génome hybride, alors que les reproducteurs possèdent un génome non-hybride hérité exclusivement de la mère.Les travaux réalisés dans le cadre de cette thèse de doctorat visent à comprendre l’origine et l’évolution de l’hybridogenèse sociale chez les fourmis Cataglyphis par le biais d’approches variées (génétique des populations, phylogéographie et manipulation de colonies en laboratoire). Ils sont articulés selon plusieurs axes complémentaires :la description du phénomène, l’étude de sa distribution géographique et phylogénétique au sein du genre Cataglyphis, et l'étude de ces mécanismes génétiques sous-jacents. / In eusocial Hymenoptera, such as bees, wasp and ants, it is commonly accepted that the diploid female eggs are bipotent and develop either into a queen or a worker depending on environmental factors. While conducting a population genetic study of the ant Cataglyphis hispanica, we discovered an unusual reproductive system called social hybridogenesis. Under this system, queens and workers develop from eggs with different genetic make-up. Two divergent genetic lineages coexist within a population. Queens of each lineage mate with males originating from the other lineage. Workers are produced by sexual reproduction; hence, they are first generation hybrids of the two lineages. By contrast, new queens and males are produced by thelytokous and arrhenotokous parthenogenesis, respectively. By using alternative modes of reproduction, queens appear to maximize their reproductive success by increasing the transmission rate of their genes to the reproductive offspring while benefiting from genetic diversity and heterosis effects in their worker force. Males, however, do not contribute genes to the next generation as they only sire sterile workers. This system is expected to be evolutionary short-lived as lineages may be selected to stop the production of males with null direct fitness. This PhD project aims at understanding the origin and evolution of social hybridogenesis in Cataglyphis. Using several different approaches including population genetics methods based on microsatellite makers, phylogeography and experimental manipulations on lab colonies, I explored tthe characteristics of social hybridogenesis, the genetic mechanisms underlying the system and its distribution within the genus Cataglyphis. My results, together with other recent findings, question the paradigm of environmental caste determination in eusocial Hymenoptera and suggest that genetic influences on caste determination may be more common than previously thought. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
733

Thermodynamics of RNA-RNA binding

Mückstein, Ulrike, Tafer, Hakim, Hackermüller, Jörg, Bernhart, Stephan H., Stadler, Peter F., Hofacker, Ivo L. 24 October 2018 (has links)
Background: Reliable prediction of RNA–RNA binding energies is crucial, e.g. for the understanding on RNAi, microRNA–mRNA binding and antisense interactions. The thermodynamics of such RNA–RNA interactions can be understood as the sum of two energy contributions: (1) the energy necessary to ‘open’ the binding site and (2) the energy gained from hybridization. Methods: We present an extension of the standard partition function approach to RNA secondary structures that computes the probabilities Pu[i, j] that a sequence interval [i, j] is unpaired. Results: Comparison with experimental data shows that Pu[i, j] can be applied as a significant determinant of local target site accessibility for RNA interference (RNAi). Furthermore, these quantities can be used to rigorously determine binding free energies of short oligomers to large mRNA targets. The resource consumption is comparable with a single partition function computation for the large target molecule. We can show that RNAi efficiency correlates well with the binding energies of siRNAs to their respective mRNA target.
734

Evolution of the genus Aristolochia (Aristolochiaceae) in the Eastern Mediterranean including the Near East and Caucasia

Mahfoud, Hafez M. 09 February 2010 (has links)
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.
735

Investigating the localization mechanism of Bsg25D mRNA in Drosophila melanogaster

Velupillai, Sinduja 04 1900 (has links)
Le transport subcellulaire et la traduction localisée des molécules d'ARNm semble être un processus très répandu et important pour contrôler la distribution asymétrique des protéines dans les cellules. L’ARNm, Bsg25D, connu pour se localiser aux centrosomes et aux microtubules astraux dans les embryons de drosophile au cours des premiers événements d'embryogenèse, a été sélectionné pour déterminer le rôle et l'importance du ciblage de l'ARNm à l'appareil mitotique lors de la division cellulaire. La localisation de Bsg25D aux centrosomes dans les embryons de drosophile est conservée entre espèces telles que D. melanogaster, D. simulans et D. yakuba. Bsg25D encode une protéine qui est étroitement liée à la Ninein (Nin) et à la Ninein-like protein (Nlp), deux protéines associées aux centrosomes présentes dans les cellules mammifères. L’analyse structure-fonction démontre que la région codante et la région 3’UTR de Bsg25D sont nécessaires pour son ciblage. Ceci suggère qu’un élément de régulation en cis, qui favorise sa localisation se situe dans la région codante + 3’UTR. / The subcellular transport and localized translation of mRNA molecules is emerging as a highly prevalent and important process for controlling asymmetric protein distribution in cells. A candidate mRNA, Bsg25D, known to localize to centrosomes and astral microtubules in Drosophila embryos during early events of embryogenesis, was selected to determine the role and importance of mRNA targeting to the mitotic apparatus during cell division. The localization of Bsg25D to centrosomes in Drosophila embryos is conserved between species such as D. melanogaster, D. simulans and D. yakuba. Bsg25D encodes a protein closely related to centrosome-associated proteins Ninein (Nin) and Ninein-like protein (Nlp) in mammalian cells. Structure function analysis revealed that the coding and 3’UTR of Bsg25D are necessary for its targeting pattern, suggesting that a cis-regulatory motif that drives its localization, is in the coding + 3’ UTR region.
736

α<sub>2</sub>-Adrenergic Receptors in Human Spinal Cord: Specific Localized Expression of mRNA Encoding α<sub>2</sub>-Adrenergic Receptor Subtypes at Four Distinct Levels

Smith, Mark Stafford, Schambra, Uta B., Wilson, Katrina H., Page, Stella O., Hulette, Christine, Light, Alan R., Schwinn, Debra A. 01 December 1995 (has links)
α2-Adrenergic receptor (AR) subtype mRNA (α2a, α2b, α2c) neuronal localization in human spinal cord has not been described. We therefore performed in situ hybridization to identify cell bodies at four levels of human spinal cord (cervical, thoracic, lumbar, sacral) containing α2AR subtype specific mRNA. α2AR mRNA is present in gray matter only (ventral > dorsal; sacral > cervical > thoracic = lumbar). In addition to α2AR mRNA in cell bodies in thoracic and lumbar intermediolateral (sympathetic) and sacral intermediate (parasympathetic) cell columns (lamina VII), all levels in dorsal horn laminae I, II, V, and ventral horn lamina IX, we demonstrate α2AR mRNA in dorsal horn laminae III and IV, and dorsal nucleus of Clarke, where α2ARs have not been described. Previously unreported heterogeneity in α2AR subtype distribution (α2a and α2bAR mRNA present, α2cAR mRNA virtually absent) is found at all sites of α2AR mRNA expression in human spinal cord, including locations known to mediate effects of α2AR agonist drugs on nociception, autonomic function and motor tone. Cervical spinal cord demonstrates a predominance of α2a mRNA signal, while thoracic, lumbar, and sacral spinal cord demonstrate an increasing predominance of α2bAR mRNA. If confirmed at a protein level, these findings have profound implications for therapeutic strategies in managing human pain.
737

Stratégies et Management de l'Innovation de Rupture dans les Pays Emergents : le cas du Véhicule Electrique en Chine / Strategies and Management of Disruptive Innovation in Emerging Countries : the case of Electric Vehicles in China

Chen, Bo 26 January 2018 (has links)
Le marché du véhicule électrique (VE) en Chine est en pleine effervescence, mais les constructeurs occidentaux peinent à y déployer leurs produits. Pourtant, les crédits d’émissions carbone générés par les ventes de VE sont nécessaires à la survie de leur business de véhicules thermiques dans ce marché. Dès lors, quelles sont les pistes stratégiques à fort potentiel pour les constructeurs étrangers ?En collaboration avec Renault et basée sur cinq missions en Chine entre 2012 et 2016, cette thèse CIFRE dresse d’abord un état de l’art de l’opaque marché du VE en Chine, à la fois généré top-down par des initiatives gouvernementales et bottom-up par des VE low-cost et illégaux, les Micro VE. Nous réalisons une typologie des modèles, des usages, des prix et des territoires de déploiement. Alors que le marché subventionné – hors haut de gamme – ne parvient pas à séduire les consommateurs, c’est en bas du marché officiel et chez les Micro VE illégaux qu’un marché naturel se développe, avec plus d’un million de Micro VE vendus sans aides à l’achat à des particuliers depuis 2009.Dans ce contexte institutionnel spécifique et face à cette double incertitude produit et marché, en appui sur les théories de conception innovante, nous développons un cadre théorique d’exploration stratégique basé sur la combinaison systématique de variables stratégiques et leur évaluation. Nous identifions ainsi deux pistes innovantes et non encore engagées par les constructeurs étrangers : « l’autopartage électrique » et le « VE low-cost ».Sur le volet « autopartage électrique », nous comparons Autolib’ (Paris) et United Journey (Shenzhen), deux systèmes en libre-service basés sur des stations qui semblent pointer vers la mobilité du futur et attirent l’attention des autorités chinoises. Toutefois, en plus de la fragilité des modèles d’affaires, cette piste semble difficile à poursuivre pour les acteurs étrangers dû aux protectionnismes locaux et à la complexité des partenariats publics-privés en Chine, souvent basés sur des réseaux d’institutions informelles.Sur le volet « VE low cost », nous approfondissons les connaissances sur le marché illégal des Micro VE. Une enquête de terrain approfondie dans la province du Shandong permet de caractériser le marché ainsi que les scenarios réglementaires de sa légalisation. Ce marché répond à des besoins véritables de mobilité dans les villes chinoises de rang inférieurs. Ces territoires montrent des environnements sociotechniques à forte compatibilité avec le VE. Il y a peu de stations essence, de transports publics et le stationnement y est facile. Les Micro VE sont chargés sur prises 220 V classiques – ce qui résout le problème d’infrastructures de charge – et permettent une véritable mobilité de proximité plus performante que les deux roues électriques. Mais les forces en faveur d’une légalisation du marché des Micro VE ont le potentiel de le détruire, injectant de la technologie et des normes, et donc augmentant les prix. Une opportunité, semble-t-il, pour les acteurs occidentaux maîtrisant le design-to-cost.Enfin, nous caractérisons la globalisation du programme VE de Renault en Chine, au sein de la triple alliance avec Nissan et le partenaire chinois Dongfeng, ainsi que l’ambidextrie organisationnelle qui l’accompagne. Après des tentatives « d’exploitation » de la gamme VE existante en Chine, le président de l’Alliance Renault-Nissan initie un projet « d’exploration », Kwid EV, un VE low cost pour la Chine. C’est l’occasion pour cette thèse de contribuer aux hypothèses initiales sur le bas du marché VE Chine et de caractériser l’hybridation de lignée qui s’opère chez Renault, entre lignée VE (Europe) et lignée low-cost (Kwid en Inde), entre deux parties de l’organisation auparavant disjointes. Le monde devient ainsi un terrain d’expérimentation pour l’innovation en réseau, avec des marchés tests comme la Chine. Il s’agit alors de réussir le premier coup avant d’innover à l’envers. / The electric vehicle (EV) market in China is booming, but Western manufacturers are struggling to deploy their models in the world’s largest automotive market. However, carbon credits generated by EV sales are necessary for the survival of their gasoline car business in this market. Thus, what are the high potential strategic opportunities for foreign manufacturers?In collaboration with Renault and based on five missions in China between 2012 and 2016, this CIFRE research first draws a state of the art of the opaque EV market in China, a market generated top-down by government initiatives and bottom-up by a low-cost and illegal EV market (Micro EV). We make a typology of models, usages, prices and deployment territories. While the subsidized market – except for premium cars – fails to appeal to consumers, it is instead at the bottom of the official market and within the illegal Micro EV market that a natural market is developing, with more than a million Micro EV sold, without purchase incentives, to private owners since 2009.In this specific institutional context and taking into account this double product and market uncertainty, we build on innovative design theories to develop a theoretical framework for strategic exploration based on the systematic combination of strategic variables and their evaluation. We identify two innovative routes not yet engaged by foreign manufacturers: "electric carsharing" and "low-cost VE".On the "electric car sharing" side, we compare Autolib’ (Paris) and United Journey (Shenzhen), two self-service stations-based systems that seem to pave the road to the mobility of the future and definitely attract the attention of Chinese authorities because of the technologies involved. However, in addition to the fragility of the business models, this opportunity seems difficult for foreign firms to pursue due to local protectionism and the complexity of public-private partnerships in China, often based on networks of informal institutions.On the "low cost EV" side, we are deepening our knowledge of the illegal micro EV market. A field survey in Shandong Province characterizes the market as well as the regulatory scenarios of its legalization. This market responds to real mobility needs in Chinese lower-tier cities. These territories’ socio-technical environments demonstrate strong compatibility with EV. There are fewer gas stations and public transportation systems than in big cities, and parking is easier. Micro EV are charged thanks to conventional 220 V outlets – which essentially solves the problem of charging infrastructures – and allow a true proximity mobility that is more efficient than electric two-wheelers. But the forces in favor of legalizing the Micro EV market have the potential to destroy it, injecting technology and standards, and thus raising prices. An opportunity, it seems, for Western players mastering design-to-cost methodologies.Finally, we characterize the globalization of Renault's EV program in China, within the triple alliance with Nissan and the Chinese partner Dongfeng, as well as the organizational ambidexterity that accompanies it. After attempts to "exploit" the existing EV range in China, the President of the Renault-Nissan Alliance initiates the launch of an "exploratory" project, Kwid EV, a low-cost EV for China. This is the opportunity for this research to contribute to the initial hypotheses about the lower-end of the Chinese EV market and to characterize the lineage hybridization that takes place at Renault, between the EV lineage (European EV) and the low-cost lineage (Kwid in India), between two disjoined parts of the organization. The world becomes a testing ground for networked innovation, with test markets like China. Then, the goal is to make this first shot succeed before reversing the innovation.
738

Une méthode hybride couplant la méthode des équations intégrales et la méthode des rayons en vue d'applications au contrôle non destructif ultrasonore. / A hybrid strategy combining the integral equation method and the ray tracing method for high frequency diffraction involved in ultrasonic non destructive testing.

Pesudo, Laure 06 October 2017 (has links)
Le Contrôle Non Destructif (CND) permet de sonder l’intérieur d’un milieu dans le but desurveiller son intégrité et son vieillissement. Assisté d’outils de simulation il permet de détecter, caractériseret localiser des défauts de structure du milieu inspecté mais sa fiabilité dépend de la précision des méthodesde simulation. Dans le cadre du CND ultrasonore, les méthodes usuelles (numériques et asymptotiques) sontbien souvent inadéquates pour simuler la diffraction par les défauts. On leur préfère des techniques hybrides.On propose dans cette thèse une nouvelle approche hybride pour la simulation numérique de la diffractionhaute fréquence en milieu étendu (configuration critique pour le CND). Combinant la méthode des équationsintégrales et la méthode des rayons, cette approche exploite le caractère multi-échelle du problème hautefréquence en proposant un modèle d’obstacle à deux échelles. Elle permet le calcul précis de la diffraction etla propagation rayon des champs. D’abord mise au point dans le cadre de la diffraction d’ondes acoustiquespar un obstacle de taille inférieure à la longueur d’onde (méthode barycentrique), l’approche est ensuiteétendue à des configurations de diffraction par des obstacles de l’ordre de la longueur d’onde grâce àl’introduction d’un partitionnement de l’unité de sa surface (méthode multi-centres). Pour accélérerl’approche hybride, on propose une procédure de résolution Online-Offline, basée sur un pré-calcul de lamatrice de diffraction associée à un ensemble réduit de directions d’incidence et d’observation et sur uneinterpolation polynomiale de ses vecteurs singuliers pour son évaluation dans des directions quelconquesd’émetteurs et de récepteurs. On étudie ensuite la stratégie dans le cadre de l’acoustique 3D puis on en faitune extension de principe à l’élastodynamique. On donne enfin un ensemble de pistes pour étendre l’approchehybride dans des cas de diffraction par un ou plusieurs obstacles pouvant être proches des bords du milieu. / Non Destructive Testing (NDT) aims at probing a medium to check its integrity and aging. Withthe help of simulation tools, it allows to detect, caracterize and locate flaws inside a material with a precisiondepending on that of the simulation methods. Usual numerical and asymptotic methods nevertheless often failat precisely computing diffraction for ultrasonic NDT. Hybrid approaches are thus prefered in this framework.In this thesis, we propose a new hybrid strategy combining the boundary integral equation method and raytracing to compute high frequency diffraction of an obstacle in a large medium (critical NDT configuration).This strategy allows to compute precisely the diffraction effects and to convert and propagate the diffractedfield as rays. The proposed strategy relies on a two-scale model of the diffracting obstacle. First developpedto simulate acoustic waves diffraction on an obstacle of size less than the wave length (barycentric method),the hybrid strategy is then extended to compute the diffraction by an obstacle of size some wave lengths(polycentric method) thanks to the introduction of a partition of unity of the obstacle surface. Besides, inorder to accelerate the hybrid approach, we propose an Online-Offline resolution procedure based on theOffline computation of the scattering matrix for a reduced set of incidence and observation directions and onthe use of a polynomial interpolation of its singular vectors for the Online evaluation of the scattering matrixfor any incidence and observation directions. We then study the possibility of extension of the hybrid strategyto 3D acoutics and elastodynamics. We finally give several perspectives for the adaptation of the approach todeal with diffraction by one or several obstacles potentially close to the propagating medium boundaries.
739

Population Dynamics and Genotypic Richness of the Threatened Acropora spp. and their Hybrid in the U.S. Virgin Islands

Nylander-Asplin, Hannah F 26 November 2018 (has links)
Since the 1980’s, there has been an unprecedented decline in the reef-building Caribbean corals, Acropora cervicornis and A. palmata, which has led to their listing as “threatened” under the U.S Endangered Species Act. Despite this protective status, these Acropora species continue to experience declines primarily attributed to disease, global climate change, and storm damage. Recent evidence suggests the hybrid of these threatened species (A. prolifera) is found at abundances similar to or higher than the parental species at many sites throughout the Caribbean. However, there is still much that is unknown as to how and why hybrids may be increasing in abundance at select sites. In 2007, scientists from NOAA NMFS established 9 permanent transects at three sites in the USVI to quantify fish diversity and coral tissue condition in A. cervicornis thickets. Over the years, they observed that A. prolifera seemed to be increasing in abundance on transects that were once dominated by A. cervicornis. This dataset provided a unique opportunity to investigate whether a shift from a threatened parental species to its hybrid may have occurred. This study has two objectives, (1) to quantify the change in A. cervicornis and A. prolifera percent cover and colony health over a 9-year period, and (2) to compare the genotypic diversity among the three Caribbean acroporids on and near the transects to determine the primary method of propagation, i.e., sexual versus asexual. For this study, I used transect photographs taken in March, July and November 2009, April 2012, and August 2017 to compare intra- and interannual variation in acroporid cover and colony health. Striking losses were observed in A. cervicornis cover between March 2009 and August 2017. At Thatch Cay, A. cervicornis declined from 25.7% to 8.9% between March 2009 and November 2009, but remained stable (10.2%) up to August 2017. Acropora cervicornis cover declined from 13.2% to 0% at Lovango Cay, and from 8.2% to 0% at No-Name Bay. At the one site (No-Name Bay) that A. prolifera was present during the original surveys of the transects, the percent cover remained relatively high and stable over the sample period. At No-Name Bay, A. prolifera percent cover (18.2%) was significantly higher than A. cervicornis (5.4%) by November 2009. It appears that A. prolifera expanded in the habitat left void by the decline in A. cervicornis. The general health of A. cervicornis based on the amount of healthy versus white and pale tissue appeared to decline at all sites between March 2009 and November 2009. To determine if the high percent cover on some transects was derived from asexual propagation or sexual recruitment, 139 tissue samples were collected in 2017 and genotyped using five microsatellite markers. No significant difference in genotypic richness (number of unique genotypes divided by the sample size) was observed among A. cervicornis (0.62), A. prolifera (0.64), and A. palmata (0.68). This suggests that the hybrid colonization is from multiple sexually derived individuals, not just asexual propagation from a rare hybridization event. High genotypic diversity, stable population abundance, and healthier colonies, suggest acroporid hybrids may become the primary habitat building coral of shallow reefs in the U.S. Virgin Islands. Due to considerable differences in morphologies between A. cervicornis and A. prolifera, it is unclear how a shift to the hybrid may affect the organisms that occupy acroporid structure and if the same ecological functions can be fulfilled.
740

Ecology of bacterioplankton specific to the oxygenated hypolimnia of deep freshwater lakes / 大水深淡水湖の有酸素深水層に特有な細菌の生態解明

Okazaki, Yusuke 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20953号 / 理博第4405号 / 新制||理||1633(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 中野 伸一, 教授 木庭 啓介, 教授 中川 尚史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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