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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.
41

Hornen blev till kam : Kammars råmaterial och ornamentik som aspekter i ett icke-verbalt identitetsspråk / The antlers turned into combs : Comb raw material and decoration as aspects for a non-verbal identity-language

Hedlund, Linda January 2023 (has links)
Denna studie undersöker och diskuterar möjligheterna som finns för att tala om ett icke-verbalt visuellt identitetsspråk för kammaterial från perioden ca 700–900 e.v.t. Studien utgår från och analyserar arkeologisk forskning som utförts i olika miljöer. Syftet är att se till potentialen som finns för vidare forskning gällande kammar, råmaterial och ornamentiks delaktighet i identitetsprocesser. Genom att studera vardagliga föremål som kammar med nya metoder och teknologi ökar möjligheterna att studera subtila sociala och kulturella fenomen. Undersökningen ämnar därför att även belysa hur nya frågor kan tillkomma och ställas till äldre väl undersökt material. / The aim of this study is to discuss and explore the possibility of a non-verbal language based on visuality in comb material dating to c. 700-900 C.E. The study analyses different archaeological research done in different locales within and outside of Scandinavia. The aim is to understand the potential of further research into identity studies based on previously made associations and interpretations regarding combs, raw material and decoration. Through new technologies, the study of everyday objects of the past can be given new context and meaning. This study aims to bring forth the potential in old well documented material.
42

Improving specimen identification: Informative DNA using a statistical Bayesian method

Lou, Melanie 04 1900 (has links)
<p>This work investigates the assignment of unknown sequences to their species of origin. In particular, I examine four questions: Is existing (GenBank) data reliable for accurate species identification? Does a segregating sites algorithm make accurate species identifications and how does it compare to another Bayesian method? Does broad sampling of reference species improve the information content of reference data? And does an extended model (of the theory of segregating sites) describe the genetic variation in a set of sequences (of a species or population) better? Though we did not find unusually similar between-species sequences in GenBank, there was evidence of unusually divergent within-species sequences, suggesting that caution and a firm understanding of GenBank species should be exercised before utilizing GenBank data. To address challenging identifications resulting from an overlap between within- and between species variation, we introduced a Bayesian treeless statistical assignment method that makes use of segregating sites. Assignments with simulated and <em>Drosophila</em> (fruit fly) sequences show that this method can provide fast, high probability assignments for recently diverged species. To address reference sequences with low information content, the addition of even one broadly sampled reference sequence can increase the number of correct assignments. Finally, an extended theory of segregating sites generates more realistic probability estimates of the genetic variability of a set of sequences. Species are dynamic entities and this work will highlight ideas and methods to address dynamic genetic patterns in species.</p> / Doctor of Philosophy (PhD)
43

Taxonomical study of predatory and plant-parasitic mites associated with South African Solanaceae / Candice Ceustermans

Ceustermans, Candice January 2015 (has links)
Plant-feeding mites represent major pests in agriculture that are of importance to crops world-wide, as large populations of mites reduce the quality and quantity of yields. Alternatives to the use of pesticides are needed due to their negative effects and bio-control agents (predatory mites) remain advantages as they suppress spider mites and other plant pests. This study aims to determine species status of plant-feeding and predatory mites on plants of the family Solanaceae and to apply morphological and molecular data to determine phylogenetic relationships among economically important Phytoseiidae, Stigmaeidae and Tetranychidae. The material for this study was collected through plant beating and specimens were preserved in 75% and 96% ethanol respectively and mounted in Heinz’s PVA medium on microscope slides. A survey was conducted during peak seasons to provide enough samples of pest and predatory species. Morphological analysis was performed and initial results indicate that 94% of the species identified were parasitic and 6% were predatory, which led to a predator:prey ratio of 1:17, where Tetranychus evansi Baker & Pritchard had the highest frequency of appearance. A modified Qiagen DNeasy tissue kit extraction protocol was used and Polymerase Chain Reaction was performed to amplify ribosomal ITS and mitochondrial COI gene fragments. The nucleotide sequence of a 700-bp fragment for ITS was determined by direct sequencing as well as for a 700-bp and 800-bp fragments for COI. The resulting data included 4 isolates that corresponded morphologically and molecularly with Phytoseiidae and 10 with Stigmaeidae. The phylogenetic trees agreed with the morphological data. For species that lack morphological descriptions in GenBank and are not placed within expected clades, one has to accept the possibility of miss identification and highlights the need to combine morphological and molecular approaches to guarantee solid species diagnosis. Ultimately, Solanaceae contain various parasitic mites, but predators seem low in numbers. This could be problamatic in finding effective bio-control agents. / MSc (Zoology), North-West University, Potchefstroom Campus, 2015
44

Taxonomical study of predatory and plant-parasitic mites associated with South African Solanaceae / Candice Ceustermans

Ceustermans, Candice January 2015 (has links)
Plant-feeding mites represent major pests in agriculture that are of importance to crops world-wide, as large populations of mites reduce the quality and quantity of yields. Alternatives to the use of pesticides are needed due to their negative effects and bio-control agents (predatory mites) remain advantages as they suppress spider mites and other plant pests. This study aims to determine species status of plant-feeding and predatory mites on plants of the family Solanaceae and to apply morphological and molecular data to determine phylogenetic relationships among economically important Phytoseiidae, Stigmaeidae and Tetranychidae. The material for this study was collected through plant beating and specimens were preserved in 75% and 96% ethanol respectively and mounted in Heinz’s PVA medium on microscope slides. A survey was conducted during peak seasons to provide enough samples of pest and predatory species. Morphological analysis was performed and initial results indicate that 94% of the species identified were parasitic and 6% were predatory, which led to a predator:prey ratio of 1:17, where Tetranychus evansi Baker & Pritchard had the highest frequency of appearance. A modified Qiagen DNeasy tissue kit extraction protocol was used and Polymerase Chain Reaction was performed to amplify ribosomal ITS and mitochondrial COI gene fragments. The nucleotide sequence of a 700-bp fragment for ITS was determined by direct sequencing as well as for a 700-bp and 800-bp fragments for COI. The resulting data included 4 isolates that corresponded morphologically and molecularly with Phytoseiidae and 10 with Stigmaeidae. The phylogenetic trees agreed with the morphological data. For species that lack morphological descriptions in GenBank and are not placed within expected clades, one has to accept the possibility of miss identification and highlights the need to combine morphological and molecular approaches to guarantee solid species diagnosis. Ultimately, Solanaceae contain various parasitic mites, but predators seem low in numbers. This could be problamatic in finding effective bio-control agents. / MSc (Zoology), North-West University, Potchefstroom Campus, 2015
45

Molekulargenetische Untersuchungen an Überresten präkolumbischer Neuwelt-Camelidae aus dem Palpa-Tal (Peru) / Moleculargenetic investigations of precolumbic remains of the New World Camelids from the Palpa valley (Peru)

Renneberg, Rebecca 29 April 2008 (has links)
No description available.
46

DNA Barcoding på Växter : Hur kan man använda genetisk barcoding i olika biologiska fält och i den gymnasiala undervisningen? / DNA Barcoding on Plants : How to conduct DNA barcoding in different biological fields and in high school settings

Ibrahimovic, Ida January 2019 (has links)
Syftet med litteraturstudien är att sammanfatta vilken gensekvens som används vid genetisk barcoding av växter och hur väl metoden i fråga tillämpas i tre biologiska yrkesområden: dietanalyser i ekologin, analys av pollensporer i forensisk biologi samt analys av uråldrigt DNA (ancient DNA) i paleontologin. Vidare var det även av intresse att se hur genetisk barcoding kan användas i den gymnasiala undervisningen och hur väl den passar in med de svenska styrdokumenten för skolan. Hur elever har gynnats av den valda metoden samt vilka begränsningar som har uppstått har också berörts. Litteraturstudien baseras på vetenskapliga artiklar som har sökts fram med de nedan listade nyckelorden. Resultaten visar att en kombination av gensekvenser, däribland rbcL, matK, trnH-psbA och ITS, fungerar bäst vid identifiering av växter. I dagsläget är genetisk barcoding fortfarande i utvecklingsfasen, där metoden begränsas av antalet referenssekvenser i databaserna, vilket gör det svårt att utesluta morfologiska identifieringsmetoder i de tre yrkesområdena. Vid användning av barcoding i den gymnasiala undervisningen visar det sig att det stämmer väl överens med de svenska styrdokumenten och ökar elevers intresse för de naturvetenskapliga ämnena, då de kan bidra med värdefull forskning genom tillägg av referenssekvenser i databaserna. De största begränsningarna är att det blir ett stort arbetslass för läraren, att läraren i fråga måste vara bekväm med de olika laboratiska momenten och att skolan ska ha tillgång till nödvändig apparatur. / The purpose of the literature study is to conclude which gene sequences are being used in DNA barcoding on plants and how the method in question is being used in three different biological occupations: diet analysis in ecology, analysis of pollen in forensics and analysis of ancient DNA (aDNA) in paleontology. Further it was also of interest to study how DNA barcoding can be used in high school settings and how the method correlates with the Swedish curriculum. How pupils have benefited from the chosen method and what limitations have arisen have also been touched upon. This literature study is based on scientific articles that have been sought with the keywords listed below. The results show that a combination of gene sequences, including rbcL, matK, trnH-psbA and ITS, works best in plant identification. At present, genetic barcoding is still in the developmental phase, where the method is limited by the number of reference sequences in the databases, which makes it difficult to exclude morphological-based methods in the three occupational fields. When using barcoding in upper secondary education it turns out that it’s in good agreement with the Swedish curriculum and increases the students' interest in the scientific subjects, since they can contribute with genuine research when adding reference sequences in the databases. The main limitations are the workload for the teacher, the teacher in question must be comfortable with the different laboratory steps and that the school must have access to necessary equipment.
47

Species delimitation in the Choristoneura fumiferana species complex (Lepidoptera: Tortricidae)

Lumley, Lisa Margaret 11 1900 (has links)
Species identifications have been historically difficult in the economically important spruce budworm (Choristoneura fumiferana) pest complex. Morphological, ecological, behavioural, and genetic characters have been studied to try to understand the taxonomy of this group, but diagnostic character states differ in frequency rather than being complete replacements between each species. I developed a morphology-based character system that focuses on forewing colour components (Chapter 2), as well as eight simple sequence repeats (SSRs, also referred to as microsatellite markers) (Chapter 3). I tested these along with a 470 bp region of COI mitochondrial DNA (mtDNA) (Chapter 2, 4) to determine their congruence with putative species that were identified by adaptive traits (larval host plant, length of larval diapause, larval and adult morphology, pheromone attraction, distribution). The morphometrics system was effective for identification of the five species tested, with only slight overlap between C. fumiferana and C. biennis. MtDNA distinguished C. fumiferana and C. pinus pinus, but the remaining species shared haplotypes. SSRs distinguished four species (C. fumiferana, C. pinus pinus, C. retiniana, C. lambertiana) but the remaining four species that were included in this survey (Chapter 4) remained mixed within two populations. There was evidence for hybridization between several species pairs. I also conducted a detailed study (Chapter 5) in Cypress Hills, an isolated remnant coniferous forest in western Canada, where identifying individuals from the Choristoneura fumiferana complex has been impossible due to the unusual ecogeographic characteristics of the area. I integrated data on behaviour, ecology, morphology, mtDNA, and SSRs, comparing Cypress Hills populations to those from other regions of North America to determine which species they resembled most. I delimited at least three populations, resembling C. fumiferana, C. occidentalis and C. lambertiana. Adult flight phenology, along with pheromone attraction, were identified as major isolating mechanisms between these populations. My studies highlighted the importance of integrative taxonomy for understanding species boundaries. Their patterns of differentiation suggest that spruce budworm species have recently diverged via natural selection in spite of some gene flow. Overall, this work is intended to contribute to more accurate identification of specimens and a better understanding of the evolutionary processes that drive speciation. / Systematics and Evolution
48

Species delimitation in the Choristoneura fumiferana species complex (Lepidoptera: Tortricidae)

Lumley, Lisa Margaret Unknown Date
No description available.
49

Systematics of Bonatea (Orchidaceae) : species boundaries and phylogeny.

Ponsie, Mariaan E. January 2006 (has links)
Bonatea Willd. (Orchidaceae: Habernariinae) is a small genus confined to the African continent and Arabia. Phylogenetic and morphometric analyses were undertaken in order to evaluate phylogenetic relationships and species delimitations within Bonatea. In the phylogenetic analyses, little congruence was found between ITS and matK molecular data, while morphological results were largely congruent with those of the ITS region. There is little sequence variation within and between Bonatea species, which could indicate a recent and rapid radiation. The generic characters for Bonatea were reevaluated. Bonatea is closely related to Habenaria but differs in having a galeate middle rostellum lobe that is clearly separated from the vertical anther thecae. By contrast, species of Habenaria have short anthers that are slightly arcuate and flank the rostellum. Morphometric analyses were used to determine taxon boundaries within the Bonatea speciosa and Bonatea cassidea complexes, respectively. Principle component and cluster analyses of morphological variation support the recognition of Bonatea antennifera Rolfe, Bonatea boltonii (Harv.) Bolus and Bonatea speciosa (L.f.) Willd. as distinct species. Morphological evidence supports the inclusion of Bonatea porrecta (Bolus) Summerh. and Bonatea volkensiana (Kraenzl.) Rolfe in the B. speciosa c1ade and this is corroborated by molecular data for the former. Clinal variation in petal lobe dimensions and colour across the distribution range of Bonatea cassidea Sond. encompasses the taxon Bonatea saundersiae (Harv.) T.Durand & Schinz, which is reduced to synonymy. Bonatea saundersioides (Kraenzl. & Schltr.) Cortesi, the sister species to B. cassidea, also exhibits colour variation in its petals. A revision of Bonatea is presented recognizing 14 species. Bonatea eminii (Kraenzl.) Rolfe was excluded due to insufficient information. Full descriptions are provided with diagnostic characters and distributional maps. Bonatea bracteata G.McDonald & McMurtry and Bonatea tentaculifera Summerh. are removed from Bonatea based on their rostellum structure which is inconsistent with the revised generic concept. Bonatea bracteata was transferred as Habenaria transvaalensis Schltr. and B. tentaculifera was renamed Habenaria bonateoides M.Ponsie, as the specific epithet is currently occupied within Habenaria. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2006.
50

Assessing the diversity of agrobacterial populations / Évaluation de la diversité des populations d'Agrobacterium

Shams, Malek 19 December 2012 (has links)
Les bactéries du genre Agrobacterium forment un ensemble taxonomiquement diversifié composé de nombreuses espèces, présent dans la plupart des sols et des rhizosphère. Les agrobactéries sont le plus souvent anodines voire stimulatrices de la croissance des plantes. Par contre, celles qui hébergent un plasmide Ti induisent la maladie de la galle du collet à de nombreuses plantes d'intérêt agronomique. Dans ce contexte, nous avons d'une part donné l'état actuel des connaissances sur la taxonomie du genre Agrobacterium, et nous avons fait une revue des méthodes d'isolement et de typage de ces bactéries. D'autre part, nous avons cherché à mettre au point des méthodes d'identification rapides et fiables des différentes espèces d'agrobactérie. La méthode de MALDI-TOF MS a permis d'identifier les espèces mais elle n'était pas assez résolutive pour typer des souches et encore moins la présence de plasmides Ti dans les isolats. Nous avons alors développé des amorces de PCR spécifiques de 17 espèces, du genre Agrobacterium et de la famille Rhizobiaceae. Ces amorces se sont révélées efficaces pour identifier les bactéries cultivées et aussi pour détecter leur présence dans des communautés microbiennes. Nous avons utilisé ces outils pour étudier la répartition des agrobactéries à l'échelle d'un pays, d'une station et entre sols nus et sols rhizosphériques en utilisant soit des isolats soit des ADN extraits des différents environnements. Enfin, nous avons montré que le clonage-séquençage ou le séquençage à haut débit d'amplicons obtenus à partir d’ADN de communautés microbiennes nous permettaient de connaître la diversité des populations d'agrobactéries / Agrobacterium are Alphaproteobacteria common in most soils that closely interact with plants in two respects. Firstly, they are rhizospheric bacteria saprophytically living in the rhizosphere of numerous plants and they are likely beneficial to plants. Secondly, when they harbor a dispensable Ti plasmid (i.e. tumor inducing plasmid), agrobacteria are plant pathogens able to cause the crown gall disease to most dicots and gymnosperms and some monocots. An epidemiological survey of crown gall thus also requires expert determination of the Agrobacterium taxonomy. In this thesis we evaluated the usefulness of MALDI-TOF MS technique as a high throughput tool to determine and classify agrobacteria. Then we set up a recA-based PCR method to accurately and exhaustively assess agrobacterial diversity either of isolated agrobacteria or directly in various biotopes. We applied standard biochemical, recA-based and Ti plasmid-based identification methods to study the prevalence of pathogenic and non-pathogenic agrobacteria at the country and local scales. Finally, we tested whether analyzing the internal composition of recA amplicons could be a way to directly assess the micro-diversity of agrobacterial populations using cloning sequencing or pyrosequencing approaches. The later methodology was applied to establish the actual field diversity of Agrobacterium and to evaluate whether plant genotypes differentially select agrobacteria in their root systems, providing first data upon biotic factors shaping the population structure of agrobacteria

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