Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 131 for “"selective pressure"”.
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Evolutionary trade-offs and adaptive phenotypic plasticity under multidimensional selective pressure
… However, predicting how phenotypes respond to selective pressure via a quantitative theory of evolution remains challenging due to a number of factors complicating the genotype to phenotype map. Genetic architecture presents an internal source of complexity, constraining adaptive responses by …
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A cross-over randomised controlled trial of selective pressure impressions for lower complete dentures and laboratory investigations into impression pressure variation
… The literature review from Part I suggested that selective pressure impressions for complete dentures required evidence on three levels; firstly, in-vitro evidence on the numerous factors that affect pressure, secondly evidence that within a specific impression technique the pressure is …
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The transmitted HIV-1 subtype C: characterization of the transmitted/founder full-length virus genome and the influence of early immune selective pressure on virus replication
… was attributed to CD8+ cytotoxic Tlymphocyte pressure, 35% to antibody-mediated pressure, 16% to reversion and 9% could not be classified. The rate of sequence diversification and number of sites evolving under immune selection was highest in nef. The majority of evolving CD8+ cytotoxic …
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Plastid Genome Evolution in the Parasitic Genera Cuscuta (Convolvulaceae) and Krameria (Krameriaceae)
… is rare across green plants due to the degree of selective pressure imposed by primary production. This is particularly true for plastid genomes (plastomes) given that chloroplasts are the primary site of photosynthesis in the cell and that plastomes encode key portions of the photosynthetic …
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AERIAL WARFARE BETWEEN BATS AND MOTHS: EFFICACY OF ACOUSTIC APOSEMATISM, FLIGHT BEHAVIORS OF UNPALATABLE PREY, AND TWO NOVEL ANTI-BAT STRATEGIES
… (Erebidae: Arctiinae) have experienced intense selective pressure from echolocating, insectivorous bats for nearly 65 million years. In response, they have evolved a suite of remarkable defenses to deal with their would-be predators. Three key innovations underlie the success of the tiger moth …
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The Evolution of Fitness After Prolonged Sperm Storage
… I introduced extended mating deprivation as a selective pressure to experimentally evolve lines of D. melanogaster for characters related to mating and postcopulatory sexual selection. Evolution of the mate-deprived lines over several dozen generations demonstrated that restricted sexual access …
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Ligand discrimination and inhibition of heme iron autooxidation by myoglobin: Site-directed mutagenesis of a synthetic gene
Globins have evolved under strong selective pressure to overcome the natural tendency of a free heme prosthetic group to bind carbon monoxide (CO) 1000-fold more tightly than atmospheric dioxygen (O$\sb2$). Without protein-directed discrimination between these ligand molecules, the basal production …
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Ecological Studies on the Microbial Upgrading of Straw
… presence of free ammonia can produce a unique selective pressure in favour of C cinereus which was not observed using other nitrogen sources at an elevated pH. The optimum levels of ammonia and temperature required to bring this about were investigated, together with the nature of this …
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A new theoretical treatment of pathogen and host evolution
… sexual selection can further amplify the selective pressure on the host to overcome parasite infection. I focus on certain types of parasites, those that can impair the activity of the host immune function and I show that the effect of sexual selection can actually reduce the selective …
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The tree alignment model : algorithms, implementations and applications for the analysis of RNA secondary structures
… a lot of unknown ones today). In this case the selective pressure acts on the structure, which conserves structure instead of sequence. In spite of all its success, pure sequence based comparative analysis gets to its limit when structural conservation is of interest. In this thesis, I focus on …
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Investigating the lignocellulolytic gut microbiome of huhu grubs
… was observed to have a ‘bottleneck effect’ or selective pressure on the fungal gut community. The gut bacterial community of huhu grubs reared on cellulose or lignocellulose diets seemed to be unaffected by the selective pressure of the diet, and no significant change in the bacterial community …
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A topic model based approach to inferring episodic directional selection in protein coding sequences
… as HIV and influenza, evolve in response to the selective pressures of their host environments accumulating changes in their genomes that offer fitness benefits. This selective pressure is characterised by three properties: (1.) it is episodic, tracking changes in the adaptive immune response and …
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Plant water relations along a rainfall gradient, between the succulent Karoo and Mesic Mountain Fynbos, in the Cedarberg Mountains, near Clanwilliam, South Africa
… temperatures are hypothesized to be the primary selective pressures. In Australia and South Africa low soil nutrients are thought to be important, as they are in defining the structurally similar heathlands found with a range of climatic types. The fynbos vegetation in an area with a …
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Optimal bioeconomic management of changing marine resources
… a multispecies fishery, when harvest creates a selective pressure on dispersal, and when rising temperatures cause changes in vital rates. I explore this last case in both deterministic and stochastic environments, and also allow the harvester to learn about unknown parameters of the stock …
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CRISPR-based approach enables targeted random nucleotide diversification in mammalian cells
… hEvolvR to restore antibiotic resistance under selective pressure. Furthermore, hEvolvR allowed us to generate variants of SARS- CoV-2 Spike-PP protein with restored fusogenic activity as visualized in high throughput imaging screening.
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Optimal bioeconomic management of changing marine resources
… a multispecies fishery, when harvest creates a selective pressure on dispersal, and when rising temperatures cause changes in vital rates. I explore this last case in both deterministic and stochastic environments, and also allow the harvester to learn about unknown parameters of the stock …
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Studying the Competence Regulon Quorum Sensing Circuity in Streptococcus mitis
… survival of the bacteria, thus minimizing the selective pressure for resistance development. Streptococcus mitis , a pathogenic bacterium, utilizes the comABCDE competence regulon QS circuity. However, the competence stimulating peptide (CSP), the signaling molecule, that is responsible for QS …
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Biomarker Accessible and Chemically Addressable Mechanistic Subtypes of BRAF Melanoma
… sought to identify therapeutic targets that are selectively required for tumorigenicity in the presence of pathological ERK1/2 signaling. Such targets could be leveraged in jiu jitsu fashion to breach selective pressure to engage any of the many BRAF-independent ERK1/2 pathway activation …
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Extinction of Chromosomes due to Specialization is a Universal Occurrence
… to sex chromosomes, or if it conveys a potential selective advantage aside from sexual antagonism. We examined the evolution of mammalian orthologs to determine if the selective forces that led to the degeneration of the Y chromosome are unique in the genome. The results of our study suggest these …
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