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 56 for “"Purifying selection"”.
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Evolutionary analyses of HIV-1 protein-coding sequences : adaptation to host cytotoxic immune responses and purifying selection at synonymous sites
This thesis exposes previously ignored evolutionary characteristics of the synonymous sites of virus nucleotide sequences and contributes new findings to the understanding of the evolution of HIV-1 in relation to the human immune response.
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Intra-tumor heterogeneity and evolution
… can affect plastic phenotypes, and the role of purifying selection in cancer evolution. Different cell states or phenotypes have been observed within tumors, and they are associated with treatment resistance and metastasis. The observation that these phenotypes are plastic leads to a conundrum: …
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Patterns of Selection In Hepatitis C and Hiv
… and HCV-1b) showed evidence, not only of past purifying selection, but also of abundant slightly deleterious nonsynonymous variants subject to ongoing purifying selection. In the case of both HCV-1a and HCV-1b, the NS3 protein (with protease and NTPase/helicase activity) demonstrated a high …
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Evolutionary Genetics of Dictyostelids: Cryptic Species, Sociality and Sex
… of sequences. The removal of these mutations, purifying selection, should preserve nucleotide content. I used the genomes of D. discoideum and Plasmodium falciparum identify classes of sequences that should be under different amounts of purifying selection and compared their nucleotide …
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Speciation genes in native New Zealand leafroller moths
… EF-1 and TPI ). These loci show evidence of purifying selection and typically are not reciprocally monophyletic for P. octo + P. excessana and C. obliquana + C. herana. PBP1 is no better at recovering monophyly of species groups than any of the neutral genes. The phylogenetic patterns are …
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The evolutionary impacts of secondary structures within genomes of eukaryote-infecting single-stranded DNA viruses
… analyses involving the detection of natural selection, sequence co-evolution, and genetic recombination, it is possible to both validate the existence of, and infer the biological importance of, computationally predicted structures. Here I implement and deploy free bioinformatics tools to (1) …
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Molecular ecology and hierarchical models elucidate chronic wasting disease dynamics
… and the likely force of natural selection acting on it, by analyzing genetic diversity both within and between species within Class Mammalia. We accessed Prnp nucleotide sequences of a large number of mammalian species from GenBank. We undertook three distinct analyses of these …
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Differential Selection Pressure Among Duplicated Genes In Teleosts
… organisms with new genetic material subject to selection. Using myo5, rab11, and rab27 gene families as models, I examined the evolutionary rate differences among duplicated genes and whether selective forces (e.g. purifying selection or positive selection) could be identified in one or both …
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The Molecular Evolution of the Serotonin System in Macaques (MACACA): a Detailed Survey of Four Serotonin-Related Genes
… discern which evolutionary force – positive selection, balancing selection, purifying selection, or random genetic drift – is most likely to have acted on these genes. Three out of the four genes (HTR1B, TPH2, and SLC6A4), show a low level of overall genetic variation within the coding …
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Natural Selection on S-Linked Genes in Turnera (Passifloracease)
… were adopted to explore the signatures of selection on S-linked genes in distylous Turnera. While dN/dS-based results revealed pervasive purifying selection at the S-locus in Turnera, average nucleotide diversity and sequence polymorphism measures were found to be elevated in two S-linked …
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Bioinformatic studies of small disulphide-rich proteins (SDPs)
… structure. The analysis suggested heterogeneous selection pressure at different regions within the Pot II domains. As opposed to purifying selection over the cysteine scaffold that is expected, some evidence for positive selection on the reactive site is presented, illustrating the power and …
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Patterns of Archaic Hominin DNA in Modern Human Genomes
… event. I also present signatures of both purifying selection against Neanderthal sequence in modern humans, and selection for other, beneficial Neanderthal alleles. In a separate analysis, I show that the inferred parameters of the introgression event are not influenced by differing …
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Characterizing the effect of mutation recombination and reassortment on the genetic diversity of African horse sickness virus genomes
… a period of more than 60 years. The effects of selection, substitution rate and recombination over time were determined. African horse sickness virus isolates from the 1960’s to 2014, archived at the OIE World Reference Centre for AHSV and BTV at the ARC-OVI were propagated in cell cultures, …
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Impacts of Habitat, Resource Addition, and Predator Exclusion on Rodent Community Structure and Hantaviruses in the Neotropics
… and entry. There was evidence of strong purifying selection acting on both genomic segments. There was no evidence of positive selection. Despite there being evidence of strong purifying selection, genetic diversity differed significantly by habitat type. Diversity was higher in the least …
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The evolution of immune genes in tsetse flies (Glossina) and insights into tsetse-symbiont-trypanosome interactions
… Def and TLRs are governed by strict Darwinian selection. A wild population sample of Glossina morsitans morsitans illustrated differing levels of nucleotide variation in each gene, Def being the least polymorphic (n = 8) and TLR2 being the most (n = 22). All genes indicated a recent population …
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The ancient and recurrent evolution of Apobec3 antiviral activity in primates
… has developed that drives continuous rounds of selection for beneficial mutations in restriction factor genes and their viral antagonists. Because viruses can evolve faster than their hosts, the modern-day vertebrate innate immune system is optimized, for the most part, to defend against ancient …
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Adaptive metabolic gene clusters as toolkits for chemical innovation: Investigation of the origin of the avenacin gene cluster for synthesis of defense compounds in oats
… content and exon-intron structures changes under purifying selection on amino acid sequences. Syntenic study of the triterpene biosynthetic gene families reveals the ancestral triterpene biosynthetic OSC/CYP51 gene pair found in the �-WGD event. Finally, the evolutionary model of the avenacin …
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Investigating the relative influence of genetic drift and natural selection in shaping patterns of population structure in Delphinids (Delphinus delphis; Tursiops spp.)
… selected by investigating signals of positive selection in both mammals and cetaceans. No population structure was found in the European common dolphin for neutral microsatellite loci, in contrast to what is observed in other sympatric cetacean species. The previously described differention of …
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Network based analysis of genetic disease associations
… new, such variants have not been subject to purifying selection, and therefore may be particularly pertinent for neuropsychiatric disorders and other diseases with greatly reduced fecundity. Recently, several researchers have made great progress towards uncovering the genetics behind autism …
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Complex evolution of mitochondrial genomes: lessons from salamanders
… requirements among tetrapods, experience weaker purifying selection on protein-coding sequences than do frogs, a comparable amphibian clade with higher metabolic rates. In contrast, there is no evidence for weaker selection against mitochondrial genome expansion in salamanders. Together, these …
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