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 22 for “"directional selection"”.
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A topic model based approach to inferring episodic directional selection in protein coding sequences
… immune response and drug therapy, (2.) it is directional in that only particular amino acid substitutions are favoured and (3.) it varies between genomic loci. Most previous models have ignored or inadequately addressed some of these phenomena. This work extends recent approaches to modelling …
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The effects of stress hormones on preferences for acoustic signals in female green treefrogs (Hyla cinerea) and barking treefrogs (Hyla gratiosa)
… are highly variable and characteristically under directional selection via mate choice by females. In <italic>H. cinerea<italic>, the probability of choosing male advertisement calls broadcast at high rates in dual speaker phonotaxis trials decreased as CORT dose and circulating CORT level …
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Genetic dissection of variability in cognitive and locomotor phenotypes using Drosophila melanogaster
… quantitative trait loci (QTL) mapping and directional selection methods to identify genomic regions contributing to olfactory learning and memory using an appetitive olfactory conditioning Y-maze behavior assay for phenotyping. After phenotyping 50 recombinant inbred lines (RILs) I …
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Investigations of physiological and competitive relationships of Elymus species related to establishment in the Great Basin, USA.
… natives may experience evolutionary changes. Directional selection for plant traits in restored populations may occur as a result of differential mortality related to the ability to acquire resources. The goal of this research was to determine what physiological traits of native perennial …
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The generalized inbreeding coefficient and the generalized heterozygosity index in a recurrent selection program
… In a finite population undergoing recurrent selection (self-select-intercross in succeeding generations) were investigated. It was noted that, in a population under selection, the inbreeding coefficient does not provide the experimenter with a measure of expected degree of variability; …
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Mechanisms Maintaining Additive Genetic Variance in Fitness in Red Squirrels
… to evolve, however, theory suggests that strong directional selection should erode additive genetic variance (Va) in fitness and limit future evolutionary potential. Sexual antagonism and temporal fluctuations in selection are mechanisms that could maintain Va in fitness. Maternal genetic effects …
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Sex Differences and the Evolution of Gene Expression
… biased genes, are enriched for signatures of directional selection at the gene expression level. By examining the evolutionary properties of gene-flanking regions on the X Chromosome, I find evidence that adaptive cis-regulatory changes are more likely to drive the expression evolution of …
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Quantifying evolution and natural selection in vertebrate noncoding sequence
… to identify varying patterns of natural selection. Many traditional methods of classifying directional selection have relied on models that categorize mutations as function-altering or neutral, and then comparing the rates of the two categories of mutations. The most well-known methods …
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Hard-wired for success? Unravelling genomic signatures in pollinators
… <br/>The fourth study investigated positive selection, detecting a higher number of genes evidencing positive selection in Pyrobombus compared to other lineages, which were enriched for small molecule metabolism functions. <br/>In the final study, the first whole genome resources were …
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Variation and the evolutionary drivers of diversity in the genus Paranthropus
… P. aethiopicus and P. boisei. Reconstructed selection vectors indicate that both positive and negative directional selection have driven diversification in mandibular and tooth dimensions and in the cranium, resulting in variable morphological responses including considerable evidence for …
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NO SIMPLE TRADEOFFS: CENTAUREA PLANTS FROM AMERICA ARE BETTER COMPETITORS AND DEFENDERS THAN PLANTS FROM THE NATIVE RANGE
… in its invaded range appear to exert strong directional selection on the weed's competitive and defense traits.
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NO SIMPLE TRADEOFFS: CENTAUREA PLANTS FROM AMERICA ARE BETTER COMPETITORS AND DEFENDERS THAN PLANTS FROM THE NATIVE RANGE
… in its invaded range appear to exert strong directional selection on the weed's competitive and defense traits.
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The Evolutionary Effects of Fishing: Implications for Stock Management and Rebuilding
… phenotypic variability. Fishing is a source of directional selection resulting in the directed removal of some phenotypes; however, many aspects of the evolutionary effects of fishing remain have yet to be described. In order to better understand the life-history and morphological changes that …
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Effects of habitat degradation on the evolutionary dynamics of populations in a rainforest cycad (Gymnospermae)
… 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, …
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Comparative and phylogenetic analysis of the early embryonic development in the phylum Nematoda
… should reveal whether these features are due to directional selection or other constraints, or whether the occurrence of these features is due to common ancestry.
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Comparative microbial genome analysis of lactobacilli
… I showed that conclusions about purifying versus directional selection across subclades was influenced by alignment strategy. In Chapter 5, I give a general discussion of how my thesis contributes to current literature, including future perspectives in the comparative genomics of lactobacilli.
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How Linkage Disequilibrium and Recombination Shape Genetic Variation Within and Between Species
… diversity at a given locus may be reduced by directional selection on the locus, or by selection on neighboring linked loci. Recombination rates and nucleotide diversity are positively correlated across loci within many species, which can be explained by linked selection reducing nucleotide …
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Testing the Major Theories Concerning the Evolution of Sex using Experimental Evolution
… lines with increased mutation rates under both directional and stabilising selection for approximately 300 generations. The sexual lines increased in fitness significantly more quickly than the asexual lines under directional selection, regardless of mutation rate. In contrast, no lines, …
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Expression of fluctuating asymmetry in primate teeth: Analyzing the role of growth duration
… deviations from bilateral symmetry without any directionality between sides. Extended periods of growth may provide a `window of opportunity’ for growing body structures to accumulate perturbations resulting in elevated DN, manifested as FA. In comparison to other mammalian species, primates …
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Thermal adaptation in butterflies: patterns, significance and mechanisms
… to such phenotypic patterns, a contribution of directional selection on traits related to fitness is inferred from clinal variation in such traits, and analyzing such variation has consequently become a key element in investigating adaptive evolution. In L. tityrus, altitudinal variation in …
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