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 32 for “"Artificial selection"”.
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Swimming in four goldfish (Carassius auratus) morphotypes: understanding functional design and performance through artificial selection
Although artificially selected goldfish exhibit swimming performance decrements, with the most derived morphotypes more affected, they can be utilized to explore functional design and movement pattern principles in aquatic vertebrates. Drag, steady swimming kinematics (tailbeat frequency, …
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Selection for Body Weight in Chickens: Resource Allocations and Scaling
… responses to 54-generations of divergent selection for 8-week body weight (BW) and of BW at other ages and reproductive traits. Evaluated first was the influence of scaling on phenotypic responses to selection, phenotypic correlations of means and standard deviations, and unadjusted vs. …
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GENETIC DIVERSITY AND LINKAGE DISEQUILIBRIUM IN WILD SOYBEAN, LANDRACES, ANCESTRAL, AND ELITE SOYBEAN POPULATIONS
Domestication, founder effects, and artificial selection can impact populations by reducing genome diversity and increasing the extent of linkage disequilibrium (LD). To understand the impact of these genetic bottlenecks and selection on sequence diversity and LD within soybean [Glycine max (L.) …
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DNA Methylation and Genetic Divergence Associated with an Inducible Defensive Response in Mimulus guttatus
… sequence data from an experiment involving artificial selection for increased trichome production. Results indicate that epigenetic inheritance of the damage response in a particular RIL is associated with 59 differentially methylated regions. Relevant functions, including anatomical …
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Defining Mechanisms Contributing to Porcine MHC Class II Diversity
… to the domestic populations may suggest relaxed selection in the domestic populations at the DQB locus. Taken together, these data suggest that MHC polymorphisms have been selectively maintained, possibly by balancing selection, having overcome the effects of nonselective factors, artificial …
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Hypothalamic Mechanisms of Food Intake in Birds
… Broiler type chickens have undergone intense artificial selection for traits that promote rapid growth, consequently driving them to consume feed incessantly. It is hypothesized that broiler type chickens lack a mechanism that signals satiety, causing them to eat significantly more than layer …
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Insect Development and Evolution: Perspectives on Individual and Colony-Level Phenotypes
… spots, I present the results of a series of artificial selection experiments that highlight the species’ capacity for phenotypic evolvability. I then detail how changes in Wnt expression can lead to the evolution of bold phenotypes, and show that pterin pigments provide the primary source of …
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Are Large Dogs Smarter Than Small Dogs? Investigating Within Species Differences in Large and Small Dogs: Spatial Memory
… abilities. Dogs have undergone intensive artificial selection yielding distinctive breeds which differ both phenotypically and behaviorally. Breed based cognitive differences have not been found but some studies suggest there may be differences in broader categories such as working …
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Dissecting the Genetic Basis of Convergent Complex Traits Based on Molecular Homoplasy
… significantly relaxed during domestication for artificial selection. Overall, my thesis has resulted in a novel approach for studying convergent complex traits and provided critical insights into the evolution of vocal learning specifically, and complex traits generally.</p>
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Habit Preferences and Fidelity in the Cotesia Flavipes Complex (Hymenoptera: Braconidae): Current Preferences and the Potential for Change Through Learning and Selection
… of the adult wasp. Moreover, through an artificial selection regimen, I show that these wasps are unlikely to shift plant preferences through natural selection. Given my results, I argue that laboratory testing can yield a useful, and accurate picture of parasitoid behavior prior to …
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Comparative Analysis of Rhizosphere and Endosphere Microbiome of Different Blueberry Species (Vaccinium sp.)
… We hypothesized that interspecific crosses and artificial selection have significantly changed the microbiome of the blueberry and it has affected the overall community. We tested the hypothesis by comparing the microbiome and metagenome of five different species of blueberry comprising both …
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Applied genomics toward targeted improvement of soybean
… regions of the genome which have experienced artificial selection during US breeding efforts and found that over 60 percent of genes are fixed or nearly fixed for a single allele. Taken together, these data will facilitate breeder selection for appropriate maturity in their programs and define …
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Direct selection on lifespan in Drosophila Melanogaster to elucidate the mechanisms of longevity
Artificial selection can be used to create model organisms tailored for a specific research question. Selection experiments using Drosophila have been a prominent aspect of ageing research over the last 40 years, being used to elucidate the evolutionary roots of ageing, as well as the mechanisms …
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Analysis of Behavior in Populations of Swimming Microbes
… In addition, we performed experiments using artificial selection that provided evidence that this low dimensional representation may be of biological relevance.</p>
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Loblolly Pine Genetics Structure Its Mycorrhizal Community
… a multitude of biotic and abiotic environmental selection pressures. The ability of a population to persist in or adapt to its environment is heavily influenced by the genetic underpinnings of the traits involved. Thus, in order to understand patterns in current plant populations, and to predict …
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Ecological consequences of genetic variation in foraging behaviors of a predatory mite
… olfactory response of predatory mites. Through artificial selection I documented additive genetic variation in all four traits. After relaxation of selection, high-level phenotypes were stable compared to their low counterparts. There were significant genetic correlations between some of the …
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Nitrogen Dynamics of the Acacia Senegal Agroforestry System in the Sudan
… resulted in genetically different populations. Artificial selection of high yielding mother trees resulted in locating and identifying superior gum trees. They are recommended to be treated as seed stands for dissemination of high quality seed. Low gum producers yielded more biomass than high …
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Genetic constraints on the evolution of sexual size dimorphism
In this thesis, I use an artificial selection experiment and multivariate simulation modelling to study some basic questions concerning the evolution of sexual size dimorphism (SSD). Fecundity selection is often suggested as the main causal factor underlying the prevalence of female-biased SSD, but …
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Food intake in birds: hypothalamic mechanisms
… have been selected for egg production. Long-term selection has caused the LWS chicks to have different severities of anorexia while the HWS chicks become obese, thus making these lines a valuable model for metabolic disorders. Lastly, the Japanese quail have not undergone as extensive artificial …
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