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 “"additive genetic variance"”.
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Mechanisms Maintaining Additive Genetic Variance in Fitness in Red Squirrels
A trait must genetically correlate with fitness in order 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 …
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The use of microsatellites as a surrogate for quantitative trait variation in conservation
… biologists are interested in maintaining genetic variation in small populations, with a view to maintaining fitness and the ability of the species to adapt to changing environmental conditions. The most important type of genetic variation is therefore that which affects fitness and …
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Mapping quantitative trait loci using multiple linked markers via Residual Maximum Likelihood
… species is usually not feasible. Traditional genetic mapping methods, such as Least Squares and Maximum Likelihood, cannot fully accommodate complex pedigree structures, and more sophisticated methods such as Bayesian analysis are very demanding computationally. In this thesis, an alternative …
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Selection Response, Genetic Variation, and Combining Ability of High Oil Maize Genotypes
The second experiment was Genetic Variation in Alexho Elite High Oil Maize Synthetic Selected for Increased Grain Yield. The study showed significant genetic variability estimates were available for grain weight plant -1 in AEC6S3 lines and for grain yield in AEC6S2 x LH185 testcrosses. Due to …
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Estimation of Variance Components in Finite Polygenic Models and Complex Pedigrees
Various models of the genetic architecture of quantitative traits have been considered to provide the basis for increased genetic progress. The finite polygenic model (FPM), which contains a finite number of unlinked polygenic loci, is proposed as an improvement to the infinitesimal model (IM) for …
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Relationships Between Genetic and Ecological Variables in Nine Populations of Phlox Drummondii Hook (Niche, Allozymes, Genetic Differentiation)
… a correlation between niche breadth and level of genetic variation, was tested using nine populations of the annual plant, Phlox drummondii, from south central Texas. Niche breadth was measured as population response along controlled environmental gradients. Statistically significant differences …
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A Proposed Framework for Establishing Optimal Genetic Designs for Estimating Narrow-sense Heritability
… narrow-sense heritability with smallest possible variance, for a given amount of effort. We call this an optimal genetic design. The framework allows one to compare the variances of estimators of narrow-sense heritability, when estimated from each one of the alternative plans under consideration, …
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Efeito do cromossomo x no mapeamento de regiões genômicas sobre características de interesse econômico em búfalos da raça murrah
… windows that explained more than 0.5% of the additive genetic variance with 100 adjacent SNPs. Gene ontology analysis was exclusively conducted on significant windows of the X chromosome. Genes with potential functions in sexual precocity and reproductive efficiency emerged as candidates for …
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Estimation of genetic parameters in two maize recurrent selection programs
… of favorable alleles, while maintaining adequate genetic variability for continued selection. Iowa Stiff Stalk Synthetic (BSSS) is a maize population that has undergone continuous recurrent selection for more than 50 years as the base population for two independent selection programs (intra- and …
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Agronomic evaluation of four maize synthetics after recurrent selection for yield and evaluation of selected lines from the synthetics
… the yield of BSSS(R) and BS13(S(,2)); however, genetic drift may have caused significant yield reductions in BSCB1(R) and BS6(RS). BSSS(R) x BSCB1(R) and BS13(S(,2)) x BSCB1 (R) were improved similarly for yield indicating that both types of selection were equally effective for improving the …
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The genomics behind beauty: disentangling the complex coat color genetic architecture of gir breed
… (Ne) allow the characterization of population genetic structure, whereas genome-wide association studies (GWAS) enable the investigation of the genetic architecture underlying coat color. In this study, phenotypic records from 50,341 animals classified into 25 coat color categories were used, …
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Genotype by environment interaction for Holstein milk yield and fitness traits between Saudi Arabia and the United States
(Co)variance components and genetic parameters for Holstein first and all lactations mature equivalent milk and reproductive traits in the first four lactations were estimated by multiple-trait animal model using Method R procedures. The objectives of this study were to determine if genotype by …
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Lifetime fitness and changing life history traits in Red-cockaded Woodpeckers
… clutch size, age at first reproduction, and variance in clutch size affecting lifetime fitness. I also found that many traits were changing over time including lay date, clutch size, partial brood loss, and survival to year one. These traits were strongly influenced by local climate variables …
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Breeding Design for Atlantic Cod (Gadus morhua L.)
… Iceland. Throughout the rearing an estimation of genetic (co)variation of economically important traits and genotype by environment interactions (G×E) among the two rearing locations were explored. Atlantic cod in Iceland shows high additive genetic variance for body weight (h2 = 0.34), suggesting …
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Genomic selection studies in sheep using simulation and real data
… and genotype-by-environment modeling to improve genetic gains through sustainable breeding practices in sheep. It integrates a thorough review of sheep breeding programs in Turkey, a forward-looking simulation study of genomic selection in Akkaraman sheep, and an analysis of empirical data on …
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The contribution of non-additive and longitudinal genetic effects to health and cognitive traits
… yet understudied aspects of human trait genetic architectures: non-additive genetic effects and longitudinal genetic effects, with a focus on health and cognitive traits. Most genetic studies often focus on additive genetic effects estimated in unrelated individuals at single time points. …
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Mælidagalíkan fyrir íslenska kúastofninn
… utilize random regression (RR) models for genetic evaluation of dairy cows but in Iceland a lactation model is still used. The objective of this study was to investigate the genetics of lactation curves of Icelandic dairy cows and the possible benefits of implementing an RR model for …
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The Genetic Architecture of Juvenile Migration in Rainbow Trout (Oncorhynchus mykiss)
… life history, little is known of the underlying genetic architecture modulating this adaptive tactic. Using quantitative and molecular genetic techniques I describe the genetic basis of the marine migratory life history in three focused research chapters.</p> <p>In the first I conduct a …
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Genetic Heterogeneity of Residual Variance for Production and Functional Traits in American Angus Cattle
… around the mean. There is evidence that residual variance may be under genetic control, which opens the possibility of selecting for uniformity. In this sense, the objectives of the present dissertation were: 1) to investigate the extent of genetic heterogeneity of residual variance at the …
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Genomic Association Screening Methodology for High-Dimensional and Complex Data Structures: Detecting n-Order Interactions
… need to make restrictive assumptions about the genetic modes of inheritance. This thesis primarily focused on applying Model-Based Multifactor Dimensionality Reduction for quantitative traits, its performance and application to a variety of data problems. We carried out several simulation …
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