Avaliação de diferentes níveis de significância na identificação e caracterização de marcadores moleculares no melhoramento genômico

• Ano de defesa: 2007
• Autor(a) principal: Jangarelli, Marcelo
• Orientador(a): Euclydes, Ricardo Frederico
• Banca de defesa: Salaro, Ana Lúcia , Cecon, Paulo Roberto , Carneiro, Antônio Policarpo Souza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Melhoramento genético; Marcadores moleculares; Locos de caracteres quantitativos; Níveis de significância
• Palavras-chave em Inglês: Genetic improvement; Molecular markers; Quantitative traits locos; Significance levels
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS
• Link de acesso: http://locus.ufv.br/handle/123456789/4814

The genomic era came to transform science as a whole. The intention of this work was to evaluate different significance levels on the identification of the molecular markers, related with its quantitative characteristics of low, medium and high heritability (h²), aiming genetic improvement. A comparison between the significance levels of 1%, 5%, 10% and 20% was accomplished through a computer system of genetic simulation (Genesys), used for the simulation of three genomes, where each was constituted by only one low, medium or high h² characteristic, respectively. First from each of these genomes, was simulated a base population of 1000 animals (500 males and 500 females). Next, it was obtained an initial population for each one of the base population, totalizing three initial populations of 1000 animals each (10 males, 10 female/males and 10 son/female/males). After obtaining this population, was initiated the evaluation process of the four significance levels considered, using the selection assisted by markers (MAS), where the markers were identified by a linear regression analysis, admitting a minimum significance level for it. A total of four selection processes based on the initial population, according to the significance level adopted, was conducted through 20 consecutive generation, repeating each one 10 times to minimize the genetic oscillation effects. The analysis of the four significance level s differences was performed individually for each of the three characters, through a medium phenotype gain, looking forward to, besides checking the existence of gain distinction, if this difference will also appear simultaneously in the low, medium and high heritability characteristics. To complement and better explain the phenotype results obtained, other genetic parameters were considered, such as the endogamy coefficient, the number of markers used in the selection, the number of set alleles, the favorable and adverse allele setting and the selection s limit. The results obtained, indicated superiority in the significance level of higher magnitude ( 10% and 20%) related to the lower values ones (1% and 5%), and the phenotypic gains obtained after the assisted selection by the molecular marker, besides its benefits on the genetic parameter (lower endogamy coefficient; higher number of markers used, lower markers setting, lower percentage of adverse alleles set, and lower selection limits) for all three characteristics, although in an more expressive way for the low heritability character, and less for the high h². That way, even if the lower levels (1% and 5%) present a higher precision on the markers detection - QTLs ( quantitative trait loci), they are not satisfying enough related to the genetic benefits, resulting in a lower phenotypic and genotypic gain, making the choice of a certain statistic significance acceptable according to its aim and to the interdisciplinary research in question. It is notorious the relevance of statistics association on the identification of markers related to the QTLs and, consequently on the optimization of genomic improvement-programs.