Seleção genômica em populações simuladas

• Autor(a) principal: Santos, Lidiane Gomes dos
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1341
• topic: SNP; Densidade de marcadores; Intensidade de seleção; SNP; Density markers; Selection intensity; CNPQ::CIENCIAS BIOLOGICAS::GENETICA

The potential benefits of marker-assisted selection (MAS) in breeding have been widely discussed and some even discredited, since these associations, markertrait, explained very modest proportion of the total variation, with no significant impact on the improvement process. These combinations should be made to scale genomic assisted selection can effectively be realized, and this is what the selection is based on genomics. Thus, the genomic selection can be defined as the simultaneous selection for thousands of markers, which cover the entire genome of a dense so that all the genes should be in linkage disequilibrium with at least one of the markers. Methodologies for estimation of genomic breeding values (GBV) were first presented by Meuwissen et al. (2001), by means of a simulation study database. The simulation of populations has been used as a tool to geneticists for a long time to check the efficiency of new methodologies for the estimation of breeding values and comparison of selection methods. It was used in this study simulated data by GENESYS program. The basic structure of the genome was composed of 31 chromosomes total length of 200 1354cM quantitative loci (QTL) associated with the characteristic of the normal distribution. The genomes were differentiated by the distance between the molecular markers throughout the genome (1cm, 2cm and 4cm) and the value of the heritability of the trait (0.10, 0.30, 0, 60). The feature was defined with an average of 6.0 units and phenotypic standard deviation of 1.2 units. The selection was directed to increase the phenotypic value. The allelic mutation rate was 1:1,000,000, environment effects follow a normal distribution for simplicity we considered only the additive effects, disregarding any effect of dominance or epistasis and no fixed effects were analyzed. Comparisons were made in each heritability. Four studies were conducted within populations in genomic selection: i. Influence of the density of markers, ii. Influence of the number of escendants, iii. Influence of selection intensity, and iv. Influence of selection of females and mating directed. Despite high genetic gains and consequently high levels of phenotypic values were low inbreeding, since we have increases in genetic gain when we increase the intensity or when increasing the accuracy, as is the case of genomic selection. So, simply by improving the accuracy of selection we can find improvement in the average population. Thus the genomic selection would be an appropriate method to meet both short-term goals (increase and support ΔG), and the long-term (maintenance of genetic variance). As regards the selection of the limits, in general, there was a decrease in the total time that the population could respond to selection. The effective size, although a small difference appears to have influenced the determination of some parameters.