Efeito da mutação em populações selecionadas utilizando simulação genômica

• Autor(a) principal: Martins, Marília Albuquerque de Sousa
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1301
• topic: Mutação; Seleção; Simulação; Mutation; Selection; Simulation; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS

This work aimed to study the effect of different mutation rates in populations subjected to individual selection, with different mating systems and intensities of feature selection in high and low heritability, using the following parameters: phenotypic values, inbreeding, fixation of favorable and unfavorable alleles and the selection limit, the long term. To enable the development of this study were simulated using the GENESYS program separately, twelve genomes consisting of a single trait that distinguishes itself by the value of heritability and mutation rate. Were simulated with two levels of heritability for the trait under study: high heritability (h2 = 0.60) and low heritability (h2 = 0.20) and three mutation rates: 1:10.000 = M1, M2 = 1: 100,000; M3 = 1:1,000,000. These mutation rates are expressed in terms of proportion of mutations / locus / generation, indicating the probability that 1 (one) out of 10,000, 100,000 or 1,000,000 simulated gene mutation will occur. From each simulated genome was initially obtained a base population consisting of 3,000 individuals with inbreeding rate equal to zero and equal proportion between males and females, all heterozygotes. From each simulated population-based randomly selected 10 males and 250 females. Through mating of individuals sampled, we obtained the initial populations, a total of twelve populations, having the following structures: a) six initial populations consisted of 1250 individuals representing a number of 5 descending for female, b) six initial populations with 500 individuals representing a number of 2 descending for female. Once formed the initial populations, began training for selected populations, a total of thirty-six, corresponding to two selection intensities (IS1 = Higher intensity of selection from; IS2 = Lowest intensity of selection), three mutation rates ( M1 = 1:10,000, 1:100,000 = M2, M3 = 1:1,000,000) and three mating systems (RAA = random mating; EIC = Deleting Brothers Complete; EICMI = Deleting Brothers Full and half-brothers) . The matings were performed between the players that had the best performances, which are chosen for parents of the next generation, based on individual selection. This method of selection was practiced for 20 consecutive generations and to minimize the effects of fluctuating gene, were performed 5 repetitions per generation. For populations with greater intensity of selection (IS1), in each generation were selected 10 males and 250 females and 5 offspring generated by mating a total of 1250 individuals, with equal proportion of males and females (625 males and 625 females), corresponding a selection intensity of 2.47 and 0.97 for males and females selected, respectively. As for populations with lower intensity of selection (IS2) were chosen the same number of males and females (10 and 250), respectively, generating only 2 offspring per breeding season, totaling 500 individuals, with equal proportion of males and females (250 males and 250 females) corresponding to a selection intensity of 2.16 for males. Populations had in common the same effective size of 38.46. It was observed that the gains achieved over the 20 generations of selection was higher for the higher rate of occurrence of mutations (1:10.000) for rates M2 (1:100,000) and M3 (1:1,000,000) for all mating systems (RAA, EIC and EICMI) and heritability (h2 = 0.60 and h2 = 0.20) in populations subject to greater selection intensity. However, higher mutation rate and higher intensity of selection resulted in an increase of inbreeding, higher fixation of unfavorable alleles and marked reduction in the selection limit. Systems that preclude mating between siblings provided lower coefficients of inbreeding. By linking these results with the heritabilities studied (0.20 and 0.60), all shown that the results were more significant for the character of high heritability.