Caracterização de corridas de homozigose, heterozigose e análise da diversidade genômica em populações bovinos

Abstract

The animal genome is characterized by long homozygous regions, in which identical haplotypes had been inherited over generations. The extension of each run of homozygosity is determined, in part, by the generations' number analyzed and the genetic relationship among animals evaluated. Still, long heterozygous regions can be observed, and it can be related to crossbreeding or associated with linkage disequilibrium. Therefore, it is understandable that one of the main aspects of genetic population studies is the verification of possible diversity among species, breeds, and cattle. Diversity becomes an important point of observation since the decrease in diversity can result in lesser selection results. With this, our main goal was to investigate the population structure of different bovine breeds, checking the existence of homozygous and heterozygous regions at bovine DNA and possible changes in genotype frequencies due to selection pressure, as well as comparing them to observe the genetic differences and/or resemblances. Thus, bovines of different breeds and purposes were be genotyped with different densities SNP panels, together with whole genome sequence, and the information acquired used to check the bovine autosomal DNA regions. These regions also were checked for selection signature, inbreeding, linkage disequilibrium, effective population size, besides genes identification that appears in regions with high homozygosity and heterozygosity. The characterization of a new bovine breed, developed in Southern Brazil for production in pasture-based systems (Purunã), which showed genomic similarity with the breeds used in the formation of the breed, but with particularities that do not allow a multi-breed evaluation. Besides, the characterization of the impact of different parameters on the evaluation of the heterozygous-enriched region, proves that different parameters regulated the detection of heterozygous-enriched regions. The results of this project make it possible to genetically characterize some of the main breeds of cattle, making it possible to deepen the genomic knowledge of the studied breeds, as well as results that may serve as a guide for future studies in the area of animal genetic diversity.