Caracterização genética de reprodutores de tilápia : estratégias para a manutenção da variabilidade

Abstract

Tilapia native to Africa, are cultured worldwide. In the past 50 years, populations of Tilapia rendalli have been introduced in Brazil, afterwards Oreochromis niloticus and O. hornorum populations, originated from Ivory Coast, were also imported. In the last ten years, an O. niloticus strain named “Chitralada”, developed in Thailand, completely spread all over the country. One of the populations of O. niloticus named Nilotica that remained from the first imports is being cultured at the Aquaculture Station of Paulo Afonso, representing an unique genetic model. The objective of this study was to investigate the genetic variability and differentiation of two tilapia populations of O. niloticus and O. niloticus “Chitralada” reared in Paulo Afonso Station in order to verify the genetic potentiality of using niloticus population in the construction of a highly inbred strain for further QTL approach or in exploring hybrid vigor. Forty four individuals of each population were genotyped for three microsatellite markers and a total of 22 alleles were found. The mean heterozygosity detected was 0,471 for “Chitralada” population and 0 for the O. niloticus population. The coefficient of genetic differentiation (FST) was 0,627 and the mean inbreeding coefficient(FIS) was 0,309 for Chitralada population and was 1 for O. niloticus population. The absence of heterozygosity in the population of O. niloticus suggests that this population can be used in the development of a highly homozygous strain as well as in obtaining heterosis in crosses with “Chitralada” population.