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Title: Isolamento, caracterização de locos microssatélites e estimativa da variabilidade genética de Brycon amazonicus (Spix & Agassiz, 1829) (Characidae: Bryconinae) em ambiente natural e cativeiro
Authors: Araujo , Gisele Torres Clímaco de
metadata.dc.contributor.advisor: Val, Vera Maria Fonseca de Almeida e
Keywords: Matrinxã
Brycon amazonicus
Issue Date: 8-Aug-2012
Publisher: Instituto Nacional de Pesquisa da Amazônia - INPA
metadata.dc.publisher.program: Genética, Conservação e Biologia Evolutiva - GCBEv
metadata.dc.description.resumo: Fisheries and aquaculture are important economic activities in the Amazon region, both for subsistence and for commercial purposes. Among the native species in aquaculture farm, matrinxã (Brycon amazonicus) stands out for its good weight gain and good growth rate in captivity, and its acceptance for commercial food, getting good results on induced spawning. However its genetic profile in the wild and captivity is still unknow. Particularly when you consider that genetic variability is an important parameter to ensure the survival of a species before some environmental disturbance it is important to measure genetic variability. A tool to verify the genetic diversity of prokaryotes and eukaryotes is the microsatellite marker, because these markers are highly polymorphic in nature, multiallelic, present Mendelian inheritance, and are easily detected by PCR (Polymerase Chain Reaction). Therefore, the main goal of this study was to assess the genetic variability three populations of matrinxã: two from fish farms and one from a natural environment, with the aim of for conservation of genetic resources of this specie. For this purpose, 31 loci were isolated by constructing a genomic library enriched microsatellite according to the methodology Billote (1999). The characterization was performed using 32 individuals from nature (the wild population - Lake Catalan, Manaus, Amazonas). As a result, we obtained 16 polymorphic loci that were used to verify the existence of structuring among populations of this study. Statistical analyzes revealed that there is a lack of heterozygotes (f > 0) in all populations studied. It was also observed that there is a genetic differentiation (FST = 0.169; RST = 0.129). Molecular Analysis of Variance showed that populations are differentiated, i.e., with a tendency to become distinct groups. In addition, there was a correlation between genetic distance (Nei, 1972) and genetic identity, revealing that populations of Balbina and Rio Preto da Eva possibly originated from a common population, and over time began to divergent genetically from wild specimens. This result can be confirmed by the UPGMA dendrogram obtained using genetic distance with 100,000 bootstraps, which was observed in two separate groups: the first has two captive populations in the same clade, while the population is isolated from nature in another group. A Bayesian analysis was performed using the software Structure (Pritchard et al., 2000) with a model that allows mixing of populations. The results revealed that the populations are genetically structured in three distinct groups, ie, populations of Rio Preto da Eva, Balbina and Catalão. Five polymorphic microsatellite loci were sufficient to determine the relationship between parents and offspring in the population from Rio Preto da Eva. This measurent may cooperate with the programs of selective breeding. The structure observed in the studied populations indicates that a new rotation of parents must be done on fish farms, in order to increase the production levels. In relation to the wild population, overfishing may be contributed to the low genetic variability, but further studies in other populations along the Rio Negro are required to obtain a better genetic profile for this species in the nature.
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