Genetic variability of wild and captivity populations of Colossoma macropomum (Cuvier, 1818)

Tambaqui (Colossoma macropomum) is among the most important fish species of the Amazon and one of the most cultivated in Brazil. In the present work we have evaluated the genetic variability of wild and captivity populations of C. macropomum. Enzymatic markers were used to estimate the genetic variability of 41 specimens from a wild group; and 30, 33 and 45 from three captivity groups, which came from Pentecostes (Ceara State), Jaboticabal (Sao Paulo State) and Itacoatiara (Amazonas State), respectively. Nine isoenzymic systems were used to evaluate the genetic variability of these populations. Using zimogram data we obtained the polymorphism level, allele number, allelic frequency, observed and expected heterozigosity, Wright F statistics (FIS FST), genetic distance, level of similarity and group analysis. The isoenzymic data showed that, from the nine systems, six presented polymorphic loci (Fbp-2, G6pdh-2, G6pdh-3, Pgi-1, Pgi-2 and Pgm-1). The populations from Pentecostes and Jaboticabal presented loss of genetic variability and low heterozigosity, compared to the wild population and to the artificial population acquired at Itacoatiara fish farm. Based on these results and on fish farmer information we could consider the population from Itacoatiara as recently derived from a wild population. Concluding, we suggest that the artificial populations of tambaqui, which contain animals originated from this funding population at Pentecostes, should be renewed with the introduction of a new group of individuals with genetic variability equivalent to the wild population. Keywords: conservational genetics, isozyme, fish management, tambaqui. O tambaqui e uma especie de peixe bastante importante na regiao amazonica e uma das especies mais cultivadas no Brasil. O objetivo deste trabalho foi avaliar a variabilidade genetica do Colossoma macropomum de cativeiro e selvagem, utilizando marcadores isoenzimaticos. Utilizamos 41 individuos de uma populacao da natureza e 30, 33 e 45 de populacoes de cativeiro de Pentecoste, Jaboticabal e Itacoatiara, respectivamente. Nove sistemas isoenzimaticos foram utilizados para verificar a variabilidade genetica do tambaqui, bem como os niveis de polimorfismos, numeros de alelos, frequencias alelicas, heterozigosidade observada e esperada, estatistica F de Wright (FIS e FST), distancia e similaridade genetica, e analise de agrupamento. Das nove isoenzimas analisadas apenas seis sistemas apresentaram polimorfismo (Fbp-2, G6pdh2, G6pdh