Impacts of stocking on the genetic diversity of Colossoma macropomum in central Amazon, Brazil

Abstract

ABSTRACT. Tambaqui (Colossoma macropomum) is the main fish species farmed on a commercial scale in northern Brazil. In view of the current scenario of Brazilian aquaculture, studies on the genetic improvement and reproductive management of captive tambaqui are crucial in identifying the genetic variability of broodstocks and devising management practices. Genetic diversity of three tambaqui broodstocks in western Amazon was evaluated using molecular markers. Fin samples were collected from 89 fish; 38 from Balbina, 30 from a hatchery in Rio Preto da Eva, and 21 from the experimental farm of the Federal University of Amazonas (UFAM). Ten primers were used for the analysis of diversity and genetic structure. Of the 152 bands produced, 146 were polymorphic. The proportion of polymorphic loci showed little variation among the three stocks. The lowest and highest rates were found in the Rio Preto da Eva (80.92%) and Balbina (85.53%) stocks, respectively. Heterozygosity (H) and Shannon (I) indices were similar among the stocks; the lowest values were found in Balbina (H = 0.279 and I = 0.419), and the highest in UFAM (H = 0.294 and I = 0.439). Following analysis of the genetic structure and relationship, the sample was divided into two groups, with the Balbina stock clearly deviating from the others. The results suggest that, to increase genetic variability, molecular information may be used instead of replacement of wild breeders. The groups characterized here can be used in genetic improvement programs with other tambaqui broodstocks from different areas of South America.

Loss of genetic variability in the captive stocks of tambaqui,Colossoma macropomum(Cuvier, 1818), at breeding centres in Brazil, and their divergence from wild populations

“…While the production of C. macropomum is expanding, there are increasing concerns with regard to the maintenance of the genetic diversity of the farmed stocks, inbreeding depression, the potential of the farm stocks for the development of programs of genetic improvement, and the risk of intraspecific hybridization with wild populations. These problems have been aggravated by the history of domestication, the lack of any systematic breeding management, and the potential for interaction with wild populations in the Amazon basin, which makes the genetic improvement of existing stocks ever more necessary (Aguiar et al., ; Lopes et al., ; Queiroz, Sousa, Silva, & Inoue, ; Santos, Santana, Sá Leitão, Paula‐Silva, & Almeida‐Val, ).…”

“…This reflects a number of sampling problems, such as the regional focus of many studies, the use of markers with a poor resolution, and the inadequate or indirect sampling of the broodstocks through the analysis of the fry. In addition, the studies often overlook important aspects of the captive environment, such as reproductive patterns, the effective population size of the farmed stocks, the risks of inbreeding depression, the potential for genetic improvement based on the existing broodstock, the differences in comparison with natural populations, and the associated chances of hybridization with these populations (Aguiar et al., ; Calcagnotto & Toledo‐filho, ; Gomes et al., ; Jacometo et al., ; Lopera‐Barrero et al., ; Lopes et al., ; Queiroz et al., ; Ribeiro et al., ; Santos et al., ; dos Santos et al., ).…”

“…These problems have been aggravated by the history of domestication, the lack of any systematic breeding management, and the potential for interaction with wild populations in the Amazon basin, which makes the genetic improvement of existing stocks ever more necessary (Aguiar et al, 2013;Lopes et al, 2009;Queiroz, Sousa, Silva, & Inoue, 2016;Santos, Santana, S a Leitão, Paula-Silva, & Almeida-Val, 2016).…”

SHORT-COMMUNICATION Validation of reference genes for real-time quantitative PCR in tambaqui (Colossoma macropomum)

“…Total DNA and cDNA were used as templates for amplification. The DNA was extracted from tambaqui fin samples as described by de Queiroz et al (2016), and the cDNA was transcribed from total RNA isolated from the ovary. Cloning was performed in a pGEM-T Easy vector, and sequencing was performed in a 3500 Genetic Analyzer (Applied Byosystems ® ).…”

Genetic characterization of tambaqui stocks from two pisciculture stations in the lower São Francisco River

“…P. Aguiar et al, 2013;2018;N.M. Lopera-Barrero et al, 2015;Queiroz, Souza, da Silva, & Inoue, 2016;Ribeiro et al, 2016;Fazzi-Gomes et al, 2017). M. C. F. Santos et al (2007) and Fazzi- Gomes et al (2017) found high genetic variability in natural populations when compared to cultivated stock and little genetic differentiation and high gene flow between populations, indicating that these natural populations form a large panmictic population in the tributary system of the Amazon River.…”