Genotype by environment interaction for survival and harvest body weight between recirculating tank system and pond culture in Penaeus monodon

Abstract

Genetic improvement of tiger prawn Penaeus monodon is challenging due to difficulties in breeding and rearing of this species in captive environments. To date, there have been very limited quantitative genetic studies in this species, especially genotype by environment (G × E) interaction between diverse farming systems (e.g., tank vs. pond). Therefore, the present study ran the long-term captive selection program for tiger prawn and obtained an in-depth pedigree of five generations (including base population and first generation) for genetic assessment of the environment impacts on two economically important traits in this species (i.e., survival and body weight at harvest). Originally, we evaluated the G × E interaction effect on survival and harvest weight between Biosecure Recirculating System (RAS) at the breeding nucleus and outdoor commercial ponds. Quantitative genetic analysis within mixed model methodology framework was carried out on 57,435 individual prawns (phenotype data from three latest generations, G2-G4) to examine possible effects of rearing environments on genetic parameters (heritability and correlations) for survival and body weight at harvest. The heritability (h2) for body weight was moderate (0.31–0.49) and differed slightly between the three testing environments. There were also significant heritable genetic variations of survival (h2 = 0.37–0.77) across the environments studied. The common full-sib effects accounted for 16 to 21% of total phenotypic variation for body weight and 11 to 18% for survival. Genetic correlations between body weight and survival were positive (0.23–0.46) in this population of tiger prawn. To examine the G × E interaction effect on survival and harvest body weight, the trait expressions in each environment were treated as separate traits and bi-variate models were used to estimate genetic correlations between homologous characters. An important finding of this study was that the between-environment genetic correlations for both body weight and survival were medium to high (0.56–0.70) between outdoor ponds; however, the estimates were low to moderate (0.17–0.31) between indoor RAS in the nucleus and outdoor ponds under field conditions. In summary, the moderate heritability for body weight and survival suggest that long-term response to selection can be achieved in this population of tiger prawn, and that the effects of rearing environments should be taken into consideration when conducting genetic improvement programs for this species, specifically the management of candidate parents to produce the next generation for selection.