English

Abstract

To elucidate the genetic mechanism of growth trait in Takifugu rubripes during ontogeny, developmental genetic analysis of body weight was conducted by mixed genetic model with additive-dominance effects, using complete diallel cross with three different strains of T. rubripes from Laizhou Shandong, Tangshan Hebei and Dalian Liaoning. Unconditional genetic analysis revealed that the unconditional dominance effects with very significant P<0.01 were detected during 8 to 20 months and the unconditional additive effects were detected only at 17 and 20 months. This suggests that the body weight trait was mainly controlled by dominance effects from 8 to 17 months and by both dominance and additive effects from 17 to 20 months. Conditional analysis showed that the net dominance effects were ascertained during growth from 0 to 8, 8 to 11, and 11 to 14 months, and the net additive effects were detected only during growth from 14 to 17 months. The following conclusions could be drawn from the results: the selection period should be considered during 14 to 17 months if the genetic improvement of T. rubripes is conducted using selective breeding, and the selection period should be considered during 8 to 14 months if cross breeding is used. The conditional genetic procedure is a useful method to elucidate the dynamics of genes action governing the variability of quantitative traits during ontogenetic development. In addition, the study is also highly important to determine the appropriate developmental period (t-1→t) for trait measurement in developmental quantitative genetic analysis in fish. Key words: Takifugu rubripes, body weight, genetic parameters, gene effects.