![]() This study was conducted to estimate genetic parameters of growth traits in Pacific abalone to provide a database for selective breeding programs. It is important to carry out genetic improvement of economic traits for H. However, the rapid development of the aquaculture industry has caused problem of germplasm degeneration. Pacific abalone (Haliotis discus hannai) is one of the most valuable aquaculture species in China. Understanding genetic variation in larval biology is important for a comprehensive understanding of marine recruitment. This study demonstrates the feasibility of genotyping single larvae for the identification of multiple QTL. We found little overlap between vQTL and gQTL, suggesting that variation in these larval traits is controlled by different genes. Notably, shell-length variance among size classes maps to 6 major growth QTL (gQTL), with just 2 collectively explaining 18% of the variance. Consistent with previous work, 11 markers had genotypic frequencies that differed significantly from their Mendelian expectations and, upon mapping, are explained by 6 viability quantitative trait loci (vQTL). Parental tissues and a total of 144 larvae sampled from each size class were individually genotyped with a panel of 45 mapped DNA markers. We size-selected 1.42 million, 24 d old larvae to produce small, medium, and large size classes, constituting 93% of the population. Here, we reveal genetic variation in survival and growth of full-sib larvae of the Pacific oyster Crassostrea gigas reared under identical conditions. Environmental causes of differential larval growth and mortality are well studied, but genetic variation in these traits is less well understood. Variation in growth and survival of planktonic larvae has profound effects on marine population abundance. ![]() Overall, this study suggests that survival traits should be taken as improving target of next selection breeding programme in C. The genetic correlations between survival and growth traits at 140 days were low but positive (ranging from 0.23 to 0.27, respectively, between survival and SH and between survival and SL at 140 days after fertilization), suggesting that selection for survival may not have a negative response in growth. The genetic correlation between growth traits within age was medium to high and positive (ranging from 0.47 to 0.96, respectively, between shell length (SL) and shell height (SH) at 20 days and between SL and SH at 140 days after fertilization), suggesting that selection to improve single growth trait will cause positive response in another growth traits in C. The heritability of survival was low in larvae (0.13 ± 0.05 and 0.17 ± 0.04, respectively for 4 and 20 days after fertilization) but medium (0.39 ± 0.07) in spat, suggesting that selection for increasing spat survival was feasible. The heritability for growth traits in larvae and spat was 0.30–0.86 and 0.53–0.59, respectively, and varied with ages. ![]() Genetic parameters were estimated based on intraclass correlations of 49 full‐sib families (29 half‐sib families) in larvae (4 and 20 days after fertilization) and spat (140 days after fertilization) stages. gigas through genetic selection, the heritability and genetic correlations for growth and survival traits between different life stages were examined. In order to assess the feasibility of improving survival of C. The Pacific oyster Crassostrea gigas is a representative bivalve mollusc that is widely cultured in the world and is the largest molluscan group cultured in China. ![]()
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