Effect of inbreeding on performance and genetic parameters of growth and survival traits in the Pacific oyster Crassostrea gigas at larval stage

The occurrence of inbreeding over generations cannot be avoided in breeding practice because of limited effective population sizes, and inbreeding is expected to decrease the heritability within populations. The Pacific oyster (Crassostrea gigas) is the most widely cultured shellfish species worldwide, however, the effects of inbreeding on the heritability of its economic traits remain unclear. In this study, the effect of inbreeding on the performance and heritability of growth and survival traits were investigated by an inbred line of the Pacific oyster. Two inbreeding groups, a low inbreeding group containing 25 F1 families and a high inbreeding group containing 25 F2 families, were constructed by this inbred line. The performance and heritability of shell height, shell length and survival traits of two inbreeding groups were compared with that of the wild group including 25 families at larval stage. The performance of growth and survival traits was affected negatively by inbreeding. Using the animal model, heritability was estimated for shell height, shell length and survival. Lower heritability in growth traits was observed in two inbreeding groups. However, for survival rate, the estimations of heritability were not influenced by inbreeding obviously. The medium heritability of larval survival rate (0.29-0.34) observed in the inbreeding groups indicates that their survival trait still has a good potential for selection. These results will helpful for the management of inbreeding in shellfish breeding programs.

Automated summary

Inbreeding in Pacific oysters was found to have negative effects on growth and survival traits, leading to lower heritability in growth traits but no significant impact on survival rate heritability. This suggests that there is potential for selection in survival traits in inbred populations, which could be valuable for shellfish breeding programs.