Crossbreeding for Higher Yield and Resilience

One of the base technologies employed by Pacific Hybreed to improve the yield and resilience of shellfish is crossbreeding, a general scheme which aims to take advantage of the general and specific combining abilities of inbred parent lines to produce superior hybrid varieties.  Crossbreeding is commonly used to improve crops.  The first observation of hybrid vigor in corn was published in 1908; crossbreeding for hybrid vigor resulted in a 7-fold increase in the yield of corn in the United States since 1940.  We believe that similar progress could be made with shellfish.    

Bayesian Hierarchical Modeling of Yield in Incomplete Diallel Crosses of the Pacific Oyster Crassostrea Gigas.

Yin, X., and D. Hedgecock. 2019. Bayesian hierarchical modeling of yield in incomplete diallel crosses of the Pacific oyster Crassostrea gigas. Aquaculture 510:43-50.

The Pacific oyster shows dramatic hybrid vigor for yield and potential for rapid improvement through crossbreeding. Hybrid vigor is assessed by crossing inbred parent lines, acting as male and female parents, in all possible combinations; such a cross is called a “diallel.” Traditional statistical methods for analyzing diallel crosses are sensitive to missing information, which is common in practice. In this paper, part of the Ph.D. dissertation of Xiaoshen Yin, we use computer simulations to test the ability of a Bayesian hierarchical model to predict offspring and to rank parent lines. This model accurately predicts yield of offspring present in incomplete diallels and helps identify superior parent lines.

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Bivalve Genomics: Complications, Challenges, and Future Perspectives.

Curole, J. P., and D. Hedgecock. 2007. Chapter 29. Bivalve genomics: Complications, challenges, and future perspectives. In: Aquaculture Genome Technologies, Liu, Z. (editor), Blackwell Publishing, Ames, Iowa, pp. 525-543.

This book chapter reports progress in bivalve genomics, mainly with the Pacific oyster, in relation to genetic improvement.

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Heterosis for Yield and Crossbreeding of the Pacific Oyster Crassostrea Gigas

Hedgecock, D., and J. P. Davis. 2007. Heterosis for yield and crossbreeding of the Pacific oyster Crassostrea gigas. Aquaculture 272S1: S17–S29.

This paper provides major evidence for hybrid vigor in the Pacific oyster and lays the foundation for Pacific Hybreed’s crossbreeding program. Hybrid vigor is the dramatically greater yield, resilience, and uniformity in the offspring of a cross between two inbred parent lines.

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Hybrid Vigor in Pacific Oysters: An Experimental Approach Using Crosses Among Inbred Lines.

Hedgecock, D., D. J. McGoldrick, and B. L. Bayne. 1995. Hybrid vigor in Pacific oysters: An experimental approach using crosses among inbred lines. Aquaculture 137:285-298.

This study was the first experimental demonstration that crosses of inbred parent lines produced hybrid vigor for yield in the Pacific oyster. Yield or the amount of biomass produced per unit area or volume is a composite trait, reflecting both survival and growth. This paper follows Griffing (1990) in defining hybrid vigor as performance of hybrid offspring exceeding that of the better parent.

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