MUTATION AND INBREEDING DEPRESSION
Inbreeding depression is the reduction in fitness (survival, growth, reproduction) in inbred organisms, compared to their non-inbred relatives. Inbreeding depression is the reason behind cultural and legal restrictions on mating of close relatives in humans, for example. We have shown that shellfish bear a large load of deleterious mutations that are the basis of substantial inbreeding depression. These genes appear to be responsible for the normally high mortality during the early life stages, a survivorship pattern known to ecologists as type-III. Only about one percent of fertilized oyster eggs reaches the juvenile stage.
Fixation, segregation and linkage of allozyme loci in inbred families of the Pacific oyster Crassostrea gigas (Thunberg):
McGoldrick, D. J., and D. Hedgecock. 1997. Fixation, segregation and linkage of allozyme loci in inbred families of the Pacific oyster Crassostrea gigas (Thunberg): Implications for the causes of inbreeding depression. Genetics 146:321-334.
Genetic inviability is a major driver of type III survivorship in experimental families of a highly fecund marine bivalve
Plough, L.V., G. Shin and D. Hedgecock. 2016. Genetic inviability is a major driver of type III survivorship in experimental families of a highly fecund marine bivalve. Molecular Ecology 25: 895-910.
High Genetic Load in the Pacific Oyster Crassostrea Gigas
Launey, S. and D. Hedgecock. 2001. High genetic load in the Pacific oyster Crassostrea gigas. Genetics 159:255-265.
Quantitative Trait Locus Analysis of stage-specific inbreeding depression in the Pacific oyster Crassostrea gigas
Plough, L. V., and D. Hedgecock. 2011. Genome-wide analysis of stage-specific inbreeding depression in the Pacific oyster Crassostrea gigas. Genetics 189:1-14.This paper, drawn from Louis Plough’s Ph.D. dissertation, provides dramatic documentation for a large number of highly deleterious mutations in the Pacific oyster. These mutations are expressed during the larval stages, particularly during metamorphosis, resulting in genotype-dependent mortality that amounts to ~96% of starting numbers (fertilized eggs). This research was supported by a grant from the NSF.