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.

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.

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