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.