MUTATION-RATES AND DOMINANCE LEVELS OF GENES AFFECTING TOTAL FITNESS IN 2 ANGIOSPERM SPECIES

Theories about the evolution of sex and the effects of inbreeding depe nd on knowledge of the mutation rate and dominance level of deleteriou s alleles affecting total fitness. In two species of largely self-fert ilizing annual plants, minimal estimates of such mutation rates were f ound to be 0.24 to 0.87 per sporophyte genome per generation, but conf idence intervals exceeded 1.0 in each of the four populations. Dominan ce levels were near zero in one species and intermediate (0.28 to 0.35 ) in the other. These results suggest that the detrimental effects of inbreeding are a result of new partially recessive mutations rather th an overdominance.