HETEROGENEOUS SELFING RATES AND DOMINANCE EFFECTS IN ESTIMATING HERITABILITIES FROM OPEN-POLLINATED PROGENY

Estimates of heritability from open-pollinated progeny trials were generally biased by heterogeneous selfing across families and by the presence of dominance, even when the intraclass correlation between sibs was adjusted for the average number of full- and half-sibs and for relatedness among the parents in the population. For high levels of selfing, with a constant selfing rate and inbreeding depression across families, dominance causes a downward bias in the heritabilities. Where rates of selfing and inbreeding depression varied, heritability was overestimated. However, except for low heritabilities, bias was of little practical importance, providing the correct coefficient of relationship among open-pollinated progeny was used.