DOMINANCE VARIANCE - ASSOCIATIONS WITH SELECTION AND FITNESS

Strong directional, and to some degree stabilizing, selection usually erodes only additive genetic variance while not affecting dominance va riance. Consequently, traits closely associated with fitness should ex hibit high levels of dominance variance. In this study we compile a la rge number of estimates of dominance variance to determine if traits t hat are subject to strong selection and/or are closely associated with fitness have higher levels of dominance variance than traits less sub ject to selection pressure. Estimates were taken from the literature f or both wild and domestic species and each group was treated separatel y. Traits closely associated with fitness (life history) had significa ntly higher dominance components than did traits more distantly relate d to fitness (morphology) for wild species. No significant differences were found between life history and morphological traits for domestic species. Traits that were known to have been subject to intense direc tional selection (morphological traits for domestic species) had signi ficantly higher dominance estimates than did traits that were assumed not to have been subject to strong selection (morphological traits for wild outbred species). The results are discussed with respect to the maintenance of heritable variation and the bias introduced in the calc ulation of the full-sib heritability estimate by high levels of domina nce variance.