Variation in wild populations of Papaver dubium VI. Dominance relationships for genes controlling metrical characters

Abstract

Evidence is presented which suggests that genes controlling the juvenile characters leaf number and diameter and perhaps also elevation of the outermost leaf exhibit directional dominance, but that this dominance is probably very incomplete. The same probably holds for genes controlling flowering time. Dominance for these characters is in the direction which would be expected if plants with rapid development were at a selective advantage. The data on juvenile height are consistent with this idea. The fact that dominance seems to be incomplete, however, suggests that the optimum rate of development is not at the extreme of the range. This may be related to the observation that a considerable proportion of seeds germinate well before the growing season. Genes controlling the number of stigmatic rays exhibited very little potence, indicating that any selection on this character is of the stabilising type. Genes controlling capsule number, which is known to be an important component of fitness, show directional dominance for increased capsule number. The level of dominance in this case is probably high, since heterosis for this character was found in nearly all cases.