Figure 1.

Line cross means for fitness (=total number of seeds) for each of four line pairs (a, C1↔R1; b, C2↔R2; c, B1↔S1; d, B2↔S2) of Arabidopsis thaliana. C↔R=Castelnuevo, Italy and Rödåsen, Sweden; B↔S=Bolsena, Italy and Skuleberget, Sweden. In all cases, the P1 parent is from Italy and the P2 parent is from Sweden. Four cross types (F₁, rF1, F₂, rF₂) have an additive expectation halfway between the two parents; in some cases the points are obscured (see Supplementary Table S7 for values). F₁ and F₂ have P1 as the maternal parent, rF₁ and rF2 have P2 as the maternal parent. Half-filled circles represent means of the different F₁'s, the shading of the left half of the circle corresponds to the maternal parent. Error bars are 1 s.e., and in some cases are smaller than the size of the symbol. The dashed line is the expectation for purely additive gene action.