Fig. 1.

PAQTL_6 contributed to petal-size reduction after the transition to selfing. (A) The evolution of the selfing species C. rubella through the breakdown of the self-incompatibility system found in C. grandiflora, has been followed by a strong reduction of flower size. (B) Flowers of NILgg and NILrr plants differing at the petal-size QTL PAQTL_6. (Scale bars in A and B, 5 mm.) (C and D) The average petal shape and size of C. grandiflora (Cg926), C. rubella (Cr1504), NILgg, and NILrr (C) and the quantification of petal area (D) indicate that PAQTL_6 contributed to reducing flower size after the transition to selfing. Values are mean ± SEM from 11, 12, 18, and 18 individuals, respectively. Letters indicate significant differences as determined by Tukey’s honest significant difference test. (E and F) EFD-PCA of petal outlines demonstrates that PAQTL_6 affects the overall petal dimension. Effects of variation in PC1 and PC2, which together explain more than 95% of the phenotypic variance, are shown in E. Distribution of individual petals projected on the PC1/PC2 morphospace is shown in F. Note that swapping the genotype at PAQTL_6 from the homozygote for C. grandiflora allele (NILgg) to the homozygote for C. rubella allele (NILrr) brings the petal geometry closer to C. rubella.