Figure 1.

Petal lobe anthocyanin has been gained repeatedly in the luteus group of Mimulus. Closely related species outside the luteus group, like M. guttatus, are yellow‐flowered, with red anthocyanin pigmentation restricted to the nectar guide region of the corolla. Mimulus cupreus, M. l. luteus, and M. l. variegatus all produce a single type of anthocyanin pigment—cyanidin—which leads to floral colors ranging from orange to red to magenta depending on the relative intensities of cyanidin versus the yellow carotenoid pigments (Cooley, Carvallo, and Willis 2008). Mimulus cupreus and M. naiandinus have each gained petal lobe anthocyanin via a single locus change at genomic region pla1, which contains tandemly arrayed copies of candidate transcription factor genes MYB1, MYB2, and MYB3 (Cooley et al. 2011). The magenta‐petaled M. luteus var. variegatus gained petal lobe anthocyanin via a change at pla2, associated with an expansion in gene expression of the petal anthocyanin activator gene MYB5a (Zheng et al. 2021). A rare yellow‐flowered morph of M. cupreus, found in a single population in Chile, has lost petal lobe anthocyanin via a change at pla1 (Cooley and Willis 2009). Figure modified from Zheng et al. (2021). [Color figure can be viewed at wileyonlinelibrary.com]