FIGURE 2.2 Phylogeny of the North American species of Aquilegia [see Whittall and Hodges (2007)]. Shading at the branch tips indicates flower color: black indicates blue; gray indicates red; and open indicates white or yellow. Taxa may be fixed for a flower color (whole circles at branch tips) or polymorphic (half circles at branch tips). Shading (as above) at nodes indicates the most parsimonious reconstruction of color, with the likelihood of producing anthocyanins indicated by shaded pie diagrams. To the right of taxon names are 3 boxes indicating, from left to right, the absence (open symbols) or production of delphinidins (black filled), cyanidins (hatched), and pelargonidins (gray) based on Taylor (1984). Arrows indicate down-regulation of genes late in the core anthocyanin pathway in flowers of that species compared with the regulation in the anthocyanin-producing species A. formosa, A canadensis, and A. coerulea (Whittall et al., 2006b). Lines on the right indicate species that form natural hybrids.