“…One possible explanation is that the full-red color of A. majus flowers was derived from an ancestor with very pale floral pigmentation, and all of the other palely pigmented members of the genus Antirrhinum might carry the same ancestral, low-activity ros allele. Investigation of this possibility would require a robust molecular phylogeny, which is not currently available for the European species, largely because the high degree of sequence similarity among species for the markers investigated to date makes resolution difficult, and also because there are significant levels of gene flow between sympatric populations as a result of the cross-fertility of the species (Oyama and Baum, 2004;Vargas et al, 2004;Mateu-Andres and de Paco, 2005;Venail, 2005). However, such an explanation of why color variation derives from variations in the activity of the MYB genes in the genus Antirrhinum is unlikely to be correct, because each species accession carries at least one distinct Ros allele, as judged by restriction fragment length polymorphisms with several different enzymes (Venail, 2005), and, although palely pigmented, the patterns of anthocyanin production in A.…”