Selection and evolution of flower colour

We currently know little about the evolution of flower colour when multiple pigment families are present. Ellis and Field examined the patterns of evolutionary transitions between anthocyanin-pigmented (red, pink, blue and purple) and yellow flowers in the tribe Antirrhineae.

Model for the pigmentation state space and possible transitions.
Model for the pigmentation state space and possible transitions. Combinations of alleles controlling anthocyanin and yellow pigments can give rise to four phenotypes. The transition rate from phenotype x to phenotype y across the phylogeny between two phenotypes is labelled qxy. Image by Ellis and Field (2016).

A phylogenetic comparative analysis points to selection for either yellow or anthocyanin pigmentation at different times. Nevertheless, these transitions are constrained to move through an unpigmented intermediate step. These findings suggest fluctuating selection favouring flowers with a single pigment over those with zero or two pigments.

Further reading

Tom J. Ellis, David L. Field, 2016, 'Repeated gains in yellow and anthocyanin pigmentation in flower colour transitions in the Antirrhineae', Annals of Botany, vol. 117, no. 7, pp. 1133-1140