Evolution of Flower Color
Macroevolutionary trends in flower color across the angiosperms tend to be asymmetric, with most transitions involving a loss of flower pigments to yield white flowers, with only a few examples of color gains. Previous work from my phylogenetic analysis of Polemoniaceae and ancestral-state reconstructions highlight flower color shifts from a white-flowered ancestor to extant species with blue/purple, pink, or yellow corollas in both Linanthus and Leptosiphon. These two genera appear to be additional examples of the rare acquisition of color in flowers. Although the general transition from a plesiomorphous white flower to flowers with anthocyanins (pink, purple, blue) is clear, the specific transition points are uncertain because of several missing taxa in this part of the tree and poor resolution or support of species-level relationships in each genus. The pollination systems of many of these species are unknown, but several species have been observed to have bee, bee fly, or hawk moth pollinators. Whether or not flower color and pollinators are correlated is still unknown, with some studies supporting a correlation, while others show no such correlation and suggest that flower color evolves by other means, such as genetic drift or pleiotropic effects during selection on other genes.
For this project we used multiple accessions per species, including different color morphs that were collected in California Summer 2013. Using MYbaits probes for targeted gene capture and sequencing with an Illumina platform yielded 100 nuclear genes and close to the entire plastid genome. This provided insight into the evolution of flower color between species and the number of times flower color has changed.
Manuscript forthcoming.
Jacob B. Landis 