Selection maintains floral color polymorphism in scarlet paintbrush, <i>Castilleja coccinea</i> , reflecting combined ecological factors

Differences in floral color between morphs are consistent with diversification associated with a shift in ecological niche. We identified variation in edaphic and habitat conditions as probable drivers of divergence in floral color. Additionally, variation in other floral traits suggests a combined role of pollinators and habitat differences acting in concert to maintain distinct floral color morphs.