Extreme diversification of floral volatiles within and among species ofLithophragma(Saxifragaceae)

Significance A major challenge in biology is to understand how complex traits important for ecological interactions between species coevolve and diversify across contrasting ecosystems. Floral scents are complex, and are often composed of a diverse array of chemicals important for interactions between plants and pollinators, herbivores, and microbial symbionts. We studied diversification of floral scents among populations of all woodland star species (Lithophragma ) across far-western North America. Floral scent variation was structured not only phylogenetically among species and geographically among populations, but some of the divergence was driven by local differences in the presence of coevolvedGreya moth pollinators. These results highlight the importance of conserving multiple populations of species if we are to maintain the evolutionary potential of coevolving interactions.