Foliar striping and floral traits are correlated with higher reproductive output in crimson monkeyflowers

Abstract

In plants, ecological interactions such as pollination depend on whole-plant phenotypes, where coordinated variation among vegetative, floral, and reproductive traits can shape reproductive success. However, empirical studies linking integrated phenotypes that include non-floral traits to reproductive outcomes within populations remain limited. While prior work has shown that crimson monkeyflowers exhibit heritable variation in foliar anthocyanin striping, the functional significance of the trait has been thus far unknown. Using plants derived from natural populations, we conducted field and greenhouse experiments to assess whether foliar striping is genetically correlated with traits related to pollinator attraction. We found that foliar striped plants consistently exhibit larger flowers, greater nectar rewards, and decreased proportions of viable pollen relative to non-striped plants. When we manipulated flowers within plants with and without foliar striping to allow only outcrossing or only self-fertilization in a field environment, we found that outcrossed flowers had higher reproductive success than did self-fertilized, with outcrossed flowers from plants with foliar striping producing the highest overall seed numbers and seed mass. Our results reveal patterns of coordinated foliar and floral trait variation and associated reproductive output that are consistent with a pollination syndrome framework. The link between foliar pigmentation and increased per-calyx reproductive output represents a novel association between foliar pigmentation and a broader evolutionary and ecological function.