Format: ORAL

Matthew H. Koski

1. Department of Biological Sciences, Clemson University, Clemson, SC, USA

Floral coloration is nortoriously important for mediating plant-pollinator interactions though support for abiotic selection on floral pigmentation has increased over that last few decades. Pigments produced in the anthocyanin biosynthetic pathway both give rise to floral color diversity and are critical compounds for abiotic stress responses. As such, rapid abiotic shifts associated with global change have the potential to drive temporal change in flower coloration. I will discuss results from collections-based studies exploring whether flower color has changed over the last ~100 years across a diverse set of angiosperm taxa and whether such change is linked with abiotic factors such as temperature and ozone (a proxy for ultraviolet irradiance). I will then present data testing whether abiotic-induced flower color plasticity has the potential to contribute to responses of flower color to global change. Results show that taxa that have experienced stronger temporal changes in ozone and temperature have experienced greater change in floral pigmentation. The response to abiotic change depended on whether anthers are exposed to external environmental conditions or concealed by petal tissue, which is in line with petal pigmentations role in protecting pollen from abiotic stress. Plasticity studies revealed that UV exposure induced a pigmentaiton response in one focal species, but not in all populations. Thus, there is genetic variation for pigmentation plasticity. Temperature change induced a weaker pigmentation response that was not population-specific. Together, results show that floral pigmentation has responded to global change, and plasticity is one mechanism by which plants have elicited phenotypic responses. This change in pigmentaiton has the potential to impact plant-pollinator interactions, and plant reproductive output.