2020 ESA Annual Meeting (August 3 - 6)

COS 219 Abstract - The response of floral pigmentation to 70 years of global change in ozone and temperature

Matthew Koski, Biological Sciences, Clemson University, Clemson, SC, Tia-Lynn Ashman, Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA and Drew MacQueen, Scholar's Lab, University of Virginia, Charlottesville, VA
Background/Question/Methods

Elevated pigmentation ameliorates stress caused by UV-B exposure in both plants and animals. During the 20th century rapid declines in ozone resulted in elevated UV incidence in terrestrial and aquatic habitats. Elevated UV irradiance has been shown to favor larger areas of UV-absorption on the petals of flowers, which can protect pollen from UV damage. We used >1200 herbarium specimens from ~1950 to present to link UV floral pigmentation with historical ozone and temperature in 42 species spanning three continents to answer the following questions: 1) has the area of petals pigmented with UV-absorbing compounds increased over time? 2) is elevated pigmentation linked with reduced ozone (higher UV) when controlling for temperature? and 3) Do taxa experiencing larger declines in ozone experience larger increases in pigmentation? In all cases, we predict that species with exposed anthers will be more sensitive to ozone fluctuations than those with anthers protected from UV, i.e., enclosed within petals.

Results/Conclusions

Overall there was a modest positive effect of year on the area of UV pigmentation, but temporal change was highly species specific—increasing in some taxa but decreasing in others, and depending on continental distribution. Both ozone and temperature tended to have negative effects on pigmentation. That is, elevated floral pigmentation was associated with lower ozone and lower temperature. As predicted, species experiencing larger temporal declines in ozone displayed more dramatic increases in pigmentation. Pigmentation, however, declined in species with protected anthers that experienced more extreme increases in temperature over time. Results support the idea that recent anthropogenic global change in both ozone and temperature has elicited rapid phenotypic responses in floral pigmentation in some species.