Climate has the potential to influence evolution of organisms. One way to approach this topic would be to measure how natural selection changes over long periods that vary in environmental conditions. Dr. Diane Campbell, Professor of Ecology and Evolutionary Biology, recently published results of measuring selection over a uniquely long time period for plants. She quantified the strength of selection on floral traits of a subalpine plant in the Colorado Rockies each year for 10 years that differed in precipitation, causing extreme variation in the date of snowmelt. Selection for longer flowers was stronger in the years with later snowmelt, as more water can allow the higher pollinator visitation by hummingbirds and hawkmoths to yield higher seed production. Selection on flower width also varied across years, favoring narrower flowers in two unusual years with abundant hawkmoths, and wider flowers in another late snowmelt year.
The results illustrate how climate change could alter natural selection even when the primary selective agent is not directly influenced. The work appeared May 13 in Proceedings of the Royal Society B. It was co-authored with John Powers, an undergraduate who worked with Professor Campbell during the summer at the Rocky Mountain Biological Laboratory field station and who will be coming to UCI as a PhD student with Professors Sakai and Weller in Ecology and Evolutionary Biology.