PARENT SESSION
Monday, August 7, 8:00-11:30 am
COS 7 - Evolutionary ecology I
L-14, Lobby Level, Cook Convention Center
Presiders: K Mercer

Evolutionary responses to global climate change: how rising CO₂ concentrations influence natural selection on ecologically important plant traits.

Lau, Jennifer^*,1, Tiffin, Peter¹, Shaw, Ruth¹, Reich, Peter¹, ¹ University of Minnesota, St. Paul, MN

ABSTRACT- Rising atmospheric carbon dioxide (CO₂) concentrations have dramatic ecological effects on plant communities by influencing plant growth, nutrient composition, and morphology. Elevated CO₂ concentrations could also affect plant evolution by altering patterns of natural selection. Here we employ a large quantitative genetic experiment and FACE (Free Air Carbon dioxide Enrichment) technology to investigate how elevated CO₂ concentrations influence plant phenotypes and natural selection on them in the model plant Arabidopsis thaliana. We find that plants grown under elevated CO₂ are 17% taller, produce 43% more biomass, and 20% more fruits. They also produce more branches, thicker and bigger leaves, and experience reduced herbivory. Thus, CO₂ has strong impacts on plant phenotypes. With regard to evolutionary effects, we detect significant directional selection on 8 of 9 traits studied. For example, natural selection favors genotypes with more branches, increased biomass, and reduced specific leaf area. Despite this strong selection on most traits, elevated CO₂ does not detectably alter patterns of natural selection—the direction and magnitude of selection do not differ between ambient and elevated CO₂ environments. Furthermore, elevated CO₂ does not alter heritabilities or genetic correlations. Despite the fact that elevated CO₂ displaces plant phenotypes to a dramatic degree, we find no evidence of an evolutionary component to plant responses to rising CO₂ concentrations in this population.–

Key words: evolutionary ecology, global climate change, natural selection