Quantitative trait variation, phenotypic integration, and plasticity to elevated carbon dioxide in four recombinant inbred populations of Arabidopsis thaliana (Brassicaceae)

Abstract

Rapid changes in the concentration of atmospheric carbon dioxide, a key driver of global climate change, have been shown to affect ecologically important traits in plants. Characterizing the effects of novel genetic variation on quantitative variation, phenotypic integration (multivariate associations among traits), and plasticity to elevated carbon dioxide can shed light on short-term plant responses to climate change. Here we explored univariate and multivariate responses to elevated carbon dioxide among four recombinant inbred populations of Arabidopsis thaliana established from genetically divergent ecotypes crossed to a common genetic background. We found significant genetic variation in all traits, but no genetic variation in phenotypic plasticity (i.e., genotype by environment interactions) in any trait among recombinant inbred lines. Significant cross-environment correlation in fitness values showed similar patterns of selection between ambient and elevated carbon dioxide treatments. Our data suggest that outcrossing among A. thaliana ecotypes increases genetic variation in functional traits, but makes little or no contribution to genotype by environment interactions and patterns of phenotypic integration. However, multivariate analyses revealed shifts in patterns of phenotypic integration in response to elevated carbon dioxide. We conclude that multivariate plasticity will likely play an important role in shaping short-term responses to future carbon dioxide conditions in natural populations of A. thaliana.