Significant Links Between Photosynthetic Capacity, Atmospheric CO2 and the Diversification of C3 Plants During the Last 80 Million Years.

Abstract

Changing CO2 concentrations will continue to affect plant growth with consequences for ecosystem functioning. The adaptive capacity of C3 photosynthesis to changing CO2 concentrations is, however, insufficiently investigated so far. Here, we focused on the phylogenetic dynamics of maximum carboxylation rate (Vcmax) and maximum electron transport rate (Jmax)-two key determinants of photosynthetic capacity in C3 plants-and their relation to deep-time dynamics in species diversification, speciation and atmospheric CO2 concentrations during the last 80 million years. We observed positive relationships between photosynthetic capacity and species diversification as well as speciation rates. We furthermore observed a shift in the relationships between photosynthetic capacity, evolutionary dynamics and prehistoric CO2 fluctuations about 30 million years ago. From this, we deduce strong links between photosynthetic capacity and evolutionary dynamics in C3 plants. We furthermore conclude that low CO2 environments in prehistory might have changed adaptive processes within the C3 photosynthetic pathway.