Strong links between photosynthetic efficiency and the diversification of C3 plants during the last 120 million years

Changing CO 2 concentrations have and will continue to affect plant growth with consequences for ecosystem functioning. The adaptive capacity of C 3 photosynthesis to changes in atmospheric CO 2 concentrations is, however, insufficiently investigated so far. Here we focused on the phylogenetic dynamics of maximum carboxylation rate (V cmax ) and maximum electron transport rate (J max ) – two key determinants of photosynthetic efficiency in C 3 plants – and their relation to deep-time dynamics in species diversification, speciation and atmospheric CO 2 concentrations during the last 120 million years. We observed very strong positive relationships between photosynthetic efficiency and species diversification as well as speciation rates. V cmax as well as species speciation and diversification furthermore increased during periods of low prehistoric CO 2 concentrations. From our results we conclude strong links between photosynthetic efficiency and evolutionary dynamics in C 3 plants. We furthermore conclude, that increasing future CO 2 concentrations might rather hinder than facilitate evolutionary dynamics in C 3 plants.