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

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