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

Changing CO concentrations will continue to affect plant growth with consequences for ecosystem functioning. The adaptive capacity of C photosynthesis to changing 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 capacity in C plants-and their relation to deep-time dynamics in species diversification, speciation and atmospheric CO 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 CO fluctuations about 30 million years ago. From this, we deduce strong links between photosynthetic capacity and evolutionary dynamics in C plants. We furthermore conclude that low CO environments in prehistory might have changed adaptive processes within the C photosynthetic pathway.