RuBisCO adaptation is more limited by phylogenetic constraint than by catalytic trade-off

RuBisCO assimilates CO2 to form the sugars that fuel life on earth. Correlations between RuBisCO kinetic traits across species have led to the proposition that RuBisCO adaptation is constrained by catalytic trade-offs. However, these correlations were founded on the assumption that kinetic measurements in different species are independent. Here, we show that this assumption is incorrect in angiosperms by evaluating the dependence of variation in RuBisCO kinetic traits on the phylogenetic tree that relates the enzymes. We show that there is significant phylogenetic signal in all carboxylase kinetic traits in angiosperms, and significant phylogenetic signal in the Michaelis constant for O2 in species that conduct C3 photosynthesis. When accounting for this non-independence, we show that the catalytic trade-off between carboxylase turnover and the Michaelis constant for CO2 is weak (~30 % dependency) and that the correlations between all other RuBisCO kinetic traits are either not-significant or marginal (