C anatomy can evolve via a single developmental change.

C photosynthesis is a complex trait that boosts productivity in warm environments. Paradoxically, it evolved independently in numerous plant lineages, despite requiring specialised leaf anatomy. The anatomical modifications underlying C evolution have previously been evaluated through interspecific comparisons, which capture numerous changes besides those needed for C functionality.

Evolutionary implications of C3 -C4 intermediates in the grass Alloteropsis semialata.

C4 photosynthesis is a complex trait resulting from a series of anatomical and biochemical modifications to the ancestral C3 pathway. It is thought to evolve in a stepwise manner, creating intermediates with different combinations of C4 -like components. Determining the adaptive value of these components is key to understanding how C4 photosynthesis can gradually assemble through natural selection.