We have clarified this statement in the text. We refer to the nitrogen cost in the form of allocation to protein per pigment bound.
Introduction paragraph 2 – I am unsure we know that physbobilisomes require more resource than pcb proteins – this depends on the ratio of antenna to reaction centre? Please include references if R3 this has been shown. Also, not all Pcb proteins are constitutively expressed (e.g., see Bibby et al. Nature 2003).