But what about these early-diverging, non-symbiotic leaf beetles? How do they get by? It turns out they encode their digestive enzymes endogenously. Just a fewer set of them compared to their symbiotic relatives. 6/n

This variance in metabolic potential relative to a symbiotic condition allowed us to then test the impact of symbiosis on the diversification and ecological breadth of leaf beetles. Symbiotic beetles turned out to be more speciose and exploit a greater variety of plants. 7/n