Evolution of coral pigments recreated.

In proteins homologous to the green fluorescent protein (GFP), formation of red fluorescence requires three autocatalytic steps, whereas only two are needed for green fluorescence. Multiple red/green color diversification events in the GFP superfamily may reflect convergent evolution of the more complex three-step pathway. In the great star coral Montastraea cavernosa, a recreated common ancestor of green and red proteins turned out to be green, indicating that in this case red proteins evolved their color independently from most other homologous red proteins. Furthermore, red color appears to have evolved gradually by small incremental transitions.