Fig. 6

Stages of protein evolution after WGD. Immediately after duplication both paralogous copies undergo an initial phase of accelerated rate of evolution that affects the two gene copies in a similar manner (symmetric loss of evolutionary constraint), followed by a phase of deceleration in the rates of evolution (return to constraint). The degree of deceleration can be similar for both copies (symmetric return to constraint) or different between the paralogous copies (asymmetric return to constraint). Asterisks illustrate non-synonymous substitutions in the genes' sequences