Fitness effect of <i>lacI</i> and <i>lacO1</i> mutations depend on genetic background.

<p>The fitness effect of <i>lacO1</i> and <i>lacI</i> mutations were measured in the ancestor and the G+L3-1 evolved genetic backgrounds when competed in the G+L environment. Gray points indicate fitness effect in competitions against the corresponding progenitor strains that do not have the added <i>lac</i> mutation; black points indicate fitness of <i>lacI</i> and <i>lacO1</i> mutations competed directly against each other. Lines connect competitions of the same type but in different genetic backgrounds.