15. The system of claim 10 , further comprising: a fitness function selector configured for determining a metric associated with a user interface; and a fitness score calculator configured for calculating a score for each of the plurality of candidate user interfaces based on the inputs in accordance with the metric, wherein the one or more candidate user interfaces are selected from the plurality of candidate user interfaces based on their respective scores.
16. The system of claim 15 , wherein the metric is related to at least one of: revenue of a publisher associated with the identified user interface; and user experience of the plurality of users with respect to a user interface.