It seems to me an example of this can be found in Douglas Futuyma lactose digestion experiment with bacteria, as described in Ken Miller's pointing out of how 'Irreducible complex' systems can evolve.
The experiemnt cuts one of the 3 genes needed for lactose digestion from bacteria, so you have a culture that can not digest lactose. After many generations and letting it grow to be billions, you feed it nothing but lactose, and some of those bacteria survive. They developed , through mutation, another set of 3 genes needed to digest lactose
http://www.millerandlevine.com/km/evol/DI/AcidTest.html
While talking about how Intelligent Design got it wrong, it also is an example where you have to have multiple traits develop at the same time to provide new function.