Even using this example the dogs in this situation who able to adapt by whatever way to a corn diet, are selected in by Natural Selection. No one says that they asked for this gift. Usually a species is malleable to some extent and those who have the right genes or right abilities are selected in by Natural Selection because they are BETTER ADAPTED to take advantage of the resources found in the ENVIRONMENT.
My point is that it is the environment that determines which genes will survive, Without the environment of poverty, the tortilla gene would not be selected in.