Except that we have observed genetic variation arise from a population derived from a single organism. It is hardly an assumption. It is an observation.
You are observing the _expression_ of genetic information, you are not observing the genetic variation.
You have not mapped the genome of the original organism and then that of the adapted organism to show that there is added information in the genome of the adapted organism.
Observation equally supports the conclusion that the information necessary for the adaptation pre-existed in the original orgamism. Some populations are able to express it, others are not and therefore do not pass on this ability to express to their progeny. Natural selection at work.
Again, you are BLIND TO YOUR ASSUMPTIONS. Probably willfully so, because your assumptions justify something else.