I reallly like the example of corn because it contains all of the critical elements with a result that most anyone can understand. iirc the natural part of corn evolution was polyploidy followed by mutations in several of the duplicated genes. Then hoo-mons came along and further selected those genes further. I may have some elements wrong, as it has been many years since my evolutionary genetics class.
This is a great counter to the 'no new information' (or similar) argument. You have duplication of existing genes, then those genes mutate and the result is something brand new, an ear, a tassle, a soft seedcoat, etc that did not exist in the wild form.
Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"