Answer:
When the mouse "eyeless" gene was implanted into the fruit flies it switches on the eye development.
Explanation:
The eyeless gene of mouse and fruit fly share a great homology. When Scientists took gene from Mouse and inserted it to fruit fly they observed that it initiated the development of eye at the same spot as the original fruit fly gene does. This implicated that the this gene is highly conserved and fruit fly and Mouse has evolved this gene from same ancestor.
