The evolutionary ancestor of fruit flies had two pairs of wings. Modern fruit flies have one pair of wings and one pair of halteres, an organ involved in balance. A mutation in the modern fruit fly results in conversion of the halteres to wings. The mutant fly has two pairs of wings, so it resembles its evolutionary ancestor. What is the most likely reason the mutation converts one organ to another?
The program that commands the expression and development of an organ can be silenced by interruption of a molecular switch, for instance a blocking by a protein of a promoting region. This way it is possible to convert one organ initially silenced to a functional organ.
