This animation shows how changes in the regulatory switch regions of a “paintbrush” gene lead to wing spot differences in Drosophila fruit flies.

The fly species Drosophila melanogaster and Drosophila biarmipes both have a “paintbrush” gene that controls pigmentation. As shown in the animation, only D. biarmipes also has a regulatory switch region that activates paintbrush gene expression in the wings. As a result, D. biarmipes has pigmented spots on its wings, and D. melanogaster does not.

This animation is a clip from a 2005 Holiday Lecture Series, Evolution: Constant Change and Common Threads. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different features.