This hands-on activity supports concepts covered in the film Evolving Switches, Evolving Bodies about the evolution of stickleback fish. Students interpret molecular diagrams and build physical models of eukaryotic gene regulation.

Students review eukaryotic gene transcription using the example of a gene called Pitx1, which is involved in the development of pelvic spines in stickleback fish. They explore how changes in Pitx1 gene expression can affect body development, and learn how those changes, with the appropriate selective pressure, play a role in the evolution of a population. They will then create models showing how Pitx1 gene transcription is regulated in two morphologically different populations of stickleback fish.