This activity explores images of stickleback fish, some with spines and some without spines, which serve as phenomena for learning about gene regulation and natural selection.

Most stickleback fish in the ocean have structures called pelvic spines. However, stickleback fish in some lakes do not. The presence of pelvic spines is determined by a gene called Pitx1. For stickleback fish without pelvic spines, Pitx1 is not active in the pelvic area. The images show several modern-day and fossil stickleback specimens. The pelvic area is circled in each image.

The “Educator Materials” document includes background information and implementation suggestions for using the images as phenomena. The “Student Handout” includes the images and background information.

The “Resource Google Folder” link directs to a Google Drive folder of resource documents in the Google Docs format. Not all downloadable documents for the resource may be available in this format. The Google Drive folder is set as “View Only”; to save a copy of a document in this folder to your Google Drive, open that document, then select File → “Make a copy.” These documents can be copied, modified, and distributed online following the Terms of Use listed in the “Details” section below, including crediting BioInteractive.