From the 2005 Holiday Lectures — Evolution: Constant Change and Common Threads

Stickleback Environment

At the end of the ice age, the retreating ice sheet created many new lakes, some of which were colonized by sticklebacks. The presence of different predators in different lakes dictated the subsequent evolution of each isolated lake stickleback over the course of about 10,000 years. Some groups kept their spines to use against predatory fish, such as trout. Others lost their spines, perhaps to evade aquatic insect predators.

1 minute 26 seconds
Play Large: MOV / WMV (9 MB)
Play Small: MOV / WMV (4 MB)

To download the videos, in Internet Explorer right-click the link and select "Save Target As..." In Firefox right-click and select "Save Link As..." In Safari right-click and select "Download Linked File As..."