Three-spine Stickleback's Ecological Impact (IMAGE) University of Pennsylvania Caption Threespine stickleback, which occupy lakes across the northern latitudes, are a tiny fish with an outsize impact on evolutionary research. A Penn biologist has found that a single gene affects the way they interact with their environment. Credit Seth Rudman Usage Restrictions In context of reporting License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.