Stickleback Practice Test

The main idea here is that sticklebacks are a powerful model for rapid adaptation because they show repeated, predictable evolutionary changes in many independent populations within a short time frame. This parallel evolution occurs when freshwater sticklebacks repeatedly evolve similar traits—like reduced armor plates and pelvic girdles—despite starting from related marine populations. The consistency of these changes across different populations reveals natural selection acting under similar ecological pressures, making it possible to study both the phenotypic shifts and their genetic underpinnings, often in just a few generations. In this system, researchers can link quick changes in visible traits to specific genetic changes, explore how different populations converge on the same solutions, and compare how similar environments drive similar outcomes. The fact that these evolutions happen repeatedly and quickly, across many independent populations, makes sticklebacks an especially informative model for understanding evolution in action. The other statements don’t fit because the genome is not simply trivial to analyze, sticklebacks do respond to selection (they are classic examples of rapid adaptive change), and they are not restricted to laboratories—they are found in wild freshwater and marine environments worldwide.