I just found this fascinating tale of evolution in action. Researchers in 1971 placed a species of lizards on a small Croatian island where they did not previously exist. After 36 years of neglect due to war and polictical turmoil, scientists returned to the island. The native lizards to the island had been eliminated and the introduced lizards had changed from insectivores to herbivores. Their skulls had changed to eat leaves. Also, the lizards had evolved cecal valves, which are used to hold food in the digestive tract for digestion. Evolution can move very fast if conditions change.