Watch 123Movies. The rock pocket mouse is a living example of Darwin's process of natural selection. Evolution is happening right now everywhere around us, and adaptive changes can occur in a population with remarkable speed. This is essential if you're a mouse living in an environment where a volcanic eruption can reverse selective pressure in nearly an instant. The film features Dr. Michael Nachman, whose work on pocket mice reveals a complete story, from ecosystem to molecules, that demonstrates how random changes in the genome can take many paths to the same adaptation-a colored coat that hides them from predators.