Principle 1: Genetic Variation There are 2 types of mice, light mice and dark mice. These mice are usually located near the entrance of the cave.
Principle 2: Overproduction/Struggle for Survival Mice can have up to 10 mice in one litter. However, it's a struggle as predators, such as foxes. Because of this, not all of the mice live to adulthood as some are eaten due to the color of their fur.
Principle 3: Differences in Survival and Reproduction Since more of the light colored mice are being eaten, predators will most likely miss the dark colored mice and leave. This means that the dark colored mice will live to reproduce offspring.
Principle 4: Changes in Gene Pool As more dark mice reproduce, that trait will be increased within the population and the trait for light colored mice will decrease for generations to come.