Principle # 1 : Genetic Variation Outside a rocky, dark mysterious cave are two different color mice. A variety of them are white and some are brown.
Principle #2 : Overproduction and Struggle for Survival A hungry fox comes out from the dark cave searching for food. He easily spots the white mice crawling outside of his cave.
Principle #3 : Differential Survival and Reproduction The brown mice were able to survive due to its environment and the mice's color.
Principle #4 : Changes in the Gene Pool Since the brown mice were able to survive, now they're able to pass on their traits and reproduce. This will make the population bigger and more mice can reproduce.