Total change of evolutionary theory.

[alien space marine]

Snow is white so animals slowly evolve to white who live in snow and their skin, hair etc all become suited for cold life. The desert is gold and brown so they become gold and brown, gaining skin and hair that help them in hot conditions. It's not entirely random and there has to be the catalyst of the environment to spark the change - otherwise the animal stays as it was and never has to change and evolve.

Polar bears turn slightly cinnamony when they are raised in a warm climate, Say the Arizona dessert.