Yes ,the ones that are beneficial, continue on ,they give an animal an advantage. The ones that are not, hinder the the animal,it ends up prey to predators ,so the mutation is stopped right away.
U THE MUTATION
IM THE REAL HUMAN
HOW CAN A THOUSAND MILLON BOOKS BE WRONG LOL
Not always...but it can. Often its a change you wont see, or something like eye color... But there is a lot of genetic mutations in nature, especially in animal colonies that are shut off from any other colony of the same species. So i guess there is not really one answer on your question till you go further into detail...sowwy