How does genetic variation and mutation play a role in natural selection?

Natural selection is a theory that states that those individuals who are best adapted to live in an area will survive and reproduce. Within a given population, there exists a normal degree of genetic variation that may or may not make an individual more adapted to the environment or, more importantly, changes in the environment. A species with a great deal of genetic variability is more likely to survive as a species in a changing environment than a species with limited variability.

Some mutations may be favorable for survival Ex. A genetic mutation can cause animals to be more resistant to illnesses.