How do mutations provide the genetic variation needed for evolution by natural selection?

Mutation is the primary source of genetic variation, providing the essential raw material for evolution by natural selection.1

These alterations in an organism's genome occur randomly, often due to chemical errors during DNA replication or exposure to environmental factors like radiation. While most mutations are deleterious or silent, some result in new alleles that may offer a survival or reproductive advantage in specific environments.12

Natural selection acts as a filter for this variation:
* Preservation: If a mutation improves an organism's ability to survive and reproduce, the variant increases in frequency over generations because its carriers leave more descendants.2
* Elimination: Unfavourable mutations that reduce fitness are typically weeded out, as their carriers leave fewer or no descendants.2

By multiplying beneficial mutations and eliminating harmful ones, natural selection keeps the potentially disorganizing effects of random mutation in check, driving the adaptation and diversity of living organisms.2