What are mutations and how do they contribute to genetic variation?

Mutations introduce new alleles into a population. An allele is a variant form of a gene. When a gene mutates, it creates a new version of that gene, which may result in a different protein or a different level of protein expression. This altered protein or expression can lead to a change in a phenotypic trait. For example, a mutation might change hair color, disease resistance, or metabolic efficiency. These new traits contribute to the genetic variation observed among individuals within the same species, providing the raw material for natural selection and evolution.