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How do mutations create variation in populations?
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A herd of African elephants (Loxodonta africana) drinking from the Chobe River, Botswana.
Mutation is the ultimate source of all hereditary variation within populations, serving as the raw material for evolution by natural selection.21
Mutations create variation by introducing new mutant alleles into a population's gene pool. This process occurs through several mechanisms:
- DNA Alterations: Mutations arise from random changes in DNA sequences, such as point mutations (base-pair substitutions) or frameshift mutations caused by insertions or deletions.23
- Chromosomal Changes: Larger-scale chromosomal mutations—including deletions, duplications, inversions, and translocations—can alter the structure and function of entire DNA molecules.2
- Mutational Pressure: As mutations occur over generations, they accumulate in a population. This "dripping faucet" of genetic change, combined with natural selection and chance, determines the frequency of specific alleles.21
While many mutations are deleterious or silent, some provide beneficial traits that may increase in frequency within a population over time, driving biological diversity.2