Mutation and sexual reproduction generate genetic variation, providing the raw material on which natural selection can act in evolving populations.
Coverage 2016–2023 · Updated 16 Jul 2026
Mutation creates new alleles by changing DNA sequence; sexual reproduction creates new combinations of existing alleles.
| Source | How variation is generated |
|---|---|
| Mutation | A new base sequence can create a new allele |
| Meiosis | Crossing over and independent assortment place existing alleles into new gamete combinations |
| Random fertilization | Combines one gamete from each parent into a new genotype |
In a sexually reproducing plant, a mutation may introduce a drought-tolerance allele; meiosis and fertilization then place that allele into varied genetic backgrounds.
Selection does not create a needed mutation. Mutations arise without regard to usefulness, and sexual reproduction reshuffles rather than invents alleles.
This objective is assessed through structured response, commonly using Explain / Identify / Outline.
Explain / Identify / Outline
Build the answer around this relationship: Mutation can create new alleles.
Representative question
Explain how sexual reproduction can eventually lead to evolution in offspring.
Core D4.1 examples follow the same causal route: heritable variation exists, a selection pressure acts, individuals differ in fitness, and alleles linked to higher reproduction become more common. Endler’s guppies and sexual selection are evidence versions of the same chain.
Core natural-selection exam answers should never stop at “the best adapted survive.” They need the chain: heritable variation exists, a named pressure acts, some individuals have higher fitness, and their alleles become more common over generations. Use this for abiotic pressure, overproduction, sexual selection, and Endler-style data.
