BRAINCAKEGenetic Drift
Genetic drift is a change in allele frequencies in a population from one generation to the next that happens by chance, not because an allele gives any advantage.
It happens because not every individual reproduces, and each offspring receives a random half of its parents' alleles. By chance, some alleles are passed on more often than others, so their frequency rises, while others fall.
Genetic drift happens in all populations, but its effect is much greater in small populations. In a large population, random changes tend to cancel out. In a small population, a few chance events can change allele frequencies a lot.
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Key terms in this lesson
- genetic diversity
- The range of different alleles present in the gene pool of a population.
More in Gene Pools
- Different Sized Populations
- Isolation
- Selection Pressure
- Population Bottlenecks
- The Founder Effect
- Stabilising Selection
- Directional Selection
- Disruptive Selection
All 16 lessons in Gene Pools · All Edexcel A-level Biology topics