BRAINCAKEPopulation Bottlenecks
A population bottleneck is a large, sudden reduction in the size of a population, caused by an event such as a natural disaster, disease, habitat destruction or hunting.
The survivors are not chosen by natural selection for their alleles: which individuals survive is largely a matter of chance. The survivors carry only a small sample of the original gene pool, so:
- many alleles, especially rare ones, are lost completely;
- the allele frequencies in the survivors may be very different from those in the original population;
- genetic diversity is greatly reduced.
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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
- Non-Random Mating
- Different Sized Populations
- Isolation
- Selection Pressure
- The Founder Effect
- Stabilising Selection
- Directional Selection
- Disruptive Selection
All 16 lessons in Gene Pools · All Edexcel A-level Biology topics