population bottleneck

biology

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July 23, 2026

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A population bottleneck is a sharp reduction in the size of a population due to environmental events or human activities. This reduction can lead to a significant decrease in genetic variation within the population. When a population shrinks drastically, the surviving individuals may not represent the full genetic diversity of the original population. This can have lasting impacts on the species' evolution and survival, as reduced genetic variation can make populations more vulnerable to diseases or environmental changes. For example, the cheetah has very little genetic variation, likely due to past population bottlenecks.1

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evolution
Genetic drift
Such occasional reductions are called population bottlenecks. The populations may later recover their typical size, but the allelic frequencies may have been considerably altered and thereby affect the future evolution of the species. Bottlenecks are more likely in relatively large animals and plants than in smaller ones, because populations of…
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Such occasional reductions are called population bottlenecks. The populations may later recover their typical size, but the allelic frequencies may have been considerably altered and thereby affect the future evolution of the species. Bottlenecks are more likely in relatively large animals and plants than in smaller ones, because populations of…
Read More

Homo sapiens
Modern populations
…recently passed through a “bottleneck” in which the entire human population was reduced to a few hundred or perhaps a couple of thousand individuals, perhaps approximately 150 kya; however, this explanation is not universally accepted. Nevertheless, such a population size would be sufficiently small for a set of unique…
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…recently passed through a “bottleneck” in which the entire human population was reduced to a few hundred or perhaps a couple of thousand individuals, perhaps approximately 150 kya; however, this explanation is not universally accepted. Nevertheless, such a population size would be sufficiently small for a set of unique…
Read More