Answer :
The answer is: the "bottleneck effect" .
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The "bottleneck effect" is a type of "genetic drift" resulting from a "reduction in the population" such that the [surviving population] is "no longer genetically representative" [of the original population] .
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The "bottleneck effect" is a type of "genetic drift" resulting from a "reduction in the population" such that the [surviving population] is "no longer genetically representative" [of the original population] .
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