Founder effect vs. bottleneck effect
A small group of settlers founds an isolated community, and a rare allele carried by one settler becomes common there. This is:
Answer D: explanation for every choice
A
A bottleneck is a disaster drastically shrinking an existing population.
B
Gene flow is movement of alleles between populations through migration.
C
Nothing suggests the allele gives a fitness advantage. Its rise is due to chance.
D
Correct. A new population started by a few individuals carries only their alleles, by chance.
TakeawayFounder effect: a few individuals start a new population. Bottleneck: a disaster shrinks an existing one.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb58.