A population of 50 diploid individuals undergoes a severe bottleneck for 3 consecutive generations with no mutation, migration, or selection. The initial heterozygosity is $H_0=0.55$. Calculate the expected heterozygosity after the bottleneck and the probability that allele $A$ (initial frequency $p=0.4$) becomes fixed.

Step-by-step solution

1. Compute drift factor: $1-\frac{1}{2N_e}=1-\frac{1}{100}=0.99$.
2. Raise to the power of 3 generations: $(0.99{)}^{3}approx0.9703$.
3. Multiply by initial heterozygosity: $0.55\times 0.9703\approx 0.534$ (expected $H$ after bottleneck).
4. Under neutral drift, probability of fixation equals initial allele frequency: $p=0.4$.

Concept tested: Genetic drift and bottleneck effects

Published 28 September 2026 · How this solution was prepared and checked