In bottleneck detection, what does a heterozygosity excess relative to expectation indicate?

In bottleneck detection, what does a heterozygosity excess relative to expectation indicate?

• A. Evidence for a recent bottleneck.
• B. Evidence for population expansion.
• C. Evidence for stable population size.
• D. Evidence for perpetual small population.

Answer: (D)

A recent bottleneck creates a temporary heterozygosity excess: after a sharp drop in population size, the number of alleles falls quickly, while heterozygosity declines more slowly. This means the observed heterozygosity can be higher than the level expected under mutation-drift equilibrium for the reduced allele set. It’s a transient signal that signals a recent bottleneck rather than long-term small size or population expansion. So the pattern points to a recent bottleneck rather than stable size, expansion, or perpetual smallness.

A recent bottleneck creates a temporary heterozygosity excess: after a sharp drop in population size, the number of alleles falls quickly, while heterozygosity declines more slowly. This means the observed heterozygosity can be higher than the level expected under mutation-drift equilibrium for the reduced allele set. It’s a transient signal that signals a recent bottleneck rather than long-term small size or population expansion. So the pattern points to a recent bottleneck rather than stable size, expansion, or perpetual smallness.