Genetic drift, population bottleneck, and allele fixation
Fixed: 0 | Lost: 0 | Segregating: 0
Wright-Fisher model: next generation drawn by binomial sampling. Neutral drift causes allele frequencies to wander.
A bottleneck (sudden population collapse) dramatically accelerates drift — most diversity is lost.
Fixation probability of an allele = its initial frequency p₀ (exact, regardless of N).
Mean time to fixation ≈ 4N generations. Bottleneck: acts like 2N_b generations of drift compressed into one event.