Population size N
100
Initial frequency p₀
0.50
Selection coeff. s
0.00
Number of lineages
20
Fixed (A): 0
Lost: 0
Running: 0
Pred fix: 50%
Lost: 0
Running: 0
Pred fix: 50%
Fixation Probability
Neutral (s=0): P_fix = p₀ = 1/N for a single new allele
Beneficial (s>0): P_fix ≈ 2s (Haldane 1927)
Detrimental (s<0): P_fix ≈ 2s·e^(2s) → 0
Even a beneficial mutation usually goes extinct by drift. Only 2s fraction of mutations with s≈0.01 survive — just 2%.
Neutral (s=0): P_fix = p₀ = 1/N for a single new allele
Beneficial (s>0): P_fix ≈ 2s (Haldane 1927)
Detrimental (s<0): P_fix ≈ 2s·e^(2s) → 0
Even a beneficial mutation usually goes extinct by drift. Only 2s fraction of mutations with s≈0.01 survive — just 2%.