Selection Pressure

How selection strength shapes allele frequency change over generations

Generation: 0 Allele freq (p): 0.50 Mean fitness: 1.00
Δp = sp(1−p)[ph + (1−p)(1−h)] / w̄
With s = selection coefficient, h = dominance (0=recessive, 0.5=additive, 1=dominant). Mean fitness = p²·1 + 2p(1−p)·(1−hs) + (1−p)²·(1−s). Strong selection drives rapid fixation; weak selection lets drift dominate.