Directional selection and changes in allele frequencies

For simple dominance and two alleles

genotype AA Aa aa

initial frequency p2 2pq q2

selection coefficient 0 0 s

relative fitness (w) 1-0 1-0 1-s

Formula to calculate change in f (A) (= p):

p = s p q2 (after 1 generation)

1 - s q2

40a-1