Random mating among genotypes

• Let us suppose that Mandelian population has the genotypes AA, Aa and aa in the frequency p² , 2pq and q²
• Since, the mating among genotypes are assumed to be random, the frequency of mating between male and female gametes will be product of frequencies of concerned genotypes in the population.

Genotype     AA    Aa    aa

Frequency   p²    2pq   q²

Frequency of AA progeny = p⁴ + 2p³q + p²q² = p²( p² + 2pq + q²) = p² [ (p+q)² = 1]

Frequency of Aa = 2p³q + 4p²q² + 2pq³ = 2pq ( p² + 2pq + q²) = 2pq

Frequency of aa = p²q² + 2pq³ + p ⁴ = q²(p² + 2pq + q² ) = q²