Table 25.1

Situation	Allelic Frequencies	Genotypic Frequencies
Three alleles	f(A¹) = p	f(A¹A¹) = p²
	f(A²) = q	f(A¹A²) = 2pq
	f(A³) = r	f(A²A²) = q²
		f(A¹A³) = 2pr
		f(A²A³) = 2qr
		f(A³A³) = r²
X-linked alleles	f(x¹) = p	f(X¹X¹ female) = p²
	f(X²) = q	f(X¹X² female) = 2pq
		f(X²X² female) = q²
		f(X¹Y male) = p
		f(X²Y male) = q
Note: For X-linked female genotypes, the frequencies are the proportions among all females; for X-linked male genotypes, the frequencies are the proportions among all males.

Table 25.1: Extensions of the Hardy–Weinberg law