Equations · Chemistry and biology
Hardy–Weinberg equilibrium
Genotype frequencies in a population that is not evolving, from the frequencies of two alleles.
p² + 2pq + q² = 1
Aethel says
p squared plus 2 p q plus q squared equals 1
What it says
If two versions of a gene have frequencies p and q, with p plus q equal to one, then under random mating the two kinds of homozygote occur with frequencies p squared and q squared and heterozygotes with 2pq.
Departures from these frequencies hint at selection, migration, mutation, drift or non-random mating.
Symbol by symbol
| Symbol | Say it | Means |
|---|---|---|
| p | p | the frequency of one allele |
| q | q | the frequency of the other allele |
| 2pq | 2 p q | the frequency of heterozygotes |
Where you meet it
Genetics and evolutionary biology.
Questions
How do you say Hardy–Weinberg equilibrium out loud?
p² + 2pq + q² = 1 is read: “p squared plus 2 p q plus q squared equals 1.” That is exactly what Aethel says when it meets the formula in a book.
What does p mean in Hardy–Weinberg equilibrium?
p (said “p”) is the frequency of one allele.
What does q mean in Hardy–Weinberg equilibrium?
q (said “q”) is the frequency of the other allele.
Can I listen to the equations in my own textbook like this?
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