Summary
Predicts that allele and genotype frequencies stay constant in an idealised population, following p squared plus 2pq plus q squared.
In depth
Under no selection, mutation, migration, drift or nonrandom mating, allele frequencies (p + q = 1) and genotype frequencies (p² + 2pq + q² = 1) remain constant. Deviations indicate evolution is occurring.
It is used to estimate carrier frequencies: if 1 in 2500 are affected by a recessive disease, q² = 0.0004, q = 0.02, and carriers 2pq are about 4 percent.
Common mistake: the principle describes genotype frequencies, not individuals' traits.
Frequently asked questions
What is Hardy-Weinberg Principle?
Predicts that allele and genotype frequencies stay constant in an idealised population, following p squared plus 2pq plus q squared.
Which area of biology covers Hardy-Weinberg Principle, and how advanced is it?
Hardy-Weinberg Principle is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Homozygous and Heterozygous, Heritability, Sex-Linked Inheritance.
What should I learn before Hardy-Weinberg Principle?
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Hardy-Weinberg Principle. Intermediate topics assume the Beginner vocabulary.
What topics are related to Hardy-Weinberg Principle?
The closest topics to Hardy-Weinberg Principle are Homozygous and Heterozygous, Heritability, Sex-Linked Inheritance, Population Genetics Models. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Hardy-Weinberg Principle?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Hardy-Weinberg Principle. To practise the whole of Genetics, use the Genetics quiz.
How is Hardy-Weinberg Principle different from Homozygous and Heterozygous?
Hardy-Weinberg Principle: Predicts that allele and genotype frequencies stay constant in an idealised population, following p squared plus 2pq plus q squared. Homozygous and Heterozygous: Homozygous means two identical alleles for a gene; heterozygous means two different alleles. Read both side by side and note what each one explains.
What is a common mistake about Hardy-Weinberg Principle?
The principle describes genotype frequencies, not individuals' traits.
How should I study Hardy-Weinberg Principle step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Homozygous and Heterozygous and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.