In the Hardy-Weinberg equation, what does 'p' represent?

In the Hardy-Weinberg equation, 'p' represents the frequency of the dominant allele in a population. The equation is a mathematical model used in population genetics to describe the genetic variation of a population at equilibrium.

When applying the Hardy-Weinberg principle, 'p' is the proportion of the dominant allele among all alleles at a particular locus. Conversely, 'q' represents the frequency of the recessive allele. The relationship between 'p' and 'q' is fundamental to understanding the genetic makeup of a population, as the sum of both frequencies equals one (p + q = 1).

This concept is critical for predicting genotype frequencies in a population under the assumption that it is not evolving, meaning there are no forces like mutation, selection, or drift acting on the population. By knowing the frequency of the dominant allele, one can derive the expected frequencies of homozygous dominant (p^2), heterozygous (2pq), and homozygous recessive (q^2) genotypes within that population.