What does "p2" represent in the Hardy-Weinberg equation?

In the Hardy-Weinberg equation, "p²" represents the frequency of the homozygous dominant genotype in a population. This means that it indicates the proportion of individuals who carry two dominant alleles for a particular trait, which is denoted as "RR" in genetic notation.

In the context of the Hardy-Weinberg principle, "p" represents the frequency of the dominant allele (R), so when "p" is squared (p²), it reflects the frequency of individuals in the population that are homozygous for this dominant allele. The equation as a whole, p² + 2pq + q² = 1, describes the expected genetic variation and proportions of genotypes (homozygous dominant, heterozygous, and homozygous recessive) in a large, randomly-mating population that is not evolving.

Understanding that "p²" specifically targets those individuals with the two copies of the dominant allele is crucial for interpreting genetic data within populations and applying the Hardy-Weinberg principle correctly.