2When is a population not evolving? How do we know if a gene pool has changed?The Hardy-Weinberg Principle can help answer these questions.
3The Hardy-Weinberg Principle states: Genetic equilibrium will be reached if the frequency of alleles remains stable generation after generation.Genetic equilibrium = no evolution occurring.
4Hardy-Weinberg Principle Conditions necessary for genetic equilibrium are:No mutation occursImmigration and emigration do not occur (population is isolated from other populations) - no gene flow.Population is very largeMating is totally randomAll individuals survive and reproduce equally (no natural selection)
5Hardy-Weinberg Principle It is virtually impossible to meet these conditions.Allelic frequencies do change in populations, therefore evolution occurs.The main application of this principle is calculating allele and genotype frequencies in a population.
6In a population, the sum frequency of alleles will equal 1. This can be expressed as:p + q = 1Where:p = frequency of the dominant alleleq = frequency of recessive allele
7Hardy-Weinberg Equation p2 + 2pq + q2 = 1Where:p2 = frequency of individuals homozygous for the dominant allele2pq = frequency of heterozygous individualsq2 = frequency of individuals homozygous for the recessive allele