Population genetics; the Hardy-Weinberg principle

Population genetics; the Hardy-Weinberg principle

1. Gene pool; is the sum of all the alleles in a population. The members of each population, therefore have the same gene pool.

2. Allele frequency; refers to the population or percentage of a particular allele of a gene in a population, relative to other alleles of the same gene.

3. The Hardy-Weinberg equation; is an equation to calculate allele and genotype frequencies within a population

4. p = represents the frequency of the dominant allele, q = represents the frequency of the recessive allele, p + q =1.0

5. However in diploid organisms alleles occur in pairs. In order to calculate genotype frequency rather than allele frequency, a second equation is used; p2 + 2pq + q2 = 1.0

   • where; p2 = frequency of the AA genotype, 2pq = frequency of the Aa genotype, q2 = frequency of aa genotype

6. The Hardy-Weinberg priciple; the frequency of dominant and recessive alleles in a popuation will remain constant from generation to generation provided certain conditions are met, these are;

   • 1. The population is large
     • 2. Mating is random
       • 3. No mutations occur
         • 4. There is no immigration into or emmigration out of the population
           • 5. All genotypes are equally fertile so that no natural selection is taking place

7. The name given to a change in allele frequency due to change is called genetic drift