The Hardy-Weinberg Principle By: Alex, Jared, Merrick and Larisa

What Is It? A principle that states in populations in which ONLY RANDOM CHANCE is at work, allele frequencies will remain constant generation to generation

The Hardy-Weinberg Equilibrium 1pp:2pq:1qq This is the EXPECTED GENOTYPIC RATIO

Example- Blue Eyes & Brown Eyes Say eye colour is inherited by dominance. B is the dominant allele for brown eyes and b is the recessive allele for blue eyes “p” is the frequency of the B allele “q” is the frequency of the b allele So, The genotype BB = pp The genotype bb = qq The genotype Bb = pq According to the Hardy-Weinberg principle, the expected allele frequencies of this population should be 1pp: 2pq : 1qq generation after generation For this example, this can also be written as 1BB: 2Bb: 1bb

So According To The Hardy-Weinberg Principle: The genotypic ratio of this population should remain 1BB:2Bb:1bb generation after generation But why isn’t this the case in nature?

BECAUSE Any factor that causes allele frequencies to change leads to evolutionary change, and the Hardy-Weinberg principle does not apply

Therefore, It Only Applies If: Mutation is not occurring Natural selection is not occurring The population is large (a smaller population increases chance of genetic drift) All members of the population breed All mating is totally random Everyone produces the same number of offspring There is no migration in or out of the population

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