Question

You are studying a group of Oregonian beavers, and you are interested in the population genetics of a single locus. You genotype 100 beavers and discover that for your locus of interest, there are 55 A¹A¹ homozygotes, 20 A¹A² heterozygotes, and 25 A²A² You estimate that the frequency of the A¹ allele is ["0.65", "0.35", "0.20"]         and that the expected number of A¹A² heterozygotes under Hardy-Weinberg equilibrium should be [ "12.25", "45.5", "50"]

choose number value for both blanks

Answer 1

Formulas for Hardy Weinberg Equilibrium -

?p^2 + 2pq + q^2 = 1 (genotypes)

?p + q = 1 (alleles)

?p = frequency of dominant allele

?q = frequency of recessive allele

?p^2 = genotypic frequency of homozygous dominant genotype

?2pq = genotypic frequency of heterozygotes

?q^2 = genotypic frequency of homozygous recessive genotype

?Genotypic frequency = # individuals with that genotype / # total individuals

?Frequency of allele = genotypic frequency of honozygotes with that allele + 1/2 genotypic frequency of heterozygotes

?Frequency of allele = √genotypic frequency

?Number of individuals with a particular genotype = total number of individuals x genotypic frequency of that genotype

Solution -

# total individuals = 55 + 25 + 20 = 100

A1 = 55/100 + 1/2 20/100 = 0.55 + 0.1 = 0.65

A2 = 25/100 + 1/2 20/100 = 0.25 + 0.1 = 0.35

Expected # of heterozygotes = A1A2 = 2 × 0.65 × 0.35 × 100 = 45.5

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