Concept explainers
Assume that you are sampling a trait in animal populations; the trait is controlled by a single allelic pair A and a, and you can distinguish all three
Calculate the distribution of phenotypes in each population as expected under Hardy-Weinberg equilibrium. Is population I in equilibrium? Is population II in equilibrium?
To determine: Whether Population I is in Hardy-Weinberg equilibrium.
Introduction: A population is in Hardy-Weinberg equilibrium where the allele and genotype frequencies remain constant over generations. Hardy-Weinberg equilibrium follows the given equation, p2 + 2pq + q2 = 1, where, p2 represents the dominant homozygous genotype, q2 represents the recessive homozygous genotype and 2pq represent the heterozygous genotype.
Explanation of Solution
The animal population has A is a dominant allele and a is a recessive allele.
Genotype | Number of individuals | Frequency |
AA | 300 | 300/1000=0.30 |
Aa | 500 | 500/1000=0.50 |
aa | 200 | 200/1000=0.20 |
Total | 1000 |
Frequency of allele A
For a population in Hardy-Weinberg equilibrium
In this case
Putting the values in the above equation,
Distribution of population according to Hardy-Weinberg equilibrium is as follows:
Genotype | The phenotypic ratio at Hardy-Weinberg equilibrium | Number of individuals (ratio x total number of the individual) |
AA | 0.30 | 300 |
Aa | 0.50 | 500 |
aa | 0.20 | 200 |
Total | 1 | 1000 |
Population I is at Hardy-Weinberg equilibrium as expected and the observed phenotype is the same.
To determine: Whether Population II is in Hardy-Weinberg equilibrium.
Explanation of Solution
The animal population has A is a dominant allele and a is a recessive allele.
Genotype | Number of individuals | Frequency |
AA | 400 | 400/1000=0.40 |
Aa | 400 | 400/1000=0.40 |
aa | 200 | 200/1000=0.20 |
Total | 1000 |
Frequency of allele A
Frequency of allele a
For a population in Hardy-Weinberg equilibrium
In this case
Putting the values in the above equation,
Distribution of population according to Hardy-Weinberg equilibrium is as follows:
Genotype | The phenotypic ratio at Hardy-Weinberg equilibrium | Number of individuals (ratio x total number of an individual) |
AA | 0.36 | 160 |
Aa | 0.48 | 480 |
aa | 0.16 | 160 |
Total | 1 | 1000 |
Population II is not at Hardy-Weinberg equilibrium as expected and the observed phenotype is not the same.
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