Evolution is one of the unifying themes of biology. Evolution involves change in

Question

Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (a) What is the frequency of each genotype (AA, Aa, aa) in this population? What is the frequency of the dominant phenotype? (b) How can the Hardy-Weinberg principle of genetic equilibrium be used to determine whether this population is evolving? (c) Identify a particular environmental change and describe how it might alter allelic frequencies in this population.

Explanation / Answer

According to Hardy-Weinberg principle of genetic material,

p2 + 2pq + q2 = 1

and p + q = 1
where, p2 = frequency of population with dominant genotype
q2 = frequency of population with recessive genotype
p = frequency of dominant allele
q = frequency of recessive allele
2pq = frequency of heterozygous individual in a population

Given that, frequency of dominant allele (A) = 0.6
and frequency of recessive allele (a) = 0.4

Answer a) Frequency of AA genotype, p2= 0.6 X 0.6 = 0.36
Frequency of aa genotype, q2= 0.4 X 0.4 = 0.16
Frequency of Aa genotype, 2pq = 2 X 0.6 X 0.4 = 0.48
Frequency of dominant phenotype (AA and Aa both are the dominant phenotypes) = 0.36 + 0.48 = 0.84

Answer b) To achieve an equilibrium five conditions must be present in a population, according to Hardy-Weinberg principle. These are as follows

A population is evolving if there is a change in allelic frequency or population does not meet any of the Hardy-Weinberg's conditions.

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.