Question 1
Paper 2Medium16 marksIn a moth population, wing pattern is controlled by two alleles, B and b. The B allele gives dark wings and is dominant; moths with genotype bb have pale wings. Treat the counts below as the complete populations, so ignore sampling error.
| Generation | Population information |
|---|---|
| 1 | 1000 moths; 160 have pale wings |
| 2 | 1000 moths; 400 BB, 400 Bb and 200 bb |
Assume generation 1 is in genetic equilibrium. Allele counting in generation 2 gives p = 0.60 and q = 0.40. Records of the mating pairs that produced generation 2 show that moths preferentially mated with partners having the same wing pattern.
State what p and q represent for this gene and give their relationship.
Calculate p and q for generation 1, and the expected frequencies of BB, Bb and bb.
Calculate the observed genotype frequencies in generation 2. Determine whether they fit the Hardy–Weinberg equation for the allele frequencies given.
Explain how the mating pattern could account for the genotype frequencies in generation 2.
State three conditions, other than random mating, required for a population to remain in genetic equilibrium.