Question

The frequency of a recessive allele q in an island population is 0.8 and the frequency of allele q in a mainland population is 0.3. One season, some individuals from the island migrate to the mainland. After this migration, 20% of the mainland population consists of migrants from the island. What will be the frequency of allele q in the mainland population in the next generation?

a) 0.4

b) 0.5

c) 0.1

d) 0

e) 0.6

Answer 1

Frequency of q in Island population = 0.8

Frequency of q in mainland population = 0.3

Some individuals from Island migrate to mainland. After this mainland population has migrants = 20% or m = 0.2 (migrants frequency).

So non-migrants is given by = 1 - m = 1 - 0.2 = 0.8

Frequency of allele q in mainland population in next generation. Next generation = t + 1.

It is given by formula ;

Pq (t+1) = Pqm (1 - m) + Pqi * m

Where Pq (t + 1) = frequency of p in mainland after migration in next generation.

Pqm = initial frequency of q in mainland = 0.3

Pqi = initial frequency of q in Island = 0.8

So, putting values in formula :

Pq (t + 1) = 0.3 (1 - 0.2 ) + 0.8 * 0.2

= 0.3 * 0.8 + 0.16

= 0.24 + 0.16

= 0.40

= 0.4

Correct answer Option A, 0.4