Question

A mainland and an island are both inhabited by brown and white mice. Allele A1 codes for brown coat color; allele A2 codes for white coat color. A1 is dominant to A2 .

Mice do not swim between the mainland and the island, and there are no shipping routes to the island, thus mice cannot hitch a ride on ships. During storms, however, some mice get "rafted" to the island on logs.

The island contains 240 mice. The frequency of the A1 allele is 0.85; the frequency of the A2 allele is 0.15.

On the mainland, the frequency of the A1 allele is 0.55; the frequency of the A2 allele is 0.45.

During a severe storm, 60 mice from the mainland are rafted to the island. What are the new frequencies of A1 and A2 on the island after the storm?

Enter your answer as two numbers (each to two decimal places), separated by a comma. (Example: 0.56, 0.44)

Answer 1

0.79, 0.21

Explanation:

The frequency (f) of an allele A =
`(number of copies (i))/(population of sample size (N))`

`f=\frac{i/N}`

i= f × N

at the island:

Total number of mice on the island = 240

frequency of A1 allele = 0.85

frequency of A2 allele = 0.15

no of copies of A1 allele =0.85 × 240

=204 A1

no of copies of A2 allele = 0.15 × 240

= 36A2

at the mainland:

60 mice are rafted from the mainland to the island i.e no of mice on the mainland before they were being rafted = 60

frequency of A1 allele =0.55

frequency of A2 allele = 0.45

no of copies of A1 allele = 0.55 × 60

=33 A1

no of copies of A2 allele = 0.45 × 60

=27 A2

Total new number of mice on the island= 240+60= 300

New frequencies of allele A1 will be:

(no of copies of A1 allele on island and mainland / Total new number of mice on the island(population of sample size))

=204+33/300

=0.79 A1

New frequencies of allele A2 will be:

(no of copies of A2 allele on island and mainland / Total new number of mice on the island)

36+27/300

=0.21 A2