Question

1,000 rats live on an island (i.e. these are the natives), and the frequency of a recessive coat color allele in this population is 0.49. 180 rats from the mainland migrate to the island by stowing away in a boat. The frequency of the recessive coat color allele in these migrants is 0.76. Assuming that all rats have offspring, in the first generation after the migration, what is the frequency of the coat color allele in the new island population (i.e. q_n+1)?

       (after Chinnici and Matthes, Genetics Practice Problems and Solutions, 1999)

Answer 1

The frequency of recessive coat colour in the native population consisting of 1000 rats is 0.49. the frequency of recessive coat colour in the new rat population of 180 is 0.76.

The frequency of recessive allele in native population is,

= square root of 0.49

= 0.7

The frequency of the recessive allele in new population is,

=square root of 0.76

= 0.87

The combined frequency of recessive allele in first generation is,

= ((1000)(0.7) + (180)(0.87))/1180

=(700 + 156)/1180

= 856/1180

= 0.725