There is an island with a population of 150, and recessive allele (encodes for t

Question

There is an island with a population of 150, and recessive allele (encodes for tall individuals) with a frequency of 0.001. It is assumed that mating is random and frequent. A shipwreck places 7 migrant individuals from the mainland on the island, where they mate successfully and randomly with the natives. The recessive allele frequency in the migrant population is 0.95. 1) what is the new frequency of the recessive allele after the migration event? 2) What is the ratio of tall people on the island before and after the migration event? Did the migration event raise or lower the incidence of tallness?

Explanation / Answer

Solution:

The proportion of migrants in the new population =m = 7/150 = 0.047

The frequency of theallele for curved wings in the old population =qold= 0.001;

the allele frequency in themigrant population is qmigrants= 0.95;

qnew = mqmigrants+ (1 –m)qold= 0.047(0.95) + (1- 0.047)(0.001) = 0.046

Now that we have calculated the allelic frequencies, we can calculate the new genotype frequency assuming random mating:

fnew(cv,cv) =qnew2= (0.046)2= 0.002116

The ratio of tall people on the island before the migration event = qold2 * total population befor migration * 100

= 0.0024 * 150 * 100 =36%

The ratio of tall people on the island after the migration event = qnew2 * total population after migration * 100

= 0.0462 * 157 * 100 = 33%

The migration event raised the incidence of tallness.

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