7. In humans, ABO blood type is controlled by a single gene with 2 codominant al

Question

7. In humans, ABO blood type is controlled by a single gene with 2 codominant alleles (IA and IB ) and one recessive allele (i). The population of humans in the city of Xanadu is 7568. 1874 of these people have blood type O and 1243 of these people have homozygous blood type A.

b. (2 points) If a disease suddenly appears that kills 60% of all people with type A blood (leaving 40% alive), kills 40% of all people with type AB blood, kills 10% of all people with type B blood, and kills 5% of all people with type O blood, what is the relative fitness for each blood type (assume the disease continues to kill the same percentages of people each generation)?

c. (3 points) Using the relative fitness values you calculated in part (b), determine what the allele frequencies of the IA, IB and i alleles will be when the population of Xanadu has again reached Hardy-Weinberg equilibrium.

d. (3 points) This same disease has affected a different human population on the island of Atlantis. This population is smaller and contains 1251 individuals. Of these, 398 are blood type O and 217 are homozygous blood type B. This population has been on the island for many generations, and therefore consists of individuals that are related to each other by descent. The inbreeding coefficient in this island population is 0.08. Assuming that the disease kills the same proportions of people as in part (b), what will be the frequencies of each blood type in this island population when Hardy-Weinberg equilibrium is reestablished?

Explanation / Answer

Information is incomplete. People with blood type A and O are mentioned, but either of the people with blood type B or AB has to be mentioned otherwise relative fitness of each blood type cannot be calculated. The remaining people that is calculated by deducting people having blood type A and O form the total (i.e, (7568- (1874+1243)) =4451) signifies people having both blood type B and AB which is not enough to calculate the relative fitness.

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