Chapter 18

7.  The frequency of an allele in a population can be altered by natural selection, mutation, migration, and genetic drift.

11.  The frequency of b is , and the frequency of B is p = 1 − q = 0.8. The frequency of B/B is p2 = 0.64, and the frequency of B/b is 2pq = 0.32.

14. 

  1. p′ = 0.5[(0.5)(1.0) + 0.5(1.0)]/[(0.25)(1.0) + (0.5)(1.0) + (0.25)(0.7)] = 0.54

  2. 0.008

13.  (0.02) + (0.02)2 = 0.0102

21. 

26. 

  2. 1/8 = × (1 + FA), so FA = 0

29.  pA = pa = pB = pb = 0.5. At equilibrium, the frequency of doubly heterozygous individuals is 2(pApa) × 2(pBpb) = 0.25

31.  Before migration, qA = 0.1 and qB = 0.3 in the two populations. Because the two populations are equal in number, immediately after migration qA + B = (qA + qB) = (0.1 + 0.3) = 0.2. At the new equilibrium, the frequency of affected males is q = 0.2, and then frequency of affected females is q2 = (0.2)2 = 0.04. (Color blindness is an X-linked trait.)

33.  q2 = 0.002. q = 0.045. Assuming F in the founders is 0.0, the F50 = 0.222 (see Box 18-3). fa/a = q2 + pqF = 0.012.

37. 

41. 

  1. Genetic cost = sq2 = 0.5(4.47 × 10−3)2 = 10−5

  2. = 6.32 × 10−3

    Genetic cost = sq2 = 0.5(6.32 × 10−3)2 = 2 × 10−5

  3. Genetic cost = sq2 = 0.3(5.77 × 10−3)2 = 10−5