Population Genetics

Biol370 – Assignment # 3 Population Genetics (30pts)

Q1. Consider 10 populations that have the genotype frequencies shown in the following table (15pts):

Genotype f(D)

(2 decimals) f(d)

(2 decimals) c2

(2 decimals)

H/W equilibrium?

(Yes/No) Pop. D/D d/D d/d

1 0 0 1 2 0 1 0 3 1 0 0 4 0.5 0.25 0.25 5 0.25 0.5 0.25 6 0.25 0.25 0.5 7 0.33 0.33 0.33 8 0.04 0.32 0.64 9 0.64 0.32 0.04

10 0.986049 0.013902 0.000049

a. What are f(D) and f(d) in each population? (fill the table, use 2 decimals)

b. Which populations are in Hardy-Weinberg equilibrium? (use c2-test, fill the table, use 2 decimals) c2 data need to be provided!

Q2. The hemoglobin B gene (Hb) has a common allele (A) of SNP (rs 334) that encodes the HbA form of (adult) hemoglobin and a rare allele (T) that encodes the sickling form of hemoglobin, HbS. Among 571 members of the Yoruba tribe in Nigeria, 440 were A/A and 129 were A/T, and 2 were T/T individuals. Use the c2 test to determine whether these observed genotypic frequencies fit Hardy-Weinberg expectations (10pts).

Q3. (Challenging, 5 pts) Of 31 children born of father-daughter matings, 6 died in infancy, 12 were abnormal and died in childhood, and 13 were normal. From this information calculate roughly how many recessive lethal genes we have, on average, in the human genome. (Hint: if the answer were 1, then the daughter would stand a 50% chance of carrying the lethal allele, and the probability of the union’s producing a lethal combination would be 1/2 * 1/4 = 1/8. So, 1 is not the answer.) Discuss the possibility of undetected fatalities in utero in such matings. How would they affect your result?