BIO 4200(Key of midterm exam 2)

1. For the two-allele system specified below, calculate the allele frequency change for both alleles over one generation if allele A1 is represented with the frequency of 0.8 at the beginning of the experiment (8 points): Genotype: A1A1 A1a2 a2a2 Fitness coefficients: s11: 0.5 s12: 1 s22: 0.5 Fitness values: w11: 1.5 w12: 2 w22: 1.5 p‘ = w11p2 +w12pq w11p2 + w122pq + w22q2 p‘ = 1.5*0.82 + 2*0.8*0.2 1.5*0.82 + 2*2*0.8*0.2 + 1.5*0.22 p‘ = 1.28/1.66 p‘ = 0.77 correct expression (2) correct filling in of expression (2) correct calculation (2) correct interpretation (2) 2. For the allele system in question 1, describe the approximate frequency change of allele a over 10 generations using a graph (6) correct x-axis: 2 correct y-axis: 2 correct curve: 2 ' 1' 3. For the allele system in question 1, what is the final frequency of allele a? Explain your answer (4). 0.5 because this is a case of overdominance (heterozygote superiority) in which case ^p = s22/s11+s22 ' 2' 4. Calculate the linkage disequilibrium coffecient for the haplotypes specified below. Is the population in linkage equilibrium? Explain your answer (5). AB: 48 Ab: 6 aB: 16 ab: 4 total: 74 gAB: 0.65 gAb: 0.05 gaB: 0.22 gab: 0.08 4points D = gAB*gab- gAb*gaB = 0.65*0.05 – 0.22*0.08 = 0.0149 2points D NOT 0 -> Population NOT in equilibrium 1 point 5. List two causes that can lead to linkage disequilibrium? (4). Population admixture (2): mixing of two population with different D Selection of multilocus genotypes 6. Which force reduces linkage disequilibrium over time (2)? recombination