Question

Selection for insecticide resistance is very strong, Curtis et al. estimated the relative fitness in the mosquito, Anopheles culicifacies, an important vector for malaria in Asia. They estimated the finesses of the three genotypes, SS, SR and RR (S is susceptible, and R is resistant) under exposure to the insecticide DDT based on the assumption that resistance is dominant. 12pts

Relative Fitness:

Species                                    Insecticide                  SS        SR       RR

Anopheles culicifacies            with DDT                    0.35     1.0       1.0

                                                without DDT               1.0       0.83     0.65

1. What is the equilibrium frequency (p~) of An. culicifacies R gene under DDT exposure? Without DDT exposure?
2. What is the mean relative fitness for + DDT and – DDT for An. culicifacies?
3. What does the (w bar) value mean in terms of selection?

Answer 1

☆ Under equilibrium frequences of each allele tp (For R) & 0.5 and d (s) = 0.5. genotype frequency.. $2(RR) = 04 205, 04(95) = 0:25, 250 - 0.15 Now under selection pressures Equilibrium frequency of gene or Rallele Co With DDT (0-25 X 17 * 30.5X1) = 0:5 Co Without DOT - $(0.25 X0.66) +(0.5X0.83)/2] }=0.37 ® Mean relative fitness for.. © + DPT-{(0.35 0.25)+61X0.5) + (1x 0.25) p=0.8375 (6) DDT -{C180125)+(9:83X0.5) +(0,65X0.25)=0.8275 © W bar rebresent the average fitness among the bobulation under selection, for eso subbore filmess of genopy be p² is Wu d² is wee 1 and 2 bd = Wir; tham, ... W = $(x Wn) + (950 x W12) +(9?x W22)?.