Assignment task: The following information is relevant for questions.
The diamondback moth is a pest of Brassica vegetables in Australia. Pyrethroid insecticides have been relatively successful in controlling the pest for ten years, however, a single point mutation has arisen that has developed an allele (PR) that causes resistance. A cross between a susceptible line (PSPS) and a resistant line (PRPR) produce heterozygous F1 offspring (all PRPS). A second cross was then performed between F1 x F1 individuals to produce the second generation, F2.
Q1. Provide the expected genotype ratios among the F2's.
Q2. The progeny from this cross were produced and these F2 caterpillars were fed on cabbage that had been sprayed with insecticide. The surviving adults were genotyped to produce the following data:
30 PSPS + 120 PRPS + 250 PRPR
Calculate the frequency of the resistant allele in the surviving population.
Q3. Determine the expected number of individuals for each genotype among this population if the resistant gene did not provide a selective advantage.