In the south of France mosquitoes can be a nuisance. As the economy is dependent in part on tourists, this can be problematic. So they spray insecticides to kill the mosquitoes. The heroic mosquitoes had an allele for a gene in their gene pool that resists the insecticide. The two graphs below show the frequency of the resistance allele in two different seasons and two different years. The x-axis is distance from the cost. Note, that spraying stops at about 20 km from the coast. Spraying only happens in the summer? Why might the allele frequency fall so quickly at the coast in the winter?
Select one:
a. Thee allele is advantageous when there is no spraying
b. There is a fitness cost to the allele, so as soon as selection for the allele stops, it's frequency drops.
c. Because there is no gene flow between the fall and summer mosquitoes, the allele will not be passed between them.
d. Genetic drift eliminates many mosquitoes because of spraying, so the allele frequency goes down.