Answer:
Mutation followed by natural selection made mosquitos resistant to DEET
Step-by-step explanation:
Natural selection selects beneficial alleles, which increase their frequency in the population, resulting in adaptation. Aptitude, which is the contribution of each genotype to the next generation, increases too.
In many cases adaptations, resulting from the natural selection process can be correlated to environmental factors or selective pressures applied by other organisms or habitats.
Let us remember that, a mutation is a change or alteration in DNI sequences that introduce new variants. Many of these are eliminated, but some of them might succeed and be incorporated into each individual. These mutations are the ones that have been selected by natural selection.
So, in the exposed mosquitos´ example,
- The selective pressure or modeling environmental factor is the DEET repellent.
- Some of the mosquitos mutated changing their behavior.
- The new mosquito´s response is not-detection of the repellent presence -only in those individuals carrying the mutations-.
- Natural selection benefits these mutations.
- Mosquitos survive and become more resistant
Probably some of the mosquitos in the population suffered a mutation that favored them in not detecting repellent DEET. These individuals developed resistance to the chemical and were able to survive and reproduce, enhancing population sizes again. Natural selection benefited the mutation that gave them resistance.
Let us remember that the term resistance refers to an inheritable change in the population sensitivity, reflected through the consecutive failure of the chemical effects, correctly used in order to cause an effect on the insect population.
Repellents might produce a genetic modification in the insects, leading them to not detect the chemical. Insects evolve with the capability of tolerating the DEET dose that normally is used to repel mosquitos
The excessive use of DEET leads to the fixation of new genes -by natural selection- that result from mutations in the mosquito genetic material, which makes them become even more resistant to the chemical.