In a population of ladybugs, a change in DNA of the offspring of one bug produces entirely black bugs. These bugs are more successful in escaping predators. Overtime, this gene becomes more frequent in the population, and the ladybug population loses its red color allele. What type of evolutionary mechanism caused the change in the population?

Missing options

A. Gene flow

B. Genetic drift

C. Artificial selection

D. Mutation

Answer:

B. Genetic drift

Explanation:

The loss of particular gene as a result of death of indivduals carrying those genes is known as genetic drift. As per the question statement, a change in DNA of ladybugs produced black bugs that were more successful in escaping predators. Therefore, with the passage of time, all other individuals that do not carry this gene (rather carry red color allele) would be eaten by the predators and only black bugs would survive. This phenonmenon is known as genetic drift.

This is not a gene flow because changed gene is not being transferred. Similarly, it is a natural selection and not artificial selection where humans introduce changes. However, the change in DNA could be regarded as positive mutation. But we cannot call the whole phenomenon as mutation because it also includes selection of black bugs. So, only genetic drift is the correct option.