Question

A researcher is culturing several different strains of bacteria in the same petri dish. One day, he finds that all of the strains have died off except one. He continues to grow his bacteria for several weeks, and new strains develop. However, after a month he again notices that all but one of his bacterial strains have died off. This is an example of:

Answer 1

Answer:

Periodic selection.

Explanation:

Some bacterial strain has the ability to develop the resistance against the particular drug. This helps the bacteria to survive against the adverse environmental conditions.

The periodic selection may be defined as the natural selection that selects some strains of the bacteria that can survive in the particular environment. The periodic selection also favors the adaptive mutation that might occur due to the recombination in bacteria and removes the non selective species. The information given in the question provides the example of periodic selection.

Thus, the answer is periodic selection.