Question

Examples of evolution and natural selection at work include which of the following? (choose all that apply)

a.		The case of the bacteria Staphylococcus aureus resistance to first penicillin, then methicillin, and now vancomycin.
b.		Housefly resistance to DDT within a decade of its introduction.
c.		Weed resistance to herbicides
d.		The progression of metastatic cancer and failure of chemotherapy drugs over time to stop some forms of cancer.
e.		All of the above

Answer 1

e. All of the above.

Natural selection is a key of evolution by which organisms with better adaptive characteristics survive than with less adaptive ones.

In the case of bacteria overuse and misuse of antibiotics against Staphylococcus, made it to evolve in an adaptive form with the environment. Since bacteria can produce several generations within one day, this can happen very quickly. Thus bacteria have become resistant to antibiotics. The strongest bacteria are the last to die and the antibiotics sometimes do not kill all of them.

Similarly house flies and weeds survived making better adaptations to the surviving enviroments. Failure of chemotherapy drugs on cells made the natural selection and survival of cancer cells leading to its progression.