Answer:
Natural selection has been studied since Charles Darwing first started his research.
Explanation:
Basically natural selection changes the frequency of traits. Left themselves in large , freely interbreeding populations, the frequency of traits will remain the same from generation to generation. The traits are often heritable, in living organisms, many characteristics are inherited, or passed from parent to offspring.
The reasons why we mightt not see a response to directional selection on such a trait are: