Answer:
By semiconservative replication.
Step-by-step explanation:
DNA is the genetic material of living organisms. They replicate in a semiconservative method where one strand is from the parents and the other is a new one. Thus every offspring have some new characters along with the characters of their parents. Thus DNA replication does the variation which results in natural selection. By the process of natural, new and better-adapted organisms come to existence. Thus DNA works to the reinforcement of the organisms.