1.In biology, evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection. The theory of evolution is based on the idea that all species? are related and gradually change over time.
2.Survival of the fittest is a simple way of describing how evolution (the process by which gradual genetic change occurs over time to a group of living things) works. It describes the mechanism of natural selection by explaining how the best-adapted individuals are better suited to their environment.