Describe the theory of natural selection

In each generation more offspring are produced than it is possible for the environment to support each individual in the offspring has to compete and struggle to survive in order to reproduce and pass on its genes every individual in a population displays slightly different phenotypes due to random mutations. The individuals that possess characteristics that are better adapted to their environment are most likely to survive these individuals have advantageous DNA sequences which are non randomly selected for The less beneficial DNA sequences are gradually removed from the population as individuals displaying these characteristics have a reduced survival rate and chance of reproducing. They have deleterious DNA sequences which are non randomly selected against.