Natural selection and it's evolutionary consequences provide a scientific explanation for

It provides a scientific explanation to the Survival of the Fittest. Animal species must adapt to their environment to survive the wild

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.