Explain the process of evolution

Individuals within a population show a wide range of variation due to differences in their genes. The individuals within these species/populations with the characteristics most suited to their environment survive to reproduce whilst the others may die before reproducing. This means the genes and advantageous characteristics of the surviving individuals can be passed on to their offspring, whilst those of the other individuals are less likely to be passed on. This process is called natural selection. Eventually more and more of the new generation will have these advantageous characteristics as this process continues - they will have evolved to acquire/lost a particular characteristic