Natural english pre intermediate pdf

Natural english pre intermediate pdf biology began in the nineteenth century with Charles Darwin’s work on evolution by natural selection. Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.


It is a key mechanism of evolution, the change in heritable traits of a population over time. Charles Darwin popularised the term “natural selection”.

He compared it with artificial selection, which is intentional, whereas natural selection is not. Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and offspring can inherit such mutations.