How does Natural Selection occur?

In the population of a species there will always be a selection pressure (new predator/competitor/ presence of disease) There is genetic variation within the population so new alleles can arise due to random mutations This mutation is advantageous as it can help the mutated organisms to out-compete the organisms without the mutation These organisms are more likely to survive and reproduce they pass on their mutated alleles to their offspring Over generations there is a change in allele frequency as more organisms inherit the mutation Organisms without the mutations do not survive as they are out-competed