3.31- Evolution

Describe the process of evolution by means of natural selection

Evolution:

• Change in the form of organisms
• Change in the frequency of alleles

Natural selection is the mechanism of evolution. (first proposed by Charles Darwin)

Eg:
Staphylococcus aureus which causes skin and lung infection

• The original form is susceptible to to being killed by antibiotic. This is known as MSSA
• It then, by random mutation, forms a form which is resistant to antibiotics. This is known as MRSA
• The change to MRSA caused the change in the frequency of the alleles and the frequency of the resistant form increased