Evolution
Biology: Edexcel IGCSE, topic 4.3.12
The Evidence for Evolution
The discovery of genes as a mechanism (way) to inherit characteristics and create variance supported the theory of evolution. In addition to this, the two main sources of evidence are:
Fossils
- Fossils show the gradual changes in organisms over vast periods of time.
Antibiotic-resistant bacteria
- Natural selection neatly explains this phenomenon:
- Bacteria reproduce rapidly.
- Mutations occur during reproduction.
- If a mutated bacterium is resistant to antibiotics, it will survive exposure to antibiotics and go on to reproduce.
- This bacterium will represent the original ancestor of a new resistant strain.
Test yourself on Evolution
Apart from genes, what are the two main sources of evidence for evolution?
Why is antibiotic-resistant bacteria evidence of evolution?