- Offspring are similar to parents
- No two individuals are identical
- Organisms can produce large numbers of offspring
- Populations remain stable in size
Darwin concluded:
- There is a struggle to survive
- This is selection pressure
- Better adapted individuals survive and pass on their genes
- Over time a number of changes giving rise to a new species
- Organisms in species show variation, differences in the genes
- Those best adapted have increased chance of survival and successful reproduction
- Repeated for many generations and so proportions of individuals with the adaptation increases
- Repeated over multiple generations, this leads to evolution.
Darwin’s notebook