Chapter 2 of 10All chapters
Chapter 2 of 10
Where variation comes from
Mutation and shuffling.
Mutation
Copying DNA introduces occasional errors, at random with respect to what would be useful. Most are neutral, some harmful, and a few happen to help in a given environment.
- The environment does not direct mutation; it only filters the results.
- Radiation and certain chemicals raise the rate, not the usefulness.
Recombination
Sexual reproduction shuffles two parental genomes into new combinations every generation. That is why siblings differ and why variation persists in large populations.