pastorkevin73 said:
I think I understand what you are saying. It seems that this has to do what what needs to change. How does mutation and recombination get the information for how to change?
To add to what Lady Kate said:
Mutation is change. Mutation happens whenever the genome is not copied perfectly. Mutation is the source of variation in various traits.
How does the genome get information on which changes to keep and which to discard? From the environment in which it finds itself. IOW through natural selection.
Recombination is a different matter. It does not deal with the variation in traits, but with the variation in individuals due to differing combinations of traits.
Here is the difference:
Suppose there is a population in which everyone has brown eyes. Then a mutation in the pigment-producing genes causes one person to have blue eyes and this is passed on to his/her descendants.
Now this trait (eye colour) exists in two variants.
That is genetic diversity due to mutation.
Suppose a population has two eye colours and two hair colours (black and red).
From the independent combination of these two traits one can get four unique individuals.
black hair + brown eyes
black hair + blue eyes
red hair + brown eyes
red hair + blue eyes
However such recombinations can only happen if there is already variation in the individual traits (hair colour, eye colour). If, as in our first example, the population only had brown eyes, then only two combinations could occur: black hair + brown eyes, red hair + brown eyes. It is only when mutation adds the new choice of blue as well as brown eyes that more combinations become possible.
Now suppose that a mutation occurred that affected hair colour, allowing for blonde as well as black and red. Now there are six possible combinations of hair and eye colour.
So mutation is fundamental to introducing variants in the first place. Natural selection comes into play when one of the variants is more adaptive than the others.