Genetic Variation: the raw material for evolution?

Question

A) Explain three cellular and/or mlecular mechanisms that introduce variation into the gene pool of a plant or animal population.

B) Explain the evolutionary mechanisms that can change the composition of a gene pool.

Help, please?

Answer 1

A) Mutations, recombination and chromosomal rearrangements

B) Mutation (introduce variation)
Migration (also called gene flow, introduces new genes)
Genetic drift (associated with founder effects and such, a random selection of small numbers often results in changes to the gene pool)
Selection (changes in selection pressures eliminate differents parts of the gene pool)
Non-random breeding (controlled breeding causes the increase of some genes at the cost of others)

Answer 2

A) Recombination
Hybridization

--Can't think of a third one right now but will add it when i do :)

B) Directional Selection
Stabilizing Selection
Disruptive Selection