allele (uh-LEEL)
An alternative form of a gene.

gene pool
The total aggregate of genes in a population at any one time.

genetic drift
Changes in the gene pool of a small population due to chance.

genotype (JEE-noh-type)
The genetic makeup of an organism.

Hardy-Weinberg theorem
An axiom maintaining that the sexual shuffling of genes alone cannot alter the overall genetic makeup of a population.

microevolution
A change in the gene pool of a population over a succession of generations

mutation (myoo-TAY-shun)
A rare change in the DNA of genes that ultimately creates genetic diversity.