ABSTRACT
The total set of genes and alleles present in a population is known as the gene pool. Populations that are separated from one another and do not interbreed will have separate gene pools. The presence of a number of different alleles resulting in more than one phenotype in a population is termed a polymorphism. Unlike adaptation genetic drift is a change in allele frequency in a population that cannot be ascribed to natural selection. Evolution is a change in allele/gene frequencies over time that occurs as less adapted alleles are replaced with better adapted ones. Genetic drift is a random change in gene frequency arising through chance, and tends to be more apparent in small populations. Drift occurs because of the influence of chance on which genes are transmitted from one generation to the next. Not all individuals mate and not all of the gametes produced by an individual contribute to reproduction.
