10.3 Gene Pools and Speciation

Virtual Fruit Fly Lab

Mechanisms for Changing Allele Frequency within a Gene Pool

Changes to allele frequency within a gene pool (evolution) can result from five key processes:

• Mutation: A random change in the genetic composition of an organism due to changes in the DNA base sequence

• Gene flow: The movement of alleles into, or out of, a population as a result of immigration or emigration

• Sexual reproduction: Sex can introduce new gene combinations and alter allele frequencies if mating is assortative

• Genetic drift: The change in the composition of a gene pool as a result of a chance or random event

• Natural selection: The change in the composition of a gene pool as a result of differentially selective environmental pressures