Understanding:
• A gene pool consists of all the genes and their different alleles, present in an interbreeding population
Gene Pools
A gene pool represents the sum total of alleles for all genes present in a sexually reproducing population
- A large gene pool indicates high amounts of genetic diversity, increasing the chances of biological fitness and survival
- A small gene pool indicates low amounts of genetic diversity, reducing biological fitness and increasing chances of extinction
Gene pools can be used to determine allele frequency – the proportion of a particular allele within a population
Representation of a Gene Pool
Understanding:
• Evolution requires that allele frequencies change with time in populations
Evolution is the cumulative change in the heritable characteristics of a population across successive generations
- This requires that allele frequencies change within the gene pool of the population to reflect these evolving characteristics
Mechanisms of Change
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
Mechanisms for Changing Allele Frequency within a Gene Pool
TedEd Talks: The Five Fingers of Evolution