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•  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

gene pool

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•  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

mechanisms of change

TedEd Talks:  The Five Fingers of Evolution