Evolution

• Gene pool


  All the genes and their different alleles, present in an interbreeding 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
• Allele frequency


  The proportion of a particular allele within a population
• Evolution requires that allele frequencies change with time in populations
• Mechanisms of change in allele frequency within a gene pool (evolution)


  • Mutation
  • Gene flow
  • Sexual reproduction
  • Genetic drift
  • Natural selection
• 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