Gene Flow

• Theory of Evolution 


  States that all organisms developed from previous organisms and that all living things have a common ancestor in some initial form of primitive life
• Mechanisms


  Cause the basis of evolution; changes in allele frequencies within a gene pool
• Population 


  A group of organisms of the same species living together in the same place, at the same time
• Species 


  A group of individuals that share the same characteristics, can interbreed to produce fertile offspring
• Gene Pool 


  Sum of all the different alleles in a given population
• Allele Frequency 


  How often each allele of a gene occurs in the gene pool for that population
• Variation 


  Results from inheritance of different combinations of genes and by exposure of individuals to differing environments
• Genetic Variation

  • individuals in a species carry different alleles that are located at a specific position on a specific chromosome
  • any change in gene/allele frequencies within a population or species is evolution
• Mechanisms of Evolution

  • gene flow
  • natural selection
  • mutations
  • sexual selection
  • genetic drift
• Gene Flow 


  The movement/transfer of alleles into or out of a population

  • results from the migration of individuals from 1 population to another - this can be due to immigration and emigration
  • the overall effect of gene flow is to counteract natural selection by creating less differences between populations
• Isolation

  • cultural, structural, geographical, and religious barriers create, over time 2 populations
  • as isolation continues, 2 separate gene pools are created, resulting in slightly different characteristics being selected in 1 population compared to the other
  • over time allele frequencies will change, depending on which characteristics are favoured for survival
• Mechanisms for evolution are examples of microevolution