Allelic Frequency

• Allelic Frequency


  The number of times an allele occurs in a gene pool compared to the number of times other alleles for the same gene occur
• An individual cannot "adapt" to its environment, evolutionarily speaking
• Allele


  Slightly different versions of the same gene
• How new variation (alleles) arise

  1. Random mutation

  2. Mistakes in DNA replication

  3. Radiation or chemicals

  4. Viruses
• Gene Pool


  All the different alleles that are present in a population
• Evolution (in genetic terms)


  Any change in the frequency of alleles in a population over time
• No change to the allelic frequency means the population is in genetic equilibrium, even if the phenotypic frequency is changing
• Change to the environment (e.g. adding bees)

  Changes the allelic frequency
• Allelic frequencies cannot change if there is no genetic variation within a species
• Sources of genetic variation besides mutations

  • Gene shuffling/recombination
  • Crossing over
  • Independent assortment
  • Random fertilization
  • Lateral gene transfer/gene flow
• Lateral gene transfer is common in bacteria