16.1 - Genetic Variation in Populations

• Genetic Variation

  • Evolution can only occur in species if there is genetic variation
  • 2 Main Sources of Genetic Variation
  • gene shuffling
  • crossing-over increases the number of genotypes in offspring
  • sexual reproduction/meiosis produces different phenotypes in offspring
  • mutations
• Genetic Variation in Gene Pools

  • Genetic variation is studied in gene pools
  • A population is a group of individuals of the same species that interbreed, living in the same place
  • A gene pool consists of all the different genes & alleles that are present in a population
  • The frequency of an allele = the number of times the allele occurs in a gene pool, divided by the number of alleles for a gene
  • measured in % and expressed as a decimal
• Evolution in Genetic Terms

  • Evolution is really a change in the frequency of alleles in a population
  • Alleles determine phenotypes, so if the frequency of alleles changes in a gene pool... then the phenotypes change and the population is evolving