Evolution

• Evolution= change in inherited characteristics in a group of organisms over time.

  • Due to changes in gene frequency of different alleles within a population
• Gene pool= sum total of all genes in a given population at a given time.
• Allele frequency= how often different alleles occur in the gene pool of a population.

  • Gene pool can change over time due to natural selection.
  • When gene pool changes sufficiently over time, the characteristics will also change.
  • Over time these changes are so great that new species forms.
  • Allele frequencies can be calculated to track whether evolution is taking place.
  • Only considers one gene at a time.
• Hardy-Weinberg principle

  = If certain conditions are met then the allele frequencies of a gene within a population will not change from one generation to the next and there will be no evolution.
• Conditions for allele frequencies

  • Organisms are diploid
  • Reproduce by sexual reproduction only
  • No overlap between generations
  • Mating is random
  • Population is large
  • No migration, mutation or selection
  • Allele frequencies are equal in both sexes.
• • P represents frequency of dominant alleles.
  • Q represents frequency of recessive alleles.
  • p+q=1 (allele frequency)
• Genotype frequency

  • P(squared)= chance of individual being homozygous dominant.
  • Q(squared)= chance of individual being homozygous recessive.
  • 2PQ= chance of individual being heterozygous.
  • P(squared)+Q(squared)+2PQ= 1