selection

evolutionary forces

• selection

• migration

• genetic drift

• mutation

adaptation

• 2 types

  • physiological/behavioral

  • genetic

phenotype plasticity

physiological/behavioral adaptation

natural selection

• long-term genetic response to environmental change

• adaptive evolution

relative fitness

• w

• fitness / fitness value relative to your most fit genotype

selection coefficient

• s

• 1 - relative fitness

directional selection

stabilizing selection

disruptive selection

directional selection

• one allele is the most fit

• 
  Change in frequency of bad allele Δq:
  Δq = -spq2 / (1 – sq2)
  o Always declines in frequency
  o Bad allele will eventually go to a frequency of 0
  o Rate of decline slows at lower frequencies
  o Rate of decline depends on amount of selection (s

stabilizing selection

• overdominance, balancing selection

• heterozygote is the most fit