natural selections

• what is natural selection?

  the way organisms change over time as they adapt to their changing environments
• survival of fittest?


  refers to survival of best adapted
• evolution?

  change in allele frequency in a population over time
• model answer for evolution?

  • population has naturally occurring genetic variation with new alleles created through mutations in DNA.
  • change in environment= change in selection pressure
  • allele becomes favourable, organism now has selective advantage
  • organisms with allele more likely to survive, reproduce and pass onto offspring
  • allele frequency increased
• how to calculate allele frequency?

  hardy weinburg equation (if assumed gene only has 2 alleles) freq dominant allele= p freq recessive allele= q

  • p2 + 2pq + q2 = 1