Natural Selection (MFE)

• Natural Selection

  • occurs when selection pressure in the environment grant a selective advantage to a phenotype to enhance survival and reproduction
  • leads to changes in allele frequency in a population's gene pool
  • individuals that have certain traits are more likely to survive and reproduce at higher rates than others
• Principle 1: Variation

  • individuals in a population differ from one another and show variation
  • variation is caused by mutations in alleles and meiosis/sexual reproduction processes
  • processes include crossing over, independent assortment, and random fertilisation and mating
• Principle 2: Selection Pressures

  • there are more individuals produced in a population than the environment can support
  • environmental resources are limited
  • selection pressures favour those with more advantageous traits
  • may lead to competition between individuals and those with advantageous traits may outcompete others
• Principle 3: Survival

  • "survival of the fittest"
  • individuals who are better suited to the environment are more likely to survive and reproduce
  • not all individuals are able to survive to reproduce
• Principle 4: Reproduction

  • individuals with the inheritable advantageous traits are more likely to survive and reproduce
  • advantageous alleles are passed onto offspring as individuals who carry them have a higher reproduction rate than those who don't
• Principle 5: Change in Allele Frequency

  • over generations, the frequency of advantageous traits increases
  • over many generations, advantageous alleles may become fixed and disadvantageous may become lost/extinct
• Principle of Natural Selection

  Variation, Selection Pressures, Survival, Reproduction, Change in allele frequency