Comparative Anatomy

• Comparative Anatomy

  • compares structures of different organisms
  • used to establish evolutionary relationships on the basis of structural similarities and differences - includes comparative embryology
• Homologous Structures

  • common to more than 1 species and were inherited from a common ancestor
  • structures with similar structural plan but perform different functions due to living in different environments with different selective pressures (conditions) - similar structure, different function
  • eg. forelimbs in vertebrates
  • evidence of common ancestry and divergent evolution
• Analogous Structures

  • structures with different structural plans
  • different structure, same function
  • evidence for convergent evolution
  • eg. wings of insects and birds
• Vestigial Structures

  • evolutionary leftovers - eg. coccyx, appendix
  • no longer serves a purpose
  • reduced in size to conserve energy
  • evidence of change over time
• Comparative Embryology

  • similarities between embryos of different species in early development suggest they've evolved from a common ancestor
  • evidence for divergent evolution