Modern Classification & Variation

• Convergent evolution – unrelated species adapt to very similar habitats so develop very similar features
• New technologies (e.g. better microscopes) have resulted in new discoveries, so classification must be revised
• Classification using biological molecules:

  • Two closely related species which have RECENTLY evolved into separate species, will have very similar biological molecules

  • Two distantly related species that evolved into separate species LONG AGO will have less similar biological molecules
• Classification using DNA

  Taxonomists compare the base pair sequences of species

  • Closely related species have more similar sequences
  • More distantly-related species = differences in their base pair sequences
• modern taxonomists use a wider range of evidence:

  – Behavior

  – Anatomy/morphology and physiology

  – Embryology

  – Fossils
• Cytochrome C

  A protein used in respiration – found in all eukaryotic organisms (in mitochondria)