Classification

• Classification


  Organising Living Organisms into Groups
• Traditional classification system


  1. Organisms grouped according to their characteristics and the structures that make them up

  2. Divided into kingdoms

  3. Kingdoms subdivided into smaller groups: phylum, class, order, family, genus, species
• Classification systems change over time
• Three-domain system


  1. Organisms split into three large groups called domains: Archaea, Bacteria, Eukaryota

  2. Domains then subdivided into smaller groups: kingdom, phylum, class, order, family, genus, species
• Binomial system


  Every organism given a two-part Latin name: genus and species
• Binomial system used worldwide to avoid confusion
• Evolutionary trees


  • Show how different species are related to each other
  • Show common ancestors and relationships between species
  • More recent the common ancestor, the more closely related the two species
• Analysing evolutionary relationships


  1. Use current classification data (e.g. DNA analysis, structural similarities) for living organisms

  2. Use information from the fossil record for extinct species
• Evolutionary relationship


  • Whales and dolphins have a recent common ancestor, so are closely related
  • Whales and dolphins are more distantly related to sharks