Taxonomy - History

• Taxonomy


  The identification, classification, and naming of organisms
• Subfields of taxonomy

  • Classification - arranging organisms into groups based on similarities
  • Nomenclature - the naming of organisms
  • Identification - the determination of an organism
• Aristotle's system of classification


  • Classified organisms based on several criteria: plants or animals, bloodless or red-blooded, morphology such as structure and size, habitat (air, water, land)
• Aristotle's system was limited as it was based on the view that species are distinct, separate, and unchanging, and did not account for the evolutionary relationship of organisms
• Linnaeus's system of classification


  • Classification based on morphology and behavior, used binomial nomenclature to name organisms with genus and species names in Latin
• Linnaeus is considered the father of taxonomy
• Binomial nomenclature


  Linnaeus' method of naming organisms with a two-part scientific name: genus name and specific epithet
• Phylogeny


  The evolutionary history and relationships of species
• Cladistics


  A method of hypothesizing the relationships and history of organisms based on the order they diverged from a common ancestor
• Cladogram


  A branching diagram that represents the proposed phylogeny or evolutionary history of a species or group, based on ancestral and derived traits
• Derived traits are those that an organism possesses, while ancestral traits are those that an organism lacks
• The 3 domains and 6 kingdoms of life

  • Domain Archaea - Kingdom Archaebacteria

  Domain Eubacteria - Kingdom Eubacteria

  Domain Eukarya - Kingdom Protista, Kingdom Fungi, Kingdom Plantae, Kingdom Animalia
• Organisms are placed into domains and kingdoms based on cell type and structures, number of cells, and mode of nutrition
• The taxonomic categories used in classification are arranged in a nested-hierarchical system from broadest to most specific: domain, kingdom, phylum, class, order, family, genus, species
• Taxon (plural taxa)


  A named group of organisms
• Carolous Linnaeus - Vegetabilia or Animalia

  Ernst Haeckel - Protista

  Herbert Copeland - Monera

  Robert Whittaker - Fungi

  Carl Woese - Eubacteria and Archaebacteria

  Carl Woese - Eukarya, Eubacteria, and Archaea
• Eukaryotes: Animalia, Plantae, Mycota, Protista
• No nucleus: Eubacteria, Archaebacteria
• Animalia: Eukaryotes, multicellular, heterotrophic by ingestion (last to evolve)

  Plantae: Eukaryotes, chloroplast and cellulose, multicellular, photoautotrophs

  Mycota: Eukaryotes, chitin, multicellular and unicellular, heterotrophic by absorption

  Protista: Eukaryotes, some with chloroplast and cellulose, unicellular or multicellular, can be photoautotrophs or heterotrophic by ingestion
• Eubacteria: true bacteria, prokaryotes (no nucleus), peptidoglycan, autotroph/heterotroph (normal environments)

  Archaebacteria: extreme bacteria, without peptidoglycan, autotroph/heterotroph (extreme environments)
• Systematics: study of diversity and evolutionary history relationships