Evolutionary Classification

• Taxonomy


  The branch of biology concerned with identifying, naming and classifying
• Linnaean Classification System


  One of the most widely used classification systems
• Linnaean Classification


  • Organisms are classified into hierarchical taxa (groups)
  • Based on easily observable visible characteristics
• Binomial Nomenclature


  • A two-word naming system developed by Linnaeus
  • The first part is the Genus, the second part is the species
  • The Genus is always capitalized, the species is always lower case
  • The entire name is in italics
• Scientific names are unique to each species and are descriptive of an important trait or the organism's habitat
• Common names can be confusing as they vary between languages and from place to place
• Not all characteristics that are in common, such as color, mean that something is related because they vary between species
• Sometimes structures have the same function but are unrelated because the similarities were caused by selective pressures not by ancestry
• Systematics


  Focuses on classifying organisms and determining their evolutionary relationships
• Phylogeny


  The evolutionary history of a species
• Evolutionary Classification (Phylogenetic Systematics)


  Groups species into larger categories that reflect lines of evolutionary descent rather than overall similarities and differences
• Clade


  A group of species with a single common ancestor, including all the descendants of that ancestor that are living or extinct
• A clade must be a monophyletic group (includes a single common ancestor and all of its descendants)
• Some of the taxa in the Linnaean classification system were paraphyletic (the group includes a common ancestor but excludes one or more groups of descendants)
• Cladogram


  A phylogenetic tree that links groups of organisms by showing evolutionary lines branched off from a common ancestor
• Cladogram


  • Node - the last point at which the two new lineages shared a common ancestor
  • Shared ancestral character - a trait that is common to members of a particular clade and is found in its ancestor
  • Shared, derived character - a trait that is common to members of a particular clade but originated in an ancestor
• Whether or not a character is derived depends on the level of grouping
• Smaller clades are nested within larger clades
• Sometimes derived characters are lost by an organism but the ancestor had the derived character
• DNA evidence is the most recent means of determining derived characters
• The more derived genetic characters, the more recent the common ancestor
• The more derived genetic characters, the more closely related the organisms are
• 3 Domains and 6 Kingdoms

  • Domains: Bacteria, Archaea, Eukarya
  • Kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia
• Domains and Kingdoms


  • Cell Type: Prokaryote, Eukaryote
  • Cell Structures: Cell wall with/without peptidoglycan, Cell wall of chitin, No cell walls
  • Number of Cells: Unicellular, Multicellular, Colonial
  • Mode of Nutrition: Autotrophic, Heterotrophic