Macrotaxonomy

• Why Do We Classify Organisms?

  • Biologists group organisms to organize and communicate information about their diversity, similarities and proposed relationships.
  • Classification systems change with expanding knowledge about new and well-known organisms.
  • Approximately 1.75 million species have been classified so far.
• History of Classification

  • Aristotle (2000 + y.a.) classified organisms as either plants (by size) or animals (red-blooded or not).

  
• History of Classification

  In the 1700s and 1800s:

  • Carolus Linnaeus, a Swedish botanist, used similarities and differences in morphology and behavior to classify birds.
  • Linnaeus developed the first taxonomy system and made it possible to include evolutionary principles in classification in the 1800s.
  • Jean-Baptiste Lamarck, Charles Darwin, and Ernest Haeckel introduced classification systems based on evolutionary relationships to organize biological diversity.
• Scientific Names

  • Carolus von Linnaeus devised the currently used binomial nomenclature.
  • Two-word naming system:
  • Genus
  • Noun, Capitalized, Underlined or Italicized
  • Species
  • Descriptive, Lower Case, Underlined or Italicized
• Hierarchical Classification into Taxa

  • Taxonomists classify organisms by dividing them into smaller groups based on more specific criteria. A named group of organisms is a taxon.
  • Taxonomic categories (taxa):
  • Kingdom: King
  • Phylum: Philip
  • Class: Came
  • Order: Over
  • Family: For
  • Genus: Green
  • Species: Spaghetti

  Beginning with species, each category becomes progressively more comprehensive. Ex.: while the leopard, tiger and domestic cat all belong to different genera, they are grouped together in the same family.