Taxonomy and Classification

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Taxonomy and Classification

• Biology I

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Why Classify?

• 3 - 20 million species on Earth
• Less than 2 million have been identified and
  named
• Rainforests have lots of unidentified species
• Need a way to organize to make organisms easier
  to identify and relationships easier to understand

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What are Classification and Taxonomy

• Classification - Grouping based on similarities
• Taxonomy branch of biology concerned with the
  grouping and naming of organisms

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History of Classification

• Aristotle
• First to Classify living things
• Two major groups - Plants and animals
• Within these groups, organisms were organized
  based on where they lived
• Doesnt work
• Some live in both land and water
• Does NOT show relationships among organisms

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History of Classification

• Carolus Linnaeus
• 1707 1778
• Based classification system on physical
  characteristics
• Came up with BINOMIAL NOMENCLATURE
• System of naming
• 2 words gives species name
• Genus
• Group of closely related species
• Second descriptive word
• Example Homo sapiens Canis domesticus

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Why Latin?

• Dead language
• Never changes
• Consistent

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Characteristics Used by Taxonomists to Classify
Organisms

• External and internal structures (anatomy)
• Chemical make up
• DNA
• Proteins
• Evolutionary relationships

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How Our Classification System Works

• Organisms are grouped into a series of categories
  TAXA
• The taxa are
• Kingdom largest, most general group/taxon
• Phylum
• Class
• Order
• Family
• Genus
• Species smallest, most specific group/taxon

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Names and Classification show Relationships

• Bobcat Lynx rufus
• Lynx Lynx canadensis
• Bobcat and Lynx belong to the same genus
• Their classification
• Kingdom Animalia
• Phylum Chordata
• Class Mammalia
• Order Carnivora
• Family Felidae
• Genus Lynx

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How are relationships determined?

• Evolutionary History
• Structures of modern organisms are compared with
  those of fossils
• Phylogeny is created
• Evolutionary history of a species

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How are relationships determined?

• Development
• Embryonic/larval forms of species can reveal
  relationships and suggest common origin

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How are relationships determined?

• Biochemistry
• The more nucleotide sequences OR amino acid
  sequences that are shared by two species, the
  more closely related they are
• This is the BEST way to determine relationships
• Objective
• Quantitative

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How are relationships determined?

• Behaviors
• Mating calls and other behaviors lead to
  reproductive isolation and are used to identify
  species

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Our 6 Kingdom System

• Eubacteria
• Archaebacteria
• Protista
• Fungi
• Plants
• Animals

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Our 6 Kingdom System

• 6 kingdoms determined by
• Characteristics of cells
• How they obtain food

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