Biology

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Biology

• 9.1 The Necessity of Classification

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Warm Up 01.23.07

• Explain in detail how you would classify your
  classmates into different groups if you had to.

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Why Classify?

• We normally do this for convenience
• Think of your bedroom
• Clean clothes in one place
• Dirty clothes in another place
• Books and papers in the corner
• Your bed, sheets and blankets in one place
• How confusing would it be if everything was
  everywhere?

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Taxonomy

• AKA Systematics
• This is the science of classifying animals into
  groups
• It is hard to estimate how many species there are
  in the world, but we do agree that the majority
  of species are not yet discovered
• Panama study where trees were fogged to release
  the insects living in them 80 were not yet
  discovered!

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Problems

• When an organisms is discovered, we may not know
  enough about it to accurately place it in the
  appropriate group
• Also, sometimes groups are split or expanded.
• Its not a perfect science.

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History of Taxonomy

• Aristotle attempted the first recorded
  classification of organisms into 2 groups
  plants and animals
• Each of these groups was divided into three
  categories
• Plants herbs (no woody parts), shrubs (several
  short woody stems) and trees (long woody stem)
• Animals birds, fish and animals

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Artificial Classification System

• Aristotles system was based on appearance, so we
  call it an artificial classification system
  (based on observable characteristics)
• In these cases, there are many generalizations
  (most organisms that fly are birds) or exceptions
  (birds include all flying organisms except
  butterflies, flies and bats)

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Linnaeus

• In the mid-1700s after the West Indies and
  Central America was discovered, there were so
  many new species
• Carolus Linnaeus published two books Species
  Plantarium and Systema Naturae, introducing a new
  system of classification and it was very readily
  accepted

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Linnaean System

• More flexible than previous systems
• We still use this system today
• International scientific committees meet every
  few years to review any proposed changes and
  decide whether or not they should be adopted.
• Very official system

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Todays System of Classification

• 7 Basic Levels MEMORIZE
• Kingdom
• Phylum (pl. Phyla)
• Class
• Order
• Family
• Genus (pl. Genera)
• Species

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Homework 01.23.07

• Review Questions 9A-1
• Page 242
• 1-5