Classification of Organisms

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Classification of Organisms

• Chapter 17

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Biodiversity

• The variety of organisms considered at all levels
  of populations to ecosystems.
• Biologists have classified almost 2 million
  species
• More remain unidentified

www2.warwick.ac.uk/ about/environment/faqs/
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Taxonomy

• The science of describing, naming, and
  classifying organisms
• A particular group within a taxonomic system is
  called a taxon

www.schenectady.k12.ny.us/.../ Taxonomy.html
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Taxonomy continued

• Aristotle classified organisms into 2 groups
  plants or animals.
• This was inadequate because more and more
  organisms are found and described.

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The Linnaean System

• The system of grouping organisms into
  hierarchical categories according to their form
  and structure.
• Each category represents a level or grouping from
  larger, more general categories to smaller, more
  specific categories.

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Levels of Classification

• Modern version of Linnaeuss system uses 8
  levels (see page 338)
• 1. Domain
• 2. Kingdom
• 3. Phylum
• 4. Class
• 5. Order
• 6. Family
• 7. Genus
• 8. Species

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Binomial Nomenclature

• System of two-part names. The genus name
  followed by the species identifier.
• The species name is written in Italics with the
  genus name capitalized
• Species names generally come from Latin roots
• Subspecies variations of a species that live in
  different geographic areas

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Binomial Nomenclature(examples)

• Homo sapiens
• Chaos chaos
• The species name or scientific name is written in
  italics with the genus name capitalized

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Systematics

• Modern biologists use this to classify organisms
  not only by visible similarities, but also
  similarities in embryos, chromosomes, proteins,
  and DNA. The goal is to classify organisms in
  terms of their natural relationships

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Phylogenetics

• The analysis of the evolutionary or ancestral
  relationships among taxa.
• Systematists usually use several types of
  evidence to hypothesize about polygenetics.
• Use phylogenetic diagram

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Cladistics

• A system of phylogenetic analysis that used
  shared and derived characters as the only
  criteria for grouping taxa

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Three Domains of Life
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Three Domains of Life
Domain Bacteria Domain Archaea Domain Eukarya
Small, single-celled prokaryotic organisms Prokaryotes, live in harsh places, has distinctive cell membranes Eukaryotic organisms, large cells with true nucleus and complex organelles
Ex. Cyanobacteria Hetrotrophic bacteria Ex. Halophiles and Thermophiles Ex. Everything else plants, animals, etc.
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Six Kingdoms

• Eubacteria
• Arachaebacteria
• Protista
• Fungi
• Plantae
• Animalia

See page 349