Classification of Organisms

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Classification of Organisms
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• Taxonomy
• Science of describing, naming, and classifying
  organisms
• Taxon
• Any particular group within a taxonomic system

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Aristotles system

• Aristotle (384-322 B.C.)
• Greek philosopher
• Animals
• Habitat (land, water, or air)
• Physical characteristics
• Plants
• Herbs, shrubs, or trees
• Depends on their stems

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Shortcomings of system

• Some animals lived on land and in water
• Did not show evolutionary history
• Birds, bats, and flying insects were grouped
  together because they all can fly

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Linnaean System

• Carolus Linnaeus (1707 1778)
• Swedish botanist
• Linnaean system
• Based on form and structure

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Levels of Classification

• Domain
• Kingdom
• Phylum/Division
• Class
• Order
• Family
• Genus
• Species

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Domain

• Contains one or more kingdoms

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Kingdom

• Taxon of similar phyla or divisions

Animalia
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Phylum/Division

• A taxon of similar classes
• Phylum Animals
• Division Plants

Chordata
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Class

• A taxon of related orders

Mammalia
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Order

• A taxon of related families

Carnivora
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Family

• A group of related genera (sing. genus)

Felidae
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Genus

• Group of similar species

Panthera
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Species

• Specific epithet
• Describes a characteristic of the organism

tigris
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Binomial nomenclature

• Developed by Linnaus
• Two names
• Genus
• Group of similar species
• Species (specific epithet)
• Descriptive name
• Ex. Genus species or Genus species
• Homo sapiens or Homo sapiens
• Also called the scientific name

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Phylogenetic classificaion

• Phylogenetics
• Analysis of the evolutionary or ancestral
  relationships among taxa

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Evidence of Shared Ancestry

• Structural similarities
• Breeding behavior
• Geographical distribution
• Chromosome comparisons
• Biochemistry

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Cladistics

• Uses shared and derived characters as criteria
  for grouping taxa
• Shared character
• Feature that all members of a group have in
  common (hair in mammals)
• Derived character
• Feature that evolved only within the group
  (feather in birds)

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Cladogram
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Molecular cladistics

• Branch lengths are proportional to the number of
  amino acid changes
• See pg 344 of text
• Analyzing karyotypes
• If two species have the same banding patterns in
  regions of similar chromosomes
• Regions likely have been inherited from a single
  chromosome in the last common ancestor of the two
  species

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The Three Domains
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Domain Bacteria

• Small, single-celled prokaryotic organisms
• Have cell wall and reproduce by cellular fission

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Domain Archae

• Prokaryotes
• Has cell membrane
• Some are autotrophic and chemosynthetic
• Many inhabit harsh environments (deep sea thermal
  vents, salty lakes, intestines of some animals

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Domain Eukarya

• All eukaryotic organisms
• Large cells with true nucleus and complex
  cellular organelles
• Plants, animals, fungi, other single-celled
  organisms.

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The Six Kingdoms
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Eubacteria

• True bacteria
• Microscopic, unicellular
• Have strong cell walls
• Live in most habitats except extreme ones

Cyanobacteria
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Archaebacteria

• Ancient bacteria
• Microscopic, unicellular
• Live in extreme environments, like hydrothermal
  vents

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Protists

• Eukaryote that are not plants or animals, or
  fungi very diverse
• Include all microorganisms that are not bacteria
• Ex. Algae and slime molds

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Fungi

• Eukaryotic, heterotrophic
• Unicellular or multicellular
• Absorb nutrients from organic materials in the
  environment
• Mushrooms, mildews, molds

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Plants

• Multicellular, photosynthetic eukaryotes
• Autotrophic
• Most live on land

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Animals

• Eukaryotic
• Multicellular consumers
• Heterotrophs
• Symmetrical body organization

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Dichotomous Key

• A device used for easily and quickly identifying
  an unknown organism.
• Couplets
• two statements based on characteristics of the
  organism
• By always taking the correct choice, the name of
  the organism will be revealed.

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Vertebrate Key