MODERN TAXONOMY

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MODERN TAXONOMY

• Techniques that are used today to provide
  information about an organism.

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Today most scientists .

• recognize that organisms have changed over time.
• accept evolution as the basis for classification.

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Phylogeny

• This is a field of biology where scientists study
  the evolutionary history of living organisms.
  Phylogenists often study fossils.

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What is a fossil ?

• A fossil is a cast or mold of an organism
  preserved in rock that formed where the organism
  died.
• A fossil could also consist of the organism
  itself in ice, amber, or in volcanic glass.
• A fossil could also consist of tracks
  (footprints), seeds, or skeleton preserved in
  deposits.

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Methods and Techniques used by todays
taxonomists.

• 1. Fossil Records Fossils provide evidence that
  show how plants and animals are related by
  preserving structures that can be studied and
  compared.
• 2. Homologous structures Homologous structures
  are parts in different animals that show
  similarities in their structure. (Please turn to
  page 475 of your text for example)

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Methods and Techniques used by todays
taxonomists. (contd)

• 3. Comparative embryology Taxonomists study the
  patterns of development before birth. Embryos of
  organisms believed to be closely related show
  similar patterns of development. (see page 477 in
  your text)

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Methods and Techniques used by todays
taxonomists. (contd)

• 4. Comparative biochemistry Taxonomists today
  now study the chemistry of blood, enzymes and
  other specific substances produced by animals and
  plants. Example -The hemoglobins in the blood
  cells of gorillas and humans are the same except
  for one amino acid.
  
• Much research today focuses on comparing
  sequences of amino acids in organisms to reveal
  relationships. What determines the sequence of
  these amino acids ?
• DNA

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Methods and Techniques used by todays
taxonomists. (contd)

• 5. Comparative DNA and RNA Scientists now study
  DNA and RNA structure to see their similarities
  amoung organisms. We know that the DNA of humans
  and chimpanzees is 99 identical. We also know
  that the DNA between humans and other mammals
  (dog,horses,whales,bats,etc) is only about 80
  identical.

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Methods and Techniques used by todays
taxonomists. (contd)

• 6. Function what the organism does, place in the
  ecosystem.
• 7. Behavior series of activities performed by an
  organism in response to stimuli.
• 8. Nutrition what an organism eats

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Final Thoughts

• It is important to recognize that a taxonomic
  classification system is not a fact.
  Classification is based on opinions and as a
  result there are a number of ways in which
  organisms can be grouped.