Taxonomy

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Taxonomy

• Techniques of the past and present to provide
  information about an organism.

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Part OneHow it all started.
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TAXA

• Greek word - means categories or groups .
• Singular form of the term is taxon.
• Taxonomy the science that deals with the
  classification or grouping of living things.

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The first classification system

• 400 B.C. - Greek philosopher, Aristotle,
  developed a system for sorting living organisms.
• His system consisted of two kingdoms the plant
  and animal kingdoms.

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• Plants were grouped according to their stem
  structure and size. The 3 subgroups were

Trees
Shrubs
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• Animals were grouped according to habitat

Land
Water
Air
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Gradually Aristotles system showed weaknesses.
Can you identify any?

• not specific enough
• too many organisms were being discovered
• The microscope discovered many organisms that
  would not fit into Aristotles classification
  system.
• NOTE despite its weaknesses this first
  classification system was used for about 2,000
  years.
• Who improved on this old system?

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Beginnings of Modern Taxonomy

• 1600s
• John Ray - introduced a term called species.
• Stated that a species was a group of organisms
  that were
• similar in structure
• able to mate and pass the traits to their
  offspring.

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Founder of modern taxonomy

• Carolus Linnaeus (also in the 1600s)
• Also used structural similarities as the basis
  for his taxonomic system
• Started with a large group or kingdom which he
  divided into subgroups
• Organisms could be sorted more precisely

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Todays taxonomy still uses Linnaeus system

• 7 Taxa / Groups
• 1. Kingdom
• 2. Phylum
• 3. Class
• 4. Order
• 5. Family
• 6. Genus
• 7. species

• Example human
• Animalia
• Chordata
• Mammalia
• Primates
• Hominidae
• Homo
• sapiens

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Todays Modified System
8 Taxa / Groups 1. Domain 2. Kingdom 3.
Phylum 4. Class 5. Order 6. Family 7.
Genus 8. species

• Example human
• Eukaryota
• Animalia
• Chordata
• Mammalia
• Primates
• Hominidae
• Homo
• sapiens

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What Changed Three Domains added (based on
DNA) 1) Archaea extremophiles, unicellular
prokaryotes, ex.- methanogens, halophiles, and
thermoacidophiles 2) Bacteria all other
unicellular prokaryotes, Note- Kingdom Monera no
longer exists 3) Eukaryota 4 other Kingdoms
Protista, Fungi, Plantae, and Animalia.
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Duh, King Philip Came Over For Green soup
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Scientific Naming System

• There are always two Latin words to name each
  species.
• Process is called binomial nomenclature.
• Used world-wide to prevent confusion caused by
  various languages.
• Prevents confusion with common names.
• Example A puma, cougar and mountain lion are all
  the same animal. Its scientific name, world-wide
  is
• Felis concolor

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More about scientific naming

• The scientific name is composed of the Genus and
  the species.
• Rules for writing scientific names.
• Genus is given first and must be Capitalized and
  underlined (or in italics)
• Species name is second and must begin with a
  lower case letter and must be underlined (or in
  italics)
• Example Homo sapiens or Homo sapiens

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Other examples of scientific names

• Cats
• Wildcat
• Cougar
• Housecat

• Genus - Felis
• Felis sylvestris
• Felis concolor
• Felis domesticus or Felis domesticus

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Review of the key terms

• Taxa
• Taxonomy
• Latin names
• Aristotle
• John Ray
• Carolus Linnaeus
• Species

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Binomial Nomenclature

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Part TwoModern Methods
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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(phy-log-e-ny)

• The field of biology where scientists study the
  evolutionary history of living organisms.

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• Phylogenists often study fossils.

• 1. Fossil Records Fossils provide evidence that
  show how plants and animals are related by
  preserving structures that can be studied and
  compared.

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What is a fossil ?

• A cast or mold of an organism preserved in
  rock that formed where the organism died.

Fish
Trilobite
Archaeopteryx
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• A fossil may also consist of the organism
  itself preserved in ice, amber, or in volcanic
  glass.

Cockroach in amber
Can you guess what these are?
Firefly
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• A fossil may also consist of tracks
  (footprints), seeds, or skeleton preserved in
  deposits (sediments).

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2. Homologous Structures

• are parts in different animals that show
  similarities in their structure.

• Ex.- a bat wing, a human arm, a whale flipper and
  a cat foreleg are all homologous structures.

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3. Comparative Embryology

• Taxonomists study the patterns of development
• before birth. Embryos of organisms believed to
• be closely related show similar patterns of
• development.

Dolphin embryo
Human embryo
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Modern Methods (contd)

• 4. Comparative biochemistry the study of the
  chemistry of blood, enzymes and other specific
  substances produced by animals and plants.
• Example hemoglobin in the blood cells of
  gorillas and humans are the same except for one
  amino acid.
• 5. Comparing sequences of amino acids in
  organisms helps to reveal relationships.
• Q. What determines the sequence of these amino
  acids ?
• A. DNA

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Modern Methods (contd)

• 6. Comparative DNA and RNA Scientists now study
  DNA and RNA structure to see their similarities
  among organisms.
• DNA of humans and chimpanzees is 96 identical.
• DNA between humans and other mammals
  (dog,horses,whales,bats,etc) is only about 80
  identical.

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Modern Methods (contd)

• 7. Function what the organism does its place in
  the ecosystem.
• 8. Behavior series of activities performed by an
  organism in response to stimuli.
• 9. 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 educated opinions and
  as a result there are a number of ways in which
  organisms can be grouped.