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Taxonomy

Finding Order in Diversity

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Taxonomy:

Discipline of classifying organisms and giving them universally accepted names

British buzzard

(hawk)

American buzzard

(vulture)

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Why Classify?

To name organisms and to group them in a logical manner

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How to Classify?

  • Usually by structure and appearance
  • Phylogeny (tree of life) and habitat can be factors

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Assigning Scientific Names

  • Using common names is confusing because many organisms have several different common names
    • Cougar AKA mountain lion, puma, catamount
  • Scientific names

eliminate confusion

    • Cougar AKA Felis concolor

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Carolus Linnaeus

  • Carolus Linnaeus was a Swedish botanist. (He studied plants.)
  • He developed binomial nomanclature
  • Binomial Nomenclature:
              • A two word naming system

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Assigning Scientific Names

  • Genus is capitalized, species is not
  • Both words are italicized or underlined

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Homo sapien

Canis lupus

  • The first part of the scientific name is the genus.
  • The second part of the scientific name is the species.

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Assigning Scientific Names

Gnathia marleyi

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Aptostichus stephencolberti

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Aptostichus barackobamai

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Aptostichus angelinajolieae

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Aleiodes shakirae

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Litarachna lopezae

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Aegrotocatellus jaggeri

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Aleiodes falloni

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Categories of Classification

DOMAIN

KINGDOM

PHYLUM

CLASS

ORDER

FAMILY

GENUS

SPECIES

Most Broad

Most Specific

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Categories of Classification

The more taxonomic levels that two organisms share, the more closely related they are.

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Thinking Critically

Organism

Cat

Wolf

Fly

Kingdom

Animalia

Animalia

Animalia

Phylum

Chordata

Chordata

Arthropoda

Class

Mammalia

Mammalia

Insecta

Order

Carnivora

Carnivora

Diptera

Family

Felidae

Canidae

Muscidae

Genus

Felis

Canis

Musca

Species

F. domesticus

C. lupus

M. domestica

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Questions

What type of animal is Musca domestica?

    • Fly
    • Cat
    • Wolf

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Questions

Which two organisms are most closely related?

    • Fly and cat
    • Fly and wolf
    • Cat and wolf

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Questions

At which classification level does the evolutionary relationship between cats and wolves diverge?

    • Kingdom
    • Family
    • Phylum

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What do the scientific names of the polar, grizzly, and panda bears tell you about their similarity to each other?

Ursus maritimus

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Ursus arctos

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Ailuropoda melanoleuca

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What if you don’t know what an organism is?

  • One way to identify an unknown organism is to use a dichotomous key
  • Dichotomous key: an identification tool that uses pairs of contrasting descriptions
  • Each description will either identify an object or send you to another pair of descriptions

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Dichotomous Keys

Before you use a key:

  • Look over all the traits of your organism
  • Identify key features and terms
  • Try to narrow down what you’re looking at
  • Always start your search for the correct scientific name at the beginning of the key

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DICHOTOMOUS KEYS

  1. a. If it runs on gas – Go to 2

b. If it doesn’t run on gas – Walking

2. a. If it is on land – Go to 3

b. If it’s not on land – Boat

3. a. If it has four wheels – Car

b. If it has two wheels – Motorcycle

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