Transcript Classification

Classification
Why Classify?
– To study the great diversity of organisms,
biologists must give each organism a name.
– Biologists must also attempt to organize
living things into groups that have biological
meaning.
Assigning Scientific Names
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History
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18th century scientists recognized problem with
naming organisms by their common names
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cougar, puma, panther, mountain lion
UK: buzzard hawk, US: buzzard vulture
Why all the weird names?
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18th century scientists understood Latin
and Greek
Early efforts at naming organisms
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1st attempts at naming organisms often
described physical characteristics
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PROBLEMS
• some names were 20 words long
• Different scientists described different
characteristics
Binomial Nomenclature
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(Carolus Linnaeus ~ Swedish botanist)
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Two word naming system
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1st word is capitalized, 2nd is lowercased and italicized
1st part GENUS / 2nd part special character or
location
Linnaeus’s System of
Classification
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Taxonomy  taxonomic levels or taxon (taxa:
plural)
Seven levels:
Kingdom
Phylum
Class
Order
Family
Genus
Species
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Kingdom ~ King
Phylum ~ Phillip
Class ~ Came
Order ~ Over
Family ~ For
Genus ~ Great
Species ~ Soup
Grizzly bear (Ursus arctos)
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Genus: Ursus  group of closely related species
Contains 5 other kinds of bear including Ursus
maritimus.
• 2nd part: arctos / maritimus  is unique to species
within genus (important trait or indication of where
the organism lives ~ maritimus: sea)
Giant Panda differs enough to be placed in its own
genus
• Ailuropoda
Grizzly bear (Ursus arctos)
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Genera that share many characteristics, such as Ursus &
Ailuropoda, are grouped into families ~ (Ursidae)
These bears together with 6 other families of meat-eating
animals, (dogs: canidae and cats: felidae are in order
Carnivora.
Carnivora is grouped into class mammalian (wormblooded, body hair, milk) which also includes order
primates (humans, apes, monkeys, prosimians)
Class mammalian is grouped with birds (aves), reptiles,
amphibians, and all fish into a phylum: Chordata.
Taxonomy
Linnaeus only named two kingdoms
(plants & animals)
Modern Evolutionary Classification
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Problems with traditional classification
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Dolphins fish or mammals
Barnacle, limpet, crab
Because of convergent evolution,
sometimes organisms that are very different
evolve similar body structures
Evolutionary Classification
• Darwin’s theory of evolution changed the
entire way that biologist thought about
classification
• scientists began to understand that
organisms share certain traits because of
their evolutionary history
• Biologists group organisms into categories
that represent lines of evolutionary
descent, not just physical similarities.