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Taxonomy
The science of naming
organisms.
Aristotle
Plant or animal?
 If an animal, does it

– Fly
– Swim
– Crawl
Simple classifications
 Used common names

Carolus Linnaeus
Described organisms with two word
names, instead of polynomials
 Developed binomial nomenclature
 First word = genus name
 Second word = species name

Why binomial nomenclature?
Much easier than a 10+ word name
under old “polynomial system”
 Same name no matter where you go
 Less confusion
 Binomial = SCIENTIFIC NAME

Scientific Names You Need to
Know
Homo sapiens
 Canis lupus
 Felis domesticus
 Pan pan

Taxonomic hierarchy

Names organisms and their
relationships from very broad to very
specific
All organisms classified in a
hierarchy
Kingdom (broadest)
 Phylum
 Class
 Order
 Family
 Genus
 Species (most specific)

Notes assignment:

Look up the classification for humans
for all seven hierarchies and write them
below.
What is a species anyway?

Biological species concept
– A group of actually or potentially breeding
natural groups that are reproductively
isolated from other groups.
» Ernst Mayr, 1924

BSC’s problems
– Hybrids
• Sterile offspring of two different species
– Asexual organisms
How many are out there?

Scientists currently estimate that
– There are 10 million species worldwide
– Over 5 million live in the tropics
– Most unnamed species are small or
microscopic
Why is taxonomy useful?
Helps prevent confusion among
scientists
 Helps to show how organisms are
related
 Can be used to reconstruct
phylogenies – evolutionary histories –
of an organism or group

A note on cladograms
Graph showing when different groups
diverged from a common ancestral line
 Points where they diverge are often
noted with a feature that was different
between ancestral group and a “new”
feature in the group that split off.

Bird Cladogram
The 6 kingdoms

Prokaryotes (Used to be 1 kingdom,
Monera)
– Archaebacteria
– Eubacteria

Eukaryotes
– Fungi
– Protista
– Animal
– Plantae
Overview of the 6 kingdoms

Archaebacteria
– Unicellular
– Live in extreme environments
– Prokaryotic

Eubacteria
– Unicellular
– Prokaryotic
– “Common bacteria”
Overview of the 6 kingdoms

Protista
– Eukaryotic
– Unicellular or colonial
– Lots of different life styles

Fungi
– Cell walls made of chitin
– Eukaryotic
– Multicellular
– External heterotrophs
Overview of the 6 kingdoms

Plantae
– Eukaryotic & Multicellular
– Cell walls made of cellulose
– Autotrophic

Animalia
– Eukaryotic & Multicellular
– No cell walls
– Internal heterotrophs