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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

Some Common Scientific Names
What are the Common Names?
Homo sapiens
 Canis lupus
 Felis domesticus

Homo Sapiens
Canis Lupus
Grey Wolf
Felis domesticus or catus
Domestic Cat
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.
–
–
–
–
–
–
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Kingdom
Phylum
Class
Order
Family
Genus
Species
Check Your Answers
Kingdom – Animalia
 Phylum – Chordata
 Class – Mammalia
 Order – Primate
 Family – Hominidae
 Genus – Homo
 Species – H. Sapiens

What is a species anyway?
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Biological species concept
– A group of actually or potentially breeding
natural groups that are reproductively
isolated from other groups.
» Ernst Mayr, 1924
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)
1. Archaebacteria
2. Eubacteria

Eukaryotes
1.
2.
3.
4.
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
Any Questions?
Let’s Classify the Domestic Cat
and The Grey Wolf
Grey Wolf
 Kingdom - Animalia
 Phylum - Chordata
 Class - Mammalia
 Order - Carnivora
 Family - Canidae
 Genus - Canis
 Species - C. Lupus
Domestic Cat
 Kingdom - Animalia
 Phylum - Chordata
 Class - Mammalia
 Order - Carnivora
 Family - Felidae
 Genus - Felis
 Species - F. Catus
Dichotomous Key
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A Dichotomous Key is a tool used in plant or animal
identification.
The dichotomous key is a series of questions, and
each question is a choice between two
characteristics.
The identity of an organism is determined through the
process of eliminating characteristics that do not
apply to it.
A Simplified Version of a Dichotomous Key
Another Simplified Dichotomous Key
Example of a Dichotomous Key used for
Determining Land Cover
Credits

step.nn.k12.va.us/science/Bio/biology_p
pt/taxonomy.ppt