Taxonomy
Classification
 Classification
- the grouping of objects or
information based on similarities.
 Used
to better understand and study the
enormous variety of living things.
Taxonomy
Taxonomy-The
branch of
biology that groups and names
organisms based on studies of
their different characteristics.
Classification
 Based
on a system developed by Carolus
Linnaeus.
 He established a system of groups called
Taxa (Taxons)
 He ranked taxa from the largest, most
general groups to the smallest, most
specific groups.
Classifying Living Organisms
 Organisms
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KingPhilipCameOver For GoodSpaghetti-
are grouped into taxon
Kingdom
Phylum
Class
Order
Family
Genus
Species
Classifying Living Organisms
 At
each level, organisms that share the
most characteristics are grouped.
 Species is the most specific. (members
of the same species can produce
offspring.)
 Kingdom - is the most general.
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NOTE: THE PLANT KINGDOM IS DIVIDED INTO DIVISIONS
INSTEAD OF PHYLA.
Linnaeus’s System
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Carolus Linnaeus’ classification system:
in 18th century
Divided organisms into 2 groups: plants
& animals
Placed plants & animals into groups
based on similarities of form (shape,
structure)
Linnaeus’s System
 Has
groups within larger groups within still
larger groups
 Uses unique (one-of-a-kind), descriptive
Latin names as scientific names for each
organism
• Bats fly like birds, but have hair and
produce milk

Therefore bats are mammals and not birds
Binomial Nomenclature
Crayfish, Mudbug  What
is the difference?
 Crawdad,
 Scientists
need a universal name for
every organism.
 He proposed a system of naming
using 2 names; this system is called
Binomial nomenclature
 The
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2 names for each organism are:
Genus - always first and capitalized; can be
abbreviated to 1 letter.
species - second and lowercase
****Both are underlined or italicized***
 Humans- Homo sapiens

Homo- Genus sapiens- “Wise”
Domain
1.
2.
3.
Archae
Eubacteria
Eukarya
Six Kingdom Taxonomy System
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How evolutionary relationships are determined:
Today the most generally accepted classification
system contains six kingdoms:
Archaebacteria
Eubacteria
Protists
Fungi
Plants
Animals
Six Kingdoms
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These kingdoms are then broken down into
smaller categories.
 Characteristics that scientists use to classify
the relationships of organisms include:
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structural similarities
breeding behavior
geographical distribution
chromosome comparison
biochemistry
Dichotomous Key

Dichotomous Key: made of sets of
numbered statements; each set deals
with 1 trait of the organism; follow the
numbered sets until the key reveals the
name of the organism.
Classification Models
 Phylogeny-
The evolutionary history of a
species.

Also shows evolutionary relationships of
species
Cladistics
 Cladistics:
system of classification based
on phylogeny (evolutionary history of a
species)
Cladogram
 Cladogram:
branching diagram that
models the phylogeny of a species,
resembles a pedigree or family tree
showing proposed ancestry of the species.
Cladogram Example
 1. What five probable ancestors of the
modern bird (robin) are shown on the
cladogram?
Answer to #1
•Archaeopteryx
•Velociraptor
•Sinornis
•Allosaurus
•Theropods
 2.
Which dinosaur is probably the most
recent common ancestor of Velociraptor
and Archaeopteryx?
Answer to #2:
Sinornis
 3.
Which traits shown on the cladogram
are shared by Archaeopteryx and modern
birds?
Answer to #3
Light bones, 3-toed
foot, Wishbone,
down feathers, and
feathers with shaft,
veins, and barbs
Phylogenetic Diagram
Fan-like model can show time organism
became extinct, or the relative number of
species in a group (evolutionary history)
 1.
How does the fanlike diagram differ
from a cladogram?
Answer to #1
Cladograms provide phylogenetic
relationships among species.
Fanlike diagrams communicate the time
organisms became extinct or the relative
number of species in a group.
 2.
To which group are sea stars more
closely related, arthropods or jellyfishes?
Answer to #2
arthropods
 3.
Which group of animals includes the
fewest species?
Answer to #3
Sea Stars
(Echinoderms)
Question
 As
scientists began to learn more about
geologic time, they incorporated their
findings in their systems of classification.
The new system that accounted for an
organism’s evolutionary history is called-
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A. Binomial nomenclature
 B. Phylogeny
 C. Taxonomy
 D. None of the above
B. phylogeny
Question
 What
does a fanlike diagram show that a
cladogram does not?
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A.
B.
C.
D.
Phylogenetic relationships
Relative number of species in each group
Anatomical features of each species
Mode of extinction
B. Relative number of species in each group