Unit 7: Evolution &
Classification
Ch 14 (Classification)
•How and why are organisms classified?
•What tools do we use to classify organisms?
Classification
• Taxonomy = branch of biology that deals w/
naming & classifying organisms.
• Why do we classify???
Early Classification
• First classification system
– Aristotle (Greek philosopher)
• >2000 years ago divided organisms into 2 groups
– 1. Plants
» classified by type of stem
– 2. Animals
» divided by environment (land, water, or air)
According to Aristotle
which of these 3 animals
would be classified more
closely?
How Do We Classify?
• Based on work
of Carolus
Linnaeus
–“Father of
Modern
Taxonomy”
How Do We Classify?
• Current system reflects relationships based on
phylogeny (evolutionary ancestry)
– Uses homologies to group species into larger, more
generalized categories
• According to this
who are humans
closely related to?
phylogenetic tree
most
Linnaeus’ System
• Binomial nomenclature: Two
name system that is unique to
every type of organism
Linnaeus’ System
– Names are Italicized or underlined
– written as Genus species
• Genus = 1st name, capitalized
• species = 2nd name, lower case &
descriptive
Linnaeus’ System
• All names are in Latin
• Why not common names?
Examples of names
Common name
1. Humans
2. Housefly
3. White Oak tree
4. Red Oak tree
Genus & species
1. Homo sapiens
2. Musca domesticus
3. Quercus alba
4. Quercus rubra
Levels of Classification
•
•
•
•
•
•
•
•
Did
King
Phillip
Come
Over
From
Germany
Sunday?
 Domain
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 species
Domain
Eukaryota
Where would Domain belong
in this diagram?
Levels of Classification
• What is the
relationship
among the levels?
– More closely
related  share
more levels
– From Domain
down each level
has a new set of
criteria that must
be shared
DOMAIN
Eukaryota
Once an organism shares a more specific
taxon it MUST share the more unifying taxa
How many levels of
classification do we
share with dolphins?
What is a species?
• Group of
organisms
capable of
mating with
one another
in nature to
produce
fertile
offspring
The 3 Domains
3 domains
Archaea
Eubacteria
Eukaryota
Oldest
prokaryotes that
evolved from
Archaea
(no nucleus)
Eukaryotes (cells
with a nucleus)
prokaryotes
(no nucleus)
Kingdom Monera
(older, less complex
bacteria)
Kingdom Monera
(more complex,
modern bacteria)
Kingdoms 
Plantae, Animalia,
Fungi, Protista
Domain: Archaea
• Prokaryotes
– Older, less complex group of bacteria
• live in extreme environments
– hydrothermal vents, salty or acidic environments
Domain: Eubacteria
• Prokaryotic
– Modern, more complex bacteria
• Evolved from Archaea
– Most common & very diverse, heterotrophic or
autotrophic, free-living or pathogenic
cyanobacteria
Staphylococcus
If Using the 5 Kingdom System
Instead of the 3 Domain System
• Eubacteria + Archaea Domains
together make up 1 of the 5 Kingdoms
 Monera
Domain: Eukaryota
• All are eukaryotic
–have a nucleus
• 4 of the 5 kingdoms
–1. Protista
–2. Fungi
–3. Plantae
–4. Animalia
Domain: Eukaryota
1. Kingdom Protista: mostly unicellular
organisms that are plant-like, animal-like,
or fungus-like
Amoeba
Euglena
Paramecium
Diatoms
Domain: Eukaryota
2. Kingdom Fungi: all types of fungus
(mushrooms & molds)
– Multicellular heterotrophs with cell walls of
chitin ( yeast – unicellular)
• Digest food outside the organism & then absorb
nutrients
Domain: Eukaryota
3. Kingdom Plantae: Multicellular
autotrophs with cells walls of cellulose
– Land-based plants, trees, grasses, moss, and
shrubs
• photosynthetic
Domain: Eukaryota
4. Kingdom Animalia: multicellular heterotrophs
without cell walls.
–divided into invertebrates and …………..
………. vertebrates