CLASSIFICATION
Finding Order In Diversity
Linnaean Taxonomy. In Wikipedia [Web]. Retrieved 03/09/2007, from http://en.wikipedia.org
Definition of Taxonomy

Discipline of classifying
organisms and
assigning each
organism a universally
accepted name
1
Leptinotarsa decemlineata
Colorado potato beetle
Why Classify?
1. To study the diversity of life, biologists use a
classification system to name organisms and
group them in a logical manner.
2. Taxonomists are able to organize organisms
into groups that have biological importance.
Why Classify?
3. Classification makes life easier. What are some
ways we classify in our daily living?
Assigning Scientific Names
1. Using common names is confusing because many
organisms may have several different common names.
2. For example, the cougar is also known as the mountain lion,
puma or catamount…thus the need for a scientific name.
Scientific name: Puma concolor
Assigning Scientific Names
3. A Swedish botanist
named Carolus Linnaeus
developed a two-word
naming system for
naming all species on
Earth.
4. This two-word naming
system is called
Binomial Nomenclature.
2
Assigning Scientific Names
5. The first part of the scientific name is the genus
name. This word is always written first with the
first letter capitalized. This name appears in italics
or is underlined.
6. The second part of the scientific name is the species
name. This word is always written second and is not
capitalized. This name also appears in italics or is
underlined.
Write the scientific name for humans:
Genus name: Homo
Species name: sapien
Homo sapien or H. sapien
Linnaeus’ System of Classification
1. Linnaeus’ hierarchical system of
classification includes seven
levels. They are, from largest to
smallest, kingdom, phylum, class,
order, family, genus, and species.
Kingdom
Phylum
Class
Order
2. In taxonomic nomenclature, each level
is called a taxon (plural: taxa) or
taxonomic category.
Family
Genus
Species
Linnaeus’ System of Classification
3. The kingdom is the largest and most inclusive (includes)
of the taxonomic categories.
4. Species is the smallest and least inclusive of the
taxonomic categories.
5. The more taxonomic categories that two organisms
share, the more closely related they are considered to be.
What do the
scientific names
of each bear tell
you about their
similarity to
each other?
Ursus arctos
Ursus maritimus
Ailuropoda
melanoleuca
Application of Linnaeus’ Classification System
Organism
Kingdom
Phylum
Class
Order
Family
Genus
Species
Cat
Animalia
Chordata
Mammalia
Carnivora
Felidae
Felis
domesticus
Wolf
Animalia
Chordata
Mammalia
Carnivora
Canidae
Canis
lupus
Fly
Animalia
Arthropoda
Insecta
Diptera
Muscidae
Musca
domestica
Application of Linnaeus’ Classification Systmem
1. What type of animal is M. domestica?
2. Which two animals listed on the table are most closely
related?
3. At what classification level does the evolutionary
relationship between cats and wolves diverge (become
different)?
Family Level
Evolutionary Classification
1. Darwin’s theories on descent with modification have led
to the study of phylogeny, which is the study of
evolutionary relationships among organisms.
2. Biologists group organisms into categories that represent
lines of evolutionary descent or phylogeny and not just
physical similarities.
3. Grouping organisms based on their evolutionary history is
called evolutionary classification.
Evolutionary Classification and Cladograms
1. Cladograms are tree-like diagrams that show the
evolutionary relationships among a group of organisms
Domain Eukarya
Domain
Archaea
Domain
Bacteria
Three Domains Cladogram
EVOLUTIONARY
CLASSIFICATION
A
B
C
D
E
F
Clade or
lineage
Speciation:formation of two
New species from one
T
I
M
E
Evolutionary Classification and Cladograms
2. Cladistic analysis identifies and considers new
characteristics that arise as lineages evolve over time.
3. Derived characters are those that appear in recent parts of
a lineage but not in its older members.
4. When a derived characteristics appears ahead of an
organism listed on a cladogram, the organism lacks that
derived characteristics.
5. When a derived characteristics appears below, beneath,
or before the organism, the organism possesses or has that
derived characteristics.
CLADOGRAM
Fish
Frog
Lizard
Mouse
Chimp
Pigeon
Hagfish
Feathers
Fur &
Mammary
Glands
Claws
or Nails
Lungs
Jaws
VENN DIAGRAMS
1. VENN Diagrams can be used to make
models of hierarchical classification
schemes. A Venn diagram is shown
below:
A.
B.
C.
D.
A.
B.
C.
•
•
•
•
D.
Four groups are represented by circular regions
Each region represents different taxonomic levels.
Regions that overlap, share common members.
Regions that do not overlap do not have common
members.
A.
B.
D.
C.
Matching:
 Mammals C
 Animals with backbones
 Insects D
 All animals A
B
Citations

1. In Wikipedia [Web]. Retrieved 03/09/2007, from http://en.wikipedia.org/wiki/Beetles

2. Carlolus Linnaeus. In Wikipedia [Web]. Retrieved 03/09/2007, from
http://en.wikipedia.org/wiki/Linnaeus