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CLASSIFICATION
Sections 17.1 ,
17.2, 17.4
THE LINNAEAN SYSTEM
OF CLASSIFICATION
17.1 pg. 518
TAXONOMY
Taxonomy – science of naming and
classifying organisms.
Gives scientists a standard way to refer to species
and organize the diversity of living things.
Group of organisms = taxon
SCIENTIFIC NAMES
Binomial Nomenclature:
SCIENTIFIC NAMES
1 st name: Genus – includes one or more
physically similar species that are thought
to be closely related.
Italicized and Capitalized
2 nd name: Species descriptor – refers to a
trait of the species, scientist who
discovered it, or its native location.
Italicized and lower case
SCIENTIFIC NAMES
Examples:
Quercus alba =scientific name
for white oak
Tyto alba = scientific name for
barn owls
These two organisms share the
species name alba. Does this
mean they are closely related?
SCIENTIFIC NAMES
Advantages over common names:
1. many common names for organisms are
similar; scientific names help scientists talk
about particular species without confusion.
2. one organisms can have multiple common
names; one scientific name leads to less
confusion.
3. Different languages in different countries.
ADVANTAGES OVER COMMON NAMES
LINNAEAN CLASSIFICATION
How its organized:
Seven levels, or taxa
Most general to most specific
1. Kingdom  2. Phylum  3. Class  4. Order
 5. Family  6. Genus  7. Species
Lets make a pneumonic!
LINNAEAN CLASSIFICATION
Limitations: Focuses on physical
similarities alone; no molecular biology
(DNA) to back it up.
Are physically similar looking species
always closely related? Why/why not?
LINNAEAN CLASSIFICATION
Limitations Example:
Panda and raccoon have
similar coloring, so Linnaean
grouped them together in the
same family.
DNA evidence shows us that a
panda is more closely related
to bears than raccoons.
Red pandas are more closely
related to raccoons than to
giant pandas.
CLASSIFICATIONS
BASED ON
EVOLUTIONARY
RELATIONSHIPS
17.2 pg. 524
PHYLOGENIES
1. Defined as: evolutionary history for a
group of species.
PHYLOGENIES
2. Can be shown using diagrams called:
cladograms
3. Which are constructed by identifying:
common ancestors
Cladistics – classification on common ancestry
PHYLOGENIES
4. Can be determined
using evidence such as:
Molecular evidence –
DNA
 a cladogram before
and after molecular
evidence
CLADOGRAM
Derived Characters – how groups of species
are placed in order
shown as hash marks between branches of
cladogram
Node: represent the most recent common
ancestor shared by a clade
each place where a branch splits
Clade: “snip rule” – when you snip a branch
off under a node, a clade falls off.
CLADOGRAM
DOMAINS AND
KINGDOMS
17.4 pg. 533
WOESE’S DISCOVERY
Woese discovered two genetically different
groups of prokaryotes
This discovery split Monera into Bacteria and
Archaea.
Each group has different cell walls
RESULT: life is now divided into three domains
THREE DOMAINS
2. Bacteria – which includes kingdom Bacteria
One of the largest groups of organisms on
Earth.
THREE DOMAINS
4. Archaea – which
includes kingdom Archaea
Known for their ability to
live in extreme
environments.
THREE DOMAINS
6. Eukarya – which includes the kingdoms
Protista, Plantae, Fungi, and Animalia.
All organisms in Eukarya
are eukaryotic with a
nucleus and membrane
bound organelles.
They can be single cellular,
colonial, or multicellular.
THREE DOMAINS