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CLASSIFICATION
Why do you think scientists like to
put organisms into groups, like
mammals or insects?
WHAT IS CLASSIFICATION?
 Classification
is the arrangement
of organisms into orderly groups
based on their similarities
 Classification is also known as
taxonomy
 Taxonomists are scientists that
identify & name organisms
 Taxonomists classify organisms
into groups called taxon
WHY CLASSIFY?
 Scientists
have classified about 2 million
species
 However, there are many more
organisms than we have found.
 Estimates usually range from 3-10
million, but go as high as 50 million
 That shows Earth has a tremendous
amount of biodiversity(variety of
organisms)
 This is only 1-5% of all organisms that
have ever lived!!!!!
WHY CLASSIFY?
 Accurately
& uniformly names organisms
 Prevents misnomers such as starfish &
jellyfish that aren't really fish
 Uses same language (Latin or some
Greek) for all names
Sea “horse”??
CONFUSION IN USING DIFFERENT
LANGUAGES FOR NAMES
LATIN NAMES ARE UNDERSTOOD BY ALL
TAXONOMISTS
EARLY TAXONOMISTS
 2000
years ago, Aristotle was the first
taxonomist
 Aristotle divided organisms into plants
& animals
 He subdivided them by their habitat --land, sea, or air dwellers
CAROLUS LINNAEUS: 1707 –1778
 18th
century
taxonomist
 Classified
organisms by
their structure
 Developed
naming
system still
used today
CAROLUS LINNAEUS
Called
the “Father of
Taxonomy”
 Developed the modern
system of naming known as
binomial nomenclature
Two-word naming system
BINOMIAL NOMENCLATURE
 Genus




species
Latin or Greek
Capitalize
genus, but NOT
species
Underline when
writing
Italicized in
print
American Robin
BINOMIAL NOMENCLATURE
The International Code for Binomial
Nomenclature contains the rules for naming
organisms
 All names must be approved by International
Naming Congresses (International Zoological
Congress)
 This prevents duplicated names
 Organisms are often named using descriptive
words, like habitat or a physical characteristic
OR sometimes using the person whom discovered
them

LEVELS OF CLASSIFICATION
The
levels of classification are a
hierarchy of groups (taxa) from
broadest (domain) to most
specific (species)
LEVELS OF CLASSIFICATION
 Domain
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
 Sometimes
subspecies is
added to the
bottom of the list
 Subspecies are
the same
species, but they
live in different
areas
 King
 Phillip
 Came
 Over
 For
 Good
 Soup!
SYSTEMATICS
 Systematics
is a science whose goal is to
classify organisms in terms of their
natural relationships
 Phylogenetics is a type of systematics
PHYLOGENETICS
 The
analysis of the evolutionary or
ancestral relationships among taxa.
 Classification is based on
evolutionary relationships
 Found by studying RNA, DNA,
amino acids, homologous
structures, and embryos
 These relationships are often shown
in a cladogram
CLADISTICS
 Cladisticsis
a type of phylogenetics
 A cladogram is a type of phylogenetic
diagram
CLADISTICS

Cladogram-A diagram showing how organisms
are related based on shared, derived
characteristics such as feathers, hair, or scales
 Shared characters are features that ALL
members of a group have in common.
 For example, all organisms in the Domain
Eukarya domain have true nuclei
 Derived characters are features that
evolved only in the group under consideration.
 Feathers for example, are believed to have
evolved only in the birds, not from a common
ancestor that they have with reptiles.
CLADISTICS
 Cladograms
are organized into clades,
which is an ancestor and all of its
descendants.
 Cladograms are not only based on
physical features, they are also based on
biomolecular similarities (like DNA,
chromosomes and proteins)
 Outgroups-have no shared
characteristics with the other organisms
in the diagram and are only distantly
related
CLADOGRAM
Feathers are a
derived
characteristic in
the birds
 Hagfish are the
outgroup
 Jaws are a shared
characteristic
between all
organisms except
the hagfish

CLADOGRAM

Hair is a derived characteristic in leopards (on
this cladogram, only leopards have hair)


NOTE-hair is a shared characteristic in the previous
cladogram, so these characteristics can change based
on the cladogram
Character tables may help you make cladograms
DICHOTOMOUS KEYS
 Used
to identify organisms
 "Dichotomous" means "divided into
two parts".
 Characteristics given in pairs
 Read both characteristics and either
go to another set of characteristics
OR identify the organism
DICHOTOMOUS KEYS





Always read both choices, even if the first seems to be
the logical one at first.
Be sure you understand the meaning of the terms
involved. Do Not Guess.
When measurements are given, use a calibrated scale.
Do Not Guess.
Since living things are always somewhat variable, do
not base your conclusion on a single observation.
Study several specimens to be sure your specimen is
typical.
If the choice is not clear, for whatever reason, try both
divisions. If you end up with two possible answers,
read descriptions of the two choices to help you decide
DICHOTOMOUS KEYS
1. a. Bean round………..Garbanzo bean
b. Bean elliptical or oblong…..Go to 2
2. a. Bean white…………White northern
b. Bean has dark pigments……Go to 3
3. a. Bean solid in color…….Go to 4
b. Bean is spotted……..….Pinto bean
4. a. Bean black…………........Black bean
b. Bean reddish-brown…….Kidney
bean
MAKING DICHOTOMOUS KEYS
Eliminate
an organism in every
step (one part leads to a name,
the other part leads to another
step)
Use measurements rather than
terms like "large" and "small".
Try to make the choice a positive
one -something "is" instead of "is
not".
MAKING DICHOTOMOUS KEYS - CONTINUED
If
possible, start both choices of
a pair with the same word.
If possible, start different pairs
of choices with different words.
Precede the descriptive terms
with the name of the part to
which they apply.(like legs are
red instead of red legs)
DICHOTOMOUS KEY ASSIGNMENT
 You
will be creating your own
dichotomous key
 The subjects of the key will be all the
people in your row of desks
 Criteria must be high school
appropriate and non-insulting
 Everyone should have between 7 –
10 people