Systematics
Species of Organisms
●There are 13 billion
known species of
organisms
●This is only 5% of all
organisms that ever
lived!!!!!
●New organisms are still
being found and identified
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
Benefits of Classifying
●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
Historical
perspectives of
Animal Taxonomy
Pre-Linnaean Period
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.
Early Taxonomists
●John Ray, a
botanist, was
the first to
use Latin for
naming
●His names
were very
long
descriptions
telling
everything
Linnaean Period
Carolus Linnaeus 1707 –
1778
●18th century
taxonomist
●Classified
organisms by
their
structure
●Developed
naming
system still
Carolus Linnaeus
●Called the “Father of
Taxonomy”
●Developed the
modern system of
naming known as
binomial nomenclature
●Two-word name
(Genus & species)
Standardized
●Binomial Naming Turdus
nomenclature migratorius
used
●Genus species
●Latin or Greek
●Italicized in
print
●Capitalize
genus, but NOT Peacock
species Pavo cristatus
●Underline when
Binomial Nomenclature
Rules for Naming Organisms
●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
Classification Groups
●Taxon ( taxa-plural) is a
category into which related
organisms are placed
●There is a hierarchy of
groups (taxa) from broadest
to most specific
●Domain, Kingdom, Phylum,
Class, Order, Family, Genus,
species
Hierarchy-Taxonomic
Domain
Groups
BROADEST
TAXON
Kingdom
Phylum (Division – used for
plants)
Class
Order
Family
Genus
Species
Domains
●Broadest, most inclusive
taxon
●Three domains
●Archaea and Eubacteria are
unicellular prokaryotes (no
nucleus or membrane-bound
organelles)
●Eukarya are more complex
and have a nucleus and
membrane-bound organelles
Concept of Five Kingdom Classification
R. H. Whittaker (1969)
Proposed Five Kingdoms:
Monera (Prokaryotes – bacteria,
cyanobacteria)
Protista (unicellular eukaryotes –
amoeba, algae)
Fungi (molds, mushrooms, yeasts)
Plantae (plants)
Animalia (animals)
Taxons
●Most genera contain a
number of similar
species, with the
exception of Homo that
only contains modern
humans
●Classification is based
on evolutionary
relationships
Post-Linnaean Period
Jean-Baptiste Lamarck (1744–1829)
Proposed organisms evolve over time.
Influenced classification by evolutionary ideas
Charles Darwin (1809–1882)
Theory of Natural Selection.
Emphasized that classification should reflect
common ancestry.
Ernst Haeckel (1834–1919)
Proposed a new kingdom Protista for unicellular
organisms.
Emphasized evolutionary trees (phylogeny).
Basis for Modern
Taxonomy
●Homologous structures
(same structure, different
function)
●Similar embryo
development
●Similarity in DNA, RNA,
or amino acid sequence of
Proteins
Homologous Structures show Similarities in
Similarities in Vertebrate
Embryos
Cladogram
Diagram showing how organisms are
related based on shared, derived
characteristics such as feathers, hair, or
scales
Primate
Cladogram
Dichotomous Keying
●Used to identify
organisms
●Characteristics given in
pairs
●Read both
characteristics and either
go to another set of
characteristics OR
identify the organism
Example of Dichotomous
1a Tentacles present Key
– Go to 2
1b Tentacles absent – Go to 3
2a Eight Tentacles – Octopus
2b More than 8 tentacles – 3
3a Tentacles hang down – go
to 4
3b Tentacles upright–Sea
Anemone
4a Balloon-shaped body–
Jellyfish
4b Body NOT balloon-shaped -
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