TAXONOMY: History and Development
Dr. Pranab Debnath
Assistant Professor
Agril. Entomology
• Taxonomy : The science of describing,
naming, and classifying organisms, based
on their similarities and differences.
• Classification : Biological classification is
the process by which scientists group living
organisms. Organisms are classified based
on how similar they are.
•Historically, similarity was determined by
examining the physical characteristics of an
organism but modern classification uses a
variety of techniques including genetic
analysis.
C
D
A B
• Taxonomy : The science of describing,
naming, and classifying organisms, based on
their similarities and differences.
• Classification the grouping of
organismbased on similarities.
Monarch Butterfly (female) Lime Butterfly Cabbage butterfly
Pea blue butterfly
•There are at least 50 common names for
the animal shown on the previous 6 slides.
•Common names vary according to region.
•Soooo……why use a scientific name?
Monarch Butterfly (female), Lime Butterfly Cabbage butterfly;
Danaus plexippus Papilio demoleus Pieris rapae
Pea blue butterfly,
Lampides boeticus
Binomial Nomenclature
•a two name system for writing scientific names.
•The genus name is written first (always Capitalized).
•The species name is written second (never capitalized).
•Both words are
italicized if typed or underlined if hand written.
Example: Apis mellifera or A. mellifera
Which is the genus? The species?
"Formal" scientific names should have a third
part, the authority.
The authority is not italicized or underlined.
The authority is written as an abbreviation of
the last name of the person responsible for
naming the organism. Since Carolus Linnaeus
was the first person to name many plants, the L.
for Linnaeus is very common in plant scientific
names.
An example is Quercus alba L.
Systematics, the study of the kinds
and diversity of organisms and the
relationships among them.
taxonomy vs systematics
Systematics deal with the evolutionary
relationships between
organisms. Systematists try to determine which
organisms share a recent ancestry with
others. Systematists are concerned about the
amount of evolutionary changes that may have
occurred between ancestries.
Taxonomy deals with classifying and naming
organisms.
Classification and Identification
• Classification: Placing organisms in groups of
related species. Lists of characteristics of
known organisms.
• Identification: Matching characteristics of an
“unknown” organism to lists of known
organisms.
– Clinical lab identification
Early System of Classification
• Taxonomy is the branch of
biology that names and groups
organisms according to their
characteristics and evolutionary
history.
• Organisms were first classified
more than 2,000 years ago by the
Greek philosopher Aristotle.
Early System of Classification
• Organism’s were grouped into land dwellers, water
dwellers, and air dwellers.
• Plants were placed into three categories based on
the differences in their stems.
• As new organism’s were discovered, his system
became inadequate.
– Categories were not specific enough.
– Common names did not describe a species
accurately.
– Names were long and hard to remember.
Modern System:Hierarchy
Seven Levels of Organization
• Carolus Linnaeus (mid-1700’)s was
a Swedish biologist who
established a simple system for
classifying and naming organisms.
• He developed a Hierarchy (a
ranking system) for classifying
organisms that is the Basis for
Modern Taxonomy.
• For this reason, he is considered to
be “father” of modern taxonomy.
Modern System a Nested Hierarchy-Seven Levels
of Organization
• Linnaeus used an organisms morphology (form and
structure), to categorize it.
• His system is still being used today.
• His system allowed organisms to be grouped with
similar organisms.
• He first divided all organisms into two Kingdoms,
Plantae (Plants) AND Animalia (animals).
• This was the same as Aristotle’s main categories.
Modern System a Nested Hierarchy-Seven Levels
of Organization
• Modern System:
– Each kingdom (plant and animal) was divided into a
phylum* (division for plants)
– Each phylum into a smaller groups called class.
– Each class was divided into an order.
– Each order was divided into family (families).
– Each family was divided into a genus (plural-genera)
– Each genus was divided into a species. (scientific name)
*Note: Phyla and family were not in Linnaeus’s classification system but were added by
modern scientists.
Categories within Kingdoms
Kingdoms are divided into groups called phyla
Phyla are subdivided into classes
Classes are subdivided into orders
Orders are subdivided into families
Families are divided into genera
Genera contain closely related species
Species is unique
Levels of Classification
• Remember: King Philip Came Over For
Grandma’s Soup.
Kingdom
Phylum
Class
Order
Family
Genus
Species
SPECIES
• A species can be defined as a group of
organisms that can breed with each other to
produce another generation of similar
creatures.
• which all look more or less alike
Bufo americanus
Thank You
