Chapter 5
Section 5.1
Classification of Species
Taxonomic Systems
• Taxonomy – is the science of classification
according to the relationships among organisms.
• Scientists who carry out this work are called
taxonomists.
• Biological classification systems have two main
purposes: identifying organisms and providing a
basis for recognizing natural groupings of living
things.
Carl Linnaeus
• Our present biological classification system was
developed by a Swedish botanist named Carl Linnaeus.
• His system was based on an organism’s physical and
structural features, and operated on the idea that the
more features organisms have in common, the closer the
relationships.
• http://www.youtube.com/watch?v=Gb_IOSzLgk&feature=PlayList&p=9CEBD552C8449C39&inde
x=0
Levels of Classification
• In our present classification system, there are seven main levels or
taxa (categories used to classify organisms).
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kings play chess on fancy granite stone.
Binomial Nomenclature
• Linnaeus created rules for assigning names to plants
and animals.
• He was the first to use binomial nomeclature, which
assigns each organism a two-part scientific name using
Latin words.
• Binomial Nomenclature – a method of naming
organisms by using two names – the genus name and
the species name.
• Scientific names are always italicized.
• The first part of the scientific name is the genus and the second part is
the species.
Beaver  Castor canadensis
(genus) (species)
• The two name system also indicates similarities in evolutionary
ancestry.
• Similar organisms are grouped into the same genus.
North American Black Bear  Ursus americanus
Grizzly Bear  Ursus horribilis
Alaskan Brown Bear  Ursus arctos
Polar Bear  Ursus maritimus
Levels of classification
Dandelion
Housefly
Human
Kingdom
Plantae
Animalia
Animalia
Phylum
Tracheophyta
Arthropoda
Chordata
Class
Angiospermae
Insecta
Mammalia
Order
Asterates
Diptera
Primates
Family
Compositae
Muscidae
Hominidae
Genus
Taraxacum
Musca
Homo
Species
officinale
domestica
sapiens
5 Kingdom Classification Systems
• Originally, the kingdom level consisted of only two kingdoms: plants
(plantae) and animals (animalia).
• Later single-celled organisms that displayed both plant and animal
characteristics were discovered and a third kingdom called Protista
was introduced.
• However, shortly after it was found that some organisms within the
protista group lacked a nucleus.
• This distinction resulted in a fourth kingdom called Monera.
• Even later still, taxonomists decided that organisms like mushrooms
and moulds were distinctly different from plants and the final
kingdom was born, Fungi.
• This classification systems consists of: Animalia, Plantae, Protista,
Monera and Fungi
6 Kingdom Classification System
1.
2.
3.
4.
5.
6.
Eubacteria
Archaebacteria
Protista
Fungi
Plantae
Animalia
**Refer to Handout**
3 Domain System
•
While the 6 kingdom system grows in popularity among biologists,
many microbiologists feel that all traditional kingdoms should be
replaced with a system that better reflects the evolutionary history
of life.
1.
Eubacteria – a kingdom or domain consisting of prokaryotic (no
nucleus) microorganisms that possess a peptidoglycan cell wall.
2.
Archaebacteria – a kingdom or domain consisting of prokaryotic
(no nucleus) microorganisms that possess a cell wall not
containing peptidoglycan and that live in harsh environments such
as salt lakes and hot springs.
3.
Eukaryota – all eukaryotes or organisms that contain a nucleus.
**Refer to Handout**
Phylogeny
• Phylogeny is the history or the evolution
of organisms.
• Relationships between organisms are
shown in a phylogenetic tree, where the
tree starts from the most ancestral form
and includes branchings that lead to all of
its descendants.
Phylogenetic Tree
Giant Panda
Dichotomous Key
• Many scientists use a dichotomous key to
classify animals.
• The key is constructed so that a series of
choices can be made, and each choice leads to
a new branch of the key.
• If the choices are made accurately, the end
result is the name of the organisms being
indentified.
Dichotomous Key
Homework
• Read sec 5.1 pg. 134-139
• Questions: Pg. 139 #1-7
• Due Monday & I will review
material with you then
• Email me if you have questions:
stephanieaitken@gpcsd.ca