1. Section 5.1 Classification of Species
Chapter 5
Section 5.1
Classification of Species

2. 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.

3. 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.

4. 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.

5. 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.

6. 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

7. Levels of classification
Dandelion
Housefly
Human
Kingdom
Plantae
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

8. 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

9. 6 Kingdom Classification System
Eubacteria
Archaebacteria
Protista
Fungi
Plantae
Animalia
**Refer to Handout**

10. 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.
Eubacteria – a kingdom or domain consisting of prokaryotic (no nucleus) microorganisms that possess a peptidoglycan cell wall.
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**

11. 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.

12. Phylogenetic Tree

13. Giant Panda

14. 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.

15. Dichotomous Key

16. Homework Read sec 5.1 pg. 134-139 Questions: Pg. 139 #1-7
Due Monday & I will review material with you then
me if you have questions: