1. Chapter 17: The History and Diversity of Life
Section 17-2: Finding Order
in Diversity

2. Why do we classify?
A classification system identifies objects and gathers them into groups whose members are similar to each other
Biological classification systems based on a logical method of naming things; group organisms based on common features

3. Biological Classification
Biologists had to create a universal set of rules for naming organisms, allowing each species to have a universally accepted name
The science of naming organisms and assigning them to groups is called taxonomy. (taxon = name group)

4. Biological Classification
Carolus Linnaeus (Swedish botanist) developed the system of binomial nomenclature with which we identify species
Binomial = two word
Nomenclature = naming system

5. Biological Classification
Each species is named used two Latin words called the GENUS and SPECIES to identify it
A genus is defined as a group of related species (plural is genera)
Hopefully you all remember the definition of species!

6. Biological Classification: Example
Common house cat scientifically named Felis domesticus
Felis = genus and domesticus = species
Always in italics, genus capitalized
When written, should be underlined

7. Further Classification
A family = group of related genera.
An order = group of related families.
A class = group of related orders.
A phylum = group of related classes. (In plants, division is used instead of phylum.)
A kingdom is a group of related phyla.

8. Further Classification
Looking at the house cat again:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: Felis
Species: domesticus

9. Classification
How can you remember the seven taxa?
Use a pneumonic!

10. The Kingdoms of Life
Modern classification shows common descent and evolutionary relationship
By analyzing genetic, biochemical, and physical similarities, scientists have agreed on six kingdoms

11. The Kingdoms of Life Eubacteria Archaebacteria Protista Fungi Plantae
Animalia