1. Classification
Chapter 18

2. What’s Wrong Here?

3. Classification
To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner
Taxonomy is the discipline of classifying organisms and assigning each organism a universally accepted name

4. What is the benefit of having a universal classification system?

5. Development of a Classification System
Carolus Linnaeus- developed a two word naming system that is still in use today
In Binomial Nomenclature each species is always assigned a two-part scientific name

6. The first part of the scientific name is the genus
The first part of the scientific name is the genus. The first letter of this name is always capitalized--- Ursus
The second part of the scientific name is the species, which is never capitalized
---- maritimus

7. Now You Try
Examples:
ursus maritimus
homo sapiens
canis familiaris

8. What’s in a Name
When written together, the scientific name includes both the species and genus name of the organism
This should be italicized when typed or underlined when written hand-written

9. Taxonomic Categories
Linnaeus’s system of classification uses 7 taxonomic categories.
Genus is a group of different species that share common characteristics
Kingdom
Phylum
Class
Order
Family
Genus
Species

11. Taxonomic Characteristics
Families are composed of different groups of genera (genus) that share similar characteristics
Families are grouped into orders.
Orders are grouped into classes.
Classes are grouped into phyla (Phylum)
Phyla (phylum) are grouped into a large category called a kingdom

12. Modern Evolutionary Classification
Linnaeus compared structure and anatomy
Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities
Derived Characteristics are those that “show up” in newer parts of a lineage but are not in its older members

13. Modern Evolutionary Classification
Cladograms are diagrams that show evolutionary relationships between groups of organisms

14. Modern Evolutionary Classification
The genes of many organisms show important similarities at the molecular level. These similarities can be used as criteria to help determine classification
All organisms use RNA and DNA to pass on information. All organisms use ATP as an energy-carrying molecule. Similarities in other important chemicals give us another way to compare them

15. Modern Evolutionary Classification
Molecular clocks use DNA comparisons to estimate the length of time that two species have been evolving independently.
This relies on the rate that neutral mutations accumulate in the DNA of different species

17. Kingdoms and Domains
Using new tools available today, scientists have expanded upon Linnaeus’s system of classification.
The 6 kingdom system of classification includes the kingdoms Eubacteria, Archaebacteria, Protista, Fungi, Plantae, and Animalia

19. Kingdoms and Domains
Today, most scientists are now recognizing molecular evidence that requires the addition of a category even larger than kingdom: the domain
Domains:
Archaea
Bacteria
Eukarya