1. Taxonomy and Classification
Biology I

2. Why Classify? 3 - 20 million species on Earth
Less than 2 million have been identified and named
Rainforests and oceans have lots of unidentified species
Need a way to organize to make organisms easier to identify and relationships easier to understand

3. What are Classification and Taxonomy
Classification - Grouping based on similarities
Taxonomy – branch of biology concerned with the grouping and naming of organisms

4. History of Classification
Aristotle
First to Classify living things
Two major groups - Plants and animals
Within these groups, organisms were organized based on where they lived
Doesn’t work
Some live in both land and water
Does NOT show relationships among organisms

5. History of Classification
Carolus Linnaeus
1707 – 1778
Based classification system on physical characteristics
Came up with BINOMIAL NOMENCLATURE
System of naming
2 words – gives species name
Genus
Group of closely related species
Second descriptive word
Example – Homo sapiens; Canis familiaris

6. Why Latin?
Dead language
Never changes
Consistent

7. Characteristics Used by Taxonomists to Classify Organisms
External and internal structures (anatomy)
Chemical make up
DNA
Proteins
Evolutionary relationships

8. How Our Classification System Works
Organisms are grouped into a series of categories – TAXA
The taxa are:
Kingdom – largest, most general group/taxon
Phylum
Class
Order
Family
Genus
Species – smallest, most specific group/taxon

9. Names and Classification show Relationships
Bobcat – Lynx rufus
Lynx – Lynx canadensis
Bobcat and Lynx belong to the same genus
Their classification:
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Carnivora
Family Felidae
Genus Lynx

10. How are relationships determined?
Fossil History and Comparison
Structures of modern organisms are compared with those of fossils

11. How are relationships determined?
Development
Embryonic/larval forms of species can reveal relationships and suggest common origin

12. How are relationships determined?
Biochemistry
The more nucleotide sequences OR amino acid sequences that are shared by two species, the more closely related they are
This is the BEST way to determine relationships
Objective
Quantitative

13. How are relationships determined?
Behaviors
Mating calls and other behaviors lead to reproductive isolation and are used to identify species

14. Goal is creation of an Evolutionary History or Phylogeny
Phylogeny is created
A “family tree”
Shows evolutionary history of a species

16. Our 6 Kingdom System Eubacteria Archaebacteria Protista Fungi Plants
Animals

17. Our 6 Kingdom System 6 kingdoms determined by Characteristics of cells
How they obtain food