1. Classification: Using Dichotomous Keys

2. Have you ever wondered what some plant or some animal was called?
There have been over 1 million species identified and named (classified) on earth. (Though scientists estimate that there are somewhere between million species on earth.)
We can’t possibly memorize all of them so we rely on keys made by specific experts to identify them.

3. For ex: What if we have little knowledge of these organisms?
The Genus name of typical bird/reptile specimens… ?
Anas ?
Anolis ?
Malaclemys
Gallas
Elaphe ? ?

4. Dichotomous Key
A dichotomous key uses a series of paired questions to identify previously classified/named organisms

5. Dichotomous Key The Genus name of typical specimens…
1. a) It has feathers …………… Go to 2
b) No feathers …………… Go to 3
2. a) It has webbed feet………… Anas
b) No webbed feet…….… Gallas
3. a) It has legs……………………Go to 4
b) No legs…………………….. Elaphe
4. a) It has a “shell” …………….. Malaclemys
b)No shell………………………. Anolis

6. Your turn!
Use a typical dichotomous key to identify the common name of the Arizona fish species pictured.
Become an expert and make your own dichotomous key for the given “organisms”.

7. Classification of Life
Journal Notes

8. Classification
grouping organisms in a logical manner.

9. Taxonomy Grouping method based on: Anatomy DNA and proteins
Evolutionary relationship
Developmental similarities

10. Important People life: “Plant” or “Animal”.
Aristotle (300 B.C.)
life: “Plant” or “Animal”.
Carl Linnaeus (1750s)
Grouped based on morphology
Came up with 7 levels of Taxonomy
We now use 8 levels

11. How to Classify an Organism
Eight Major “taxa” or groups.
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

12. Scientific Names 2 word scientific name.
Uses Latin
Binomial Nomenclature – “two name naming list”.
Genus species
How is it written?
Homo sapiens

13. Examples Scientific Name Felis domesticus Panthera leo Canis lupus
Canis lupus familiaris
Common Name
House cat
Lion
Wolf
Domestic dog

14. Example: Humans Domain = Kingdom = Phylum = Class = Order = Family =
Genus =
Species =
Eukarya
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens

15. Assignment:
Arizona Animal classification assignment. Due Monday. You will present your animal to the class. Please be prepared.

16. Classification of Life
Journal Notes Continued

17. Classification Today
Organisms are grouped based on evolutionary relationships
Cladogram: Diagram that shows the evolutionary relationships among organisms

18. Taxonomy Today Based on:
Homology – Organisms with similarly evolved structures are grouped together.
Molecular Biology – Organisms with similar DNA are grouped together.

19. Valid Cladograms: Show evolutionary relationships
Conical Shells
Appendages
Crustaceans
Gastropod
Crab
Limpet
Crab
Barnacle
Barnacle
Limpet
Molted exoskeleton
Segmentation
Tiny free-swimming larva
CLASSIFICATION BASED ON ANALOGOUS STRUCTURES
Cladogram – Based on Homology

20. Cladogram of Modern Vertebrates

21. Nodes are common ancestors
Who is D’s closest relative?
What do the blue lines represent?
What do the green dots represent? C
Inherited characters
Nodes are common ancestors

22. Homework Assignment AZ Plant Mini-Poster due Thursday
17.2 Main Ideas and Figures worksheet due tomorrow.