1. Taxonomic Systems
Section 9.1

2. The More Specific The Better
READ ONLY
The More Specific The Better
An eyewitness describing a getaway vehicle could say the following:
The colour
The model
The year
The license plate number
The best evidence of all!!

3. Classifying Organisms
One purpose of a classification system is to allow the accurate identification of a particular organism.
The second purpose is to recognize natural groupings of living things.

4. Taxonomy The practice of classifying organisms is known as taxonomy.
Founded nearly 300 years ago by a Swedish botanist named Carolus Linnaeus.
He used simple physical characteristics to identify different species and organize them into groups.

5. Hierarchy of Groups READ ONLY
As members of the animal kingdom, the bee, shark, horse, dog and oyster have certain things in common.
On the other hand, these animals are obviously not very much alike.
There are different degrees of similarity among animals.
A horse is more like a dog than like a shark.

6. Taxa
To distinguish such different degrees of similarity between organisms, each kingdom is subdivided several times into a series of progressively smaller groups.
Each group is called a taxon (plural taxa).
Kingdoms are the largest and most general taxa.
Species are the smallest and most specific taxa.

7. Organisms in this taxon
Example
Organisms in this taxon
(READ ONLY)
Kingdom
Animalia
Bee, frog, shark, horse, oyster, dog, cougar, lynx, bobcat
Phylum
Chordata
Shark, horse, frog, dog, cougar, lynx, bobcat
Class
Mammalia
Horse, dog, cougar, lynx, bobcat
Order
Carnivora
Dog, cougar, lynx, bobcat
Family
Felidae
Cougar, lynx, bobcat
Genus
Lynx
Lynx, bobcat
Species
Lynx canadensis
Lynx rufus
Bobcat

8. Naming a Species Linnaeus’s two word method:
Felis domesticus (the house cat).
Many of these names are based on Latin or Greek words.
These names often reflect characteristics of the organisms, or in other cases, the names are given to honour a fellow scientist or historical figure or a location where the animal lives.

9. Binomial Nomenclature
The system of using a two-word name for each species is called binomial nomenclature.
The first word: name of organism’s genus
The second word: identifies the particular species.
The first letter of the first word is capitalized.
The entire name is in italics.
There may be several species with the same genus name.

10. Genus: Canis Canis lupus: wolf Canis latrans: coyote
Canis familiaris: domestic dog
The fact that the above animals have the same first name tells you that they are all in the same genus of dog-like animals and are very similar to one another.

11. Common Names Why not just use common names like cat?
Common names are not precise.
There are many different species of cats: wild cats and domestic cats.
In addition, people in different regions may use different common names to refer to the same species. For example: puma, cougar and mountain lion are three different names for the same animal.

12. Misleading Information
Common names can give you misleading ideas about the basic characteristics of an organism and the group in which it should be classified.
Should shellfish, starfish, jellyfish, crayfish and catfish all be in the single group, fish?
Biologists place each of these members of the animal kingdom in a separate phylum.

13. Where do we fit in? Taxon Humans Kingdom Animalia Phylum Chordata
Class
Mammalia
Order
Primata
Family
Hominidae
Genus
Homo
Species
Homo sapiens
Chimpanzee
Animalia
Chordata
Mammalia
Primata
Hominidae
Pan
Pan troglodytes
Pan paniscus

14. Dichotomous Key
Goal of a taxonomist: identify an organism at the species level.
Dichotomous key: an identification tool consisting of a series of two-part choices that lead the user to a correct identification.

15. Example
1. a. Organism is microscopic PARAMECIUM.
1. b. Organism is macroscopic go to 2
2. a. Organism is a plant go to 3
2. b. Organism is an animal go to 5
3. a. Plant has a woody stem go to 4
3. b. Plant has a herbaceous stem DANDELION.
4. a. Tree has needle like leaves PINE TREE.
4. b. Tree has broad leaves OAK TREE.
5. a. Organism lives on land go to 6
5. b. Organism lives in water CLAM.
6. a. Organism has 4 legs or fewer go to 7
6. b. Organism has more than 4 legs ANT.
7. a. Organism has fur go to 8
7. b. Organism has feathers ROBIN.
8. a. Organism has hooves DEER.
8. b. Organism has no hooves MOUSE.

16. Homework
Dichotomous key handout
p. 331 #1-5