1. Finding Order in Diversity
CLASSIFICATION
Finding Order
in Diversity
There is a student study guide sheet that goes with this Powerpoint lesson for TEKS Biology.

2. DEFINE TAXONOMY
Discipline of classifying organisms and assigning each organism a universally accepted name.
In the United Kingdom, the word buzzard refers to a hawk, whereas in many parts of the United States, buzzard refers to a vulture.

3. WHY CLASSIFY?
1. To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner.
Ask students: What characteristics do these organisms have that might lead scientists to group them together?
What differences do they have that distinguish one from the other?

4. WHY CLASSIFY?
When taxonomists classify organisms, they organize them into groups that have biological significance.
What is this first organism?
How does this second organism relate to the first?
And the third?
And the fourth?
All of these organisms are known as birds. When we hear the word bird, we immediately form a mental picture in our minds of what birds look like.

5. WHY CLASSIFY?
Classification makes life easier. What are some ways we classify?
Think of all the different types of music there is. What if you wanted to buy a new CD at the store? How do you go about finding the CD?
When you grocery shop? How do you know where to look for Lucky Charms cereal?
At school, what are some ways that we classify students?
Think of how much more difficult our lives would be without the alphabet, without numbers, without the Dewey decimal system, without a phonebook.

6. LINNAEUS’S SYSTEM OF CLASSIFICATION
Linnaeus’s hierarchical system of classification includes seven levels. They are, from largest to smallest, Kingdom, Phylum, Class, Order, Family, Genus, Species.
You may want to have students draw a pyramid and draw 6 horizontal lines across to divide the pyramid up into 7 sections. Then have the students list the 7 taxonomic categories from bottom to top, starting with Kingdom at the bottom in the widest section and ending with species at the top in the smallest section.

7. LINNAEUS’S SYSTEM OF CLASSIFICATION
The Kingdom is the largest and most inclusive (includes) of the taxonomic categories.
Species is the smallest and least inclusive of the taxonomic categories.

8. LINNAEUS’S SYSTEM OF CLASSIFICATION
4. The more taxonomic levels that two organisms share, the more closely related they are considered to be.

9. EVOLUTIONARY CLASSIFICATION
Biologists group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.
Define Phylogeny: The study of evolutionary relationships among organisms.

10. EVOLUTIONARY CLASSIFICATIONB C D E F
Clade or
lineage
TIME
Definition of Clade: A group of organisms, such as a species, whose members share homologous features derived from a common ancestor.
The American Heritage® Dictionary of the English Language, Third Edition copyright © 1992 by Houghton Mifflin Company. Electronic version licensed from INSO Corporation; further reproduction and distribution restricted in accordance with the Copyright Law of the United States. All rights reserved.
Speciation: formation of two
new species from one

11. EVOLUTIONARY CLASSIFICATION
Classification using Cladograms
a. Cladograms are diagrams that show the evolutionary relationships among a group of organisms.
b. The cladogram on the next slide shows the evolutionary relationship among several vertebrates.

12. CLADOGRAM Jaws Lungs Claws or Nails Feathers Hagfish Fish Frog Lizard
Pigeon
Mouse
Chimp
Fur &
Mammary
Glands

13. CLADOGRAM
c. The characteristics listed below the line are called derived characters (traits).
d. When the derived character appears above an organism, the organism lacks that derived character. When the derived character appears below the organism, the organism possesses that derived character.

14. VENN DIAGRAMS
1. Venn Diagrams can be used to make models of hierarchical classification schemes. A Venn diagram is shown below: A. B. D. C.

15. Four groups are represented by circular regions
Each region represents different taxonomic levels.
Regions that overlap, share common members.
Regions that do not overlap do not have common members.

16. Animals with backbones Insects All animalsD.
Matching:
Mammals
Animals with backbones
Insects
All animals C B D A

17. ASSIGNING SCIENTIFIC NAMES
Using common names is confusing because many organisms may have several different common names.
The cougar is also known as the mountain lion, puma or catamount…thus the need for a scientific name.
Photo courtesy Texas Parks and Wildlife Department © 2004
Felis concolor

18. A Swedish botanist named Carolus Linnaeus developed Binomial Nomenclature, a two-word naming
system for naming
all species on earth.
What do botanists
study?
Botanists study plants.

19. ASSIGNING SCIENTIFIC NAMES
2a. The first part of the scientific name is the genus. This word is always written first and the first letter is capitalized. It appears in italics or is underlined.
Homo sapien
Grizzly bear picture is reproduced with permission from WWF. © 2004 WWF- World Wide Fund For Nature (Formerly World Wildlife Fund). All Rights Reserved
Ursus arctos

20. ASSIGNING SCIENTIFIC NAMES
2b.
The second part of the scientific name is the species name. This word is always written second and the first letter is lower-case.
It appears in italics or is underlined.
Homo sapien
Ask students to notice how both words appear: in italics or they may both be underlined.
Ursus arctos

21. LINNAEUS’S SYSTEM OF CLASSIFICATION
What do the scientific names of the polar, grizzly and panda bears tell you about their similarity to each other?
The shared genus name Ursus indicates that the grizzly bear and polar bear are more closely related. The panda bear is more distantly related because it does not belong to the same genus as the other two.
Ursus maritimus
Ursus arctos
Ailuropoda melanoleuca
Pictures reproduced with permission from WWF. © 2004 WWF- World Wide Fund For Nature (Formerly World Wildlife Fund). All Rights Reserved

22. THINKING CRITICALLY Kingdom Phylum Class Order Family Genus Species
Organism
Cat
Wolf
Fly
Kingdom
Animalia
Phylum
Chordata
Arthropoda
Class
Mammalia
Insecta
Order
Carnivora
Diptera
Family
Felidae
Canidae
Muscidae
Genus
Felis
Canis
Musca
Species
F. domesticus
C. lupus
M. domestica
Have students study this chart. The next slide lists three questions to answer using this chart. You may have to advance to the next slide, let students read the question and then come back to the chart so they can find the answer.

23. THINKING CRITICALLY What type of animal is Musca domestica?
From the table, which 2 animals are most closely related?
3. At what classification level does the evolutionary relationship between cats and wolves diverge (become different)?
Animal; insect
Cat and Wolf
Family Level