1. Organizing Life’s Diversity
Chapter 17

2. EVERYONE classifies… Doesn’t have to be just for living things
In your house, where would I find:
cereal
drinking glasses
socks
blue jeans
bath towels
extra bars of soap

3. Classification
Classify – to group things together based on similarities
Why Classify?
To make organisms/items easier to identify
To make organisms/items easier to compare
How do we classify?
Compare Traits – features or characteristics of an organism/item
When dealing with living things, the science of Classification is called Taxonomy

4. 2 Big Challenges of Classification
1. Many different kinds of living things -- diversity
Today we have identified and named 1.5 million species
Millions more are believed to be unclassified
Organisms scattered all over the world, some in harsh, difficult to reach environments
2. Classifications are made by people
Opinions may differ from scientist to scientist

5. Timeline of Classification
– 322 B.C. Aristotle
2 Kingdom Broad Classification
Carl Linnaeus
2 Kingdom Multi-divisional Classification
(Kingdom, Phylum, Class, Order, Family Genus, Species)
3. Evolutionary Classification – (After Darwin)
Group By lines of Evolutionary Descent
4. 5 Kingdom System – 1950s
5. 6 Kingdom System – early 1990s
6. 3 Domain System – late 1990s

6. Early Classification – Aristotle 384-322 B.C.
Plant Animal
Green Not green
Does not move Does move
Shrub
Air
Land
Water
Tree
Herb
Size
Pattern of growth
Where live

7. How would you classify these using the Plant/Animal system?
Aristotle’s Grouping of life not specific enough

8. Carl Linnaeus Linnaeus (1735) Swedish Botanist
Reworked Classification system
*Based on Body structure -- morphology
Called his classification Systema Naturae
Used a hierarchy of categories to classify
*Compared physical traits of Organisms
*Used Comparative Morphology

9. Linnaeus Divisions Still Used in Modern Classification
1. Kingdom – largest group
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
(Most Closely Related)

10. Mnemonic Device – To help remember categories and order
Kingdom - King
Phylum - Phillip
Class – Came
Order – Over
Family For
Genus Ginger
Species - Snaps

12. Taxons Within each category, a particular group is called a Taxon
Many Taxons for each category
Ex:
Mammalia is the Taxon for the Class category in Humans
Carnivora is the Taxon for the Order category in Lions

13. Similarities/Changes Linnaeus Made to Aristotle’s System
*Both had 2 “Kingdom” Systems
Plantae and Animalia
Differences:
1. Plants and Animals were classified using more divisions - to account for diversity
2. Each division from Kingdom to species is based on specific traits
Ex: Vertebrae, Mammary Glands, Diet
3. Taxons of each group are descriptive of trait being used in forming that group
Ex: Class Mammalia – mammary glands are used to nurse young

14. Linnaeus Introduced Scientific Naming
Binomial Nomenclature is the 2 word scientific name of an organism
Uses Genus and Species
Genus is capitalized, not species, all italicized
In writing the name, can’t italicize, so underline
Used Latin – Universal unifying, “dead” language
*Latin can be understood by all scientists, regardless of native language
*Uniform, unlike common name usage
Ex: Cougar, Puma, Panther- all same organism
name depends upon where you live, but Scientific name is the same WORLDWIDE
Felis concolor

15. Example Classification
Lion
1. Kingdom – Animalia (all Animals)
2. Phylum – Chordata (All vertebrate animals)
3. Class – Mammalia (All Mammals – mammary glands)
4. Order – Carnivora (Meat eaters)
5. Family – Felidae (includes all Cats)
6. Genus – Panthera (Includes all roaring Cats)
7. Species – leo (Lions)

16. From Kingdom to Species

18. Classification Key Also Known as: Dichotomous Key, Biological Key
Useful in Identifying Organisms
Based on Comparison of Morphological Traits
Use physical features to compare, contrast
Determine if Organism is in group or not, based on Key criteria
At each level you only have a few contrasting characteristics to choose from (if have, if not have)
Ex: Tennis shoe, non Tennis shoe
Body shape plans, Characteristics such as fur
Refer to your Shark lab handout

19. Tools Used to Classify Organisms
Comparative Morphology (structural similarities)
Breeding behavior (behavioral similarities)
Geographical distribution (biogeography)
Chromosome comparisons
Biochemistry
Evolutionary Relationships

20. Comparative Morphology
Body structure
Presence/absence of body parts
Ex. Number of limbs
Ex. Presence of feathers
Ex. Presence of flowers
*REMEMBER THOUGH--
This can be misleading – divergent and convergent evolution could play a part and appearance is NOT indictitive of true taxonomic relationships…..

21. Breeding Behavior Differs between species Ex. Mating calls of frogs
Differences in breeding behavior allows for SPECIATION to occur, and can result in isolation

22. Biogeography Finches, tortoises in Galapagos
Bears on different continents
Sugar glider and flying squirrel

23. Chromosome comparisons and Biochemistry
Number and structure of chromosomes are set from species to species!!!
Similarities in chromosomes and the proteins that are made leads to idea that orgs are related.
Ex. Cauliflower, cabbage, kale, broccoli

24. Molecular clocks
Page 530

25. Two types of data for molecular clocks…
Mitochondrial DNA –

26. Ribosomal RNA –

27. Evolutionary Relationships – Cladistics vs. Systematics
Both are Phylogenetic Classification models – deal with evolutionary history
Difference
*Cladistics uses a “order of appearance” approach – cladogram
this shows groups of organisms evolving from a common ancestor and utilizes “derived characters”, but not specific times

29. In cladistics, similar characteristics that come from a common ancestor are used to divide organisms into groups.
A cladogram will begin by grouping organisms based on a characteristic displayed by all the members of the group.
Subsequently, the larger group, or clade, will contain increasingly smaller groups (clades) that share the traits of the clades before them, but also exhibit distinct changes as the organism evolves.
To make a cladogram, scientists first collect data on the features of all the organisms they hope to classify.
This data is then analyzed to determine which characteristics were present in what could have been a common ancestor and which might have been developed in
later times.

30. Page 525

31. Cladogram vs. Comparative (Traditional) Morphology p.452
Derived Characters
Common Ancestor 
<-- Common Ancestor 
Common Ancestor 
Common Ancestor 

32. Systematics uses a fan-like approach that communicates a timeline
Instead of a few derived characters, systematics uses as many characteristics of orgs as possible and makes groupings based on overall degree of similarity

34. Timeline of Classification
– 322 B.C. Aristotle
2 Kingdom Broad Classification
Carl Linnaeus
2 Kingdom Multi-divisional Classification
(Kingdom, Phylum, Class, Order, Family Genus, Species)
3. Evolutionary Classification – (After Darwin)
Group By lines of Evolutionary Descent
4. 5 Kingdom System – 1950s
5. 6 Kingdom System – early 1990s
6. 3 Domain System – late 1990s

35. From 2 Kingdoms to 6 p. 458

36. 6 Kingdom System moves to 3 Domains
Animalia
Plantae
Fungi
Protista
Eubacteria
Archaeabacteria

37. 4. Three Domain System 1. Domain Bacteria
Corresponds to Eubacteria Kingdom
Unicellular Prokaryotic Organisms
No Nucleus
Ecologically Diverse – live everywhere!
Metabolically Diverse
Cell Walls contain substance called Peptidoglycan – special protein and sugar
Trait used to distinguish between Bacteria
and Archaea
Target of many antibiotics

38. Three Domain System 2. Domain Archaea – “Ancient Bacteria”
Corresponds to Kingdom Archaebacteria
Unicellular, Prokaryotes
Metabolically Diverse
No nucleus
Live in Extreme environments like those of early Earth
Cell walls without Peptidoglycan
a trait used to distinguish between Archaea and Bacteria domains

39. Three Domain System 3. Eukarya Contains Kingdoms:
Protista, Fungi, Plantae, Animalia
Eukaryotic, single or multi-cellular Organisms
Nucleus
Most visible life
Humans are in Domain Eukarya