1. Chapter 18 Classification
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2. 18-1 Finding Order in Diversity
Why Classify Organisms??
Biologists use classification systems to name organisms and group them in a logical order
Taxonomy: Scientists classify organisms and assign each organism a universally accepted name

3. The History of Organization
Aristotle BC
Interested in biological classification.
Patterns in nature.
Carl Linnaeus
ACE
Father of Biological
Classification!

4. Aristotle Developed the first system of classification.
He classified all living things into plants and animals.
Animals were grouped depending on where they lived. (On land, in air or in water)
Later scientist became convinced that his system did not work because of organisms living in multiple habitats.

5. Carolus Linnaeus
Developed the system of classification that is still used today.
He selected physical characteristics that led to classification based on close relationships of organisms.
He used characteristics such as bats having hair and feeding their young milk to classify the organisms.
The system devised by Linnaeus gives each organism two names called Binomial Nomenclature.

6. 18-1 Assigning Scientific Names
For many species, there are often regional differences in their common names
EX: Buzzard in the UK refers to a hawk, Buzzard in the US refers to a vulture
To eliminate such confusion, scientists agreed to use a single name for each species

7. 18-1 Assigning Scientific Names
Binomial Nomenclature: Scientists assign each kind of organism a universally accepted name in the system
Two word system using the Genus and Species
Words are always written in italics
First word (Genus) is capitalized and second word (Species) is lowercase
Second word is a Latinized description of a particular trait
Developed by an 18th C. Swedish botanist named Carolus Linnaeus
EX: Grizzly Bear = Ursus arctos

8. 18-1 Assigning Scientific Names
Differences in Binomial Nomenclature:
1st part of scientific name is genus to which the organism belongs
A genus is composed of a number of closely related species
2nd part of scientific name is unique to the species within the genus
EX: Ursus arctos= Grizzly Bear, Ursus maritimus= Polar Bear
EX: Papio annubis and Papio cynocephalus do NOT belong to the same species since the species part of the name is different. However, they do belong to the same genus

9. Common name: Robin
Erithacus rubicula
Turdus migratorus

10. Common name: Black and Polar Bear
Ursus americanus
Ursus maritimus

11. 18-1 Assigning Scientific Names
Linnaeus’s System of Classification:
Based on Taxonomy naming system
Taxonomy: a group at any level of an organization is referred to as a taxon
Is hierarchical and consists of 7 taxonomic categories
From largest to smallest:
Kingdom (King)= Made up of phylums
Phylum (Phillip) = Made up of several different classes
Class (Came) = Made up of several different orders
Order (Over) = Made up of several different families
Family (For) = Made up of several different genuses
Genus (Grape) = Made up of several different species
Species (Soup)

13. 18-1 Assigning Scientific Names
Examples of Taxonomic Levels:
The most general and largest of Linnaeus’s system is the Kingdom
Linnaeus recognized the kingdoms of plants (Plantae) and animals (Animalia)
The class of Mammalia includes mammals which are organisms that have:
Are warm-blooded
Have body hair
Produce milk for their young

14. 18-2 Modern Evolutionary Classification
Traditional classifications like Linnaeus’s tended to take into account primarily general similarities in appearance
However, some organisms that ARE NOT closely related look alike because of convergent evolution!
Evolutionary Classification: The procedure of grouping organisms based on their evolutionary history
Species within one genus should be more closely related to each other than a species in another genus
All genera within a family share a common ancestor. Similar genes

15. 18-2 Modern Evolutionary Classification
Derived Characters: An evolutionary innovation
EX: Free swimming larva, segmented body
Cladistic Analysis: Analysis that focuses on the order in which derived characters appear in an organism
Looks only at derived characters, or those characteristics that are evolutionary innovations (EX: body structures, adaptations)
New characteristics emerge as lineages evolve over time
Cladogram: a table analyzing derived characters that shows the evolutionary relationship between organisms
Helps scientists understand how lineages branched from one another in the course of evolution
Shows the order in which derived characters evolved

16. 18-2 Modern Evolutionary Classification
Similarities in RNA and DNA:
Similar genes are evidence of common ancestry
Similarities in DNA can help determine classification and evolutionary relationships
EX: A cow and a yeast’s degree of relationship can be determined from their genes
EX: Scientists have found that humans and yeast have similar genes for the assembly of certain proteins (Myosin)
All organisms use DNA and RNA to pass on information

17. 18-2 Modern Evolutionary Classification
Similarities in RNA and DNA Cont…:
DNA evidence can help show the evolutionary relationship between organisms and how species have changed
EX: Presence of similar genes in very dissimilar organisms implies that the organisms share a common ancestor like vultures and storks!

18. 18-3 Kingdoms and Domains
In the 1800’s scientists used a 3 kingdom classification system:
Animals, Plants, Protista
Scientists grouped organisms according to how long they have been evolving independently
Biologists knowledge of diversity of life continued to grow
We now know there are 6 Kingdoms:
Protista (used to be grouped with Plants)
Fungi
Plantae
Animalia
Eubcteria (used to be grouped as the Monera category)
Archaebacteria (used to be grouped as the Monera category)

19. 18-3 Kingdoms and Domains The Three Domain System:
Modern analysis of evolutionary trees have given rise to a new taxonomic category– Domain
A domain is more inclusive and larger than a kingdom
There are 3 Domains:
Eukarya: includes kingdoms protist, fungi, plants, & animals
Archaea: includes kingdom Archaebacteria
Bacteria: Includes kingdom Eubacteria
The 3 domains are thought to have diverged from a common ancestor before the evolution of the main groups of eukaryotes
Recognizes fundamental differences between 2 groups of prokaryotes- Bacteria & Archaea

20. 18-3 Kingdoms and Domains Domain Archaea: Unicellular
Found in extreme environments– deep sea bacteria, make their own food (autotroph) using energy derived from minerals coming form; without oxygen
Cell membranes contain unusual lipids
Corresponds to the kingdom Archaebacteria

21. Halophiles (like salt)
Thermophiles (like heat)

22. 18-3 Kingdoms and Domains Domain Bacteria: Unicellular Heterotroph
Cell walls are thick & rigid & contain peptidoglycan
Corresponds to the kingdom Eubacteria
Come in 3 basic shapes --- cocci (spheres), bacilli (rod shaped), spirilla (corkscrew shape)
Some need oxygen to survive & others do not

23. Eubacteria
Staphylococcus aureus 
Bacillus anthracis
E. coli

24. 18-3 Kingdoms and Domains Domain Eukarya: Protista:
Consists of all eukaryotes (cells with a nucleus)
Consists of the 4 kingdoms:
Protista:
organisms that cannot be classified as plants, animals, or fungi
Usually unicellular
Have chloroplasts
Membrane-bound organelles
Move by flagellum, cillia, or pseudopods
EX: Algae

25. Amoeba
Rotifer
Euglena
Algae

26. 18-3 Kingdoms and Domains Kingdom Fungi:
Heterotrophs that feed on dead or decaying matter. Do not contain chlorophyll
decomposers & recyclers
Can be single or multicelled
Cell walls contain chitin
Non-motile
Lack true roots, stems, & leaves
EX: Mushrooms & yeast

27. Mold
Mushrooms
Ringworm
Yeast

28. 18-3 Kingdoms and Domains Kingdom Plantae: Photosynthetic autotrophs
Multicellular
Contain chlorophyll inside of chloroplasts
Undergo photosynthesis
Cell walls contain cellulose
All plants that reproduce sexually
EX: mosses, ferns, flowering plants, cone-bearing plants, etc…

30. 18-3 Kingdoms and Domains Animalia: Multicellular & heterotrophic
Cells contain a nucleus and membrane bound organelles
Show levels of organization including cell, tissue, organ, & system
Cells are specialized for particular functions
No cell walls
Can move about
EX: animals

32. What are Dichotomous Keys?
a method for determining the identity of something (like the name of a butterfly, a plant, a lichen, or a rock) by going through a series of choices that leads the user to the correct name of the item.
Dichotomous means "divided in two parts".

33. Using a dichotomous key
At each step of the process of using the key, the user is given two choices; each alternative leads to another question until the item is identified.
1a. If the leaves are flat….go to question 4.
1b. If the leaves are needle-like….go to question 2.
2a. Are the needles in a bunch? Go to question 5
2b. Are they spread along the branch?“…pine tree
Eventually, when enough questions have been answered, the identity of the tree is revealed.

34. Why is Taxonomy Important?
New Discoveries
Unknown species discovered.
Questions
Two new discovers have been made. Living animal and fossil. Questions: What is this animal and how does it behave. Where does it fit into the big picture. How can we answer these question. Gather suggestions.
New fossil Uncovered.
How can you answer these questions?