1. Taxonomy Notes Nowicki Biology, Chapter 17

2. 17.1: The Linnaean System of Classification
Linnaeus developed the scientific naming system still used today
taxonomy – science of naming and classifying organisms
hierarchical – multilevel scale in which each level is contained or included in every level above it
based on the system developed by Carolus Linneaus

3. 17.1: The Linnaean System of Classification
Taxonomy- Discipline of classifying organisms and assigning each organism a universally accepted name.
Why classify?
Classification makes life easier.
What are some ways we classify?

4. 17.1: The Linnaean System of Classification
Looking at the Figure 1: Animal Hierarchy:
Dogs are _____________ and _________________
Are birds animals? ______
Are fish mammals? _____
Mammals
Animals
yes no

5. taxon – a level of classification; the basic level is species; taxa is the plural
the diagram below shows 8 taxa in the hierarchical system of classification we use
most general/least specific (includes the greatest number of organisms
most specific - contains only one single kind of organism

7. Mnemonic (Dear King Phillip Came Over For Grape Soda)
=Domain
=Kingdom
=Phylum
=Class
=Order
=Family
=Genus
=Species
Did
King
Philip
Come
Over
For
Great
Spaghetti?
Make your own mnemonic
& share with the class!
Retrieved November 7, 2012 from:
Retrieved November 7, 2012 from:

8. 17.1: The Linnaean System of Classification
(Domain is not shown in the diagram to the left)
When looking at the taxonomic hierarchy (Domain, Kingdom, etc), Which taxon has the most diverse group of organisms?
Kingdom Animalia
Which taxon is the least diverse?
Species (Dendroica fusca)

9. 17.1: The Linnaean System of Classification
Scientific Naming
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.
We use binomial nomenclature to assign scientific names.
The scientific name for a cougar is Felis concolor

10. 17.1: The Linnaean System of Classification
binomial nomenclature – a system of naming in which each species has a two-part scientific name
Two different species cannot have the same scientific name
Importance? Binomial nomenclature provides a standard of communication among biologists, regardless of their native language

11. 17.1: The Linnaean System of Classification
scientific name – genus and species names of an organism
- basis for our system of naming organisms.
two parts:
o genus – first part/word of the scientific name
always capitalized and italicized (typing) or underlined (handwriting)
can be used alone
Homo sapiens
Ursus arctos

12. 17.1: The Linnaean System of Classification
o species – second part/word of the scientific name
never capitalized
always italicized (typing) or underlined (handwriting)
can never be used alone
Homo sapiens
Ursus arctos

13. Scientific Names

14. Helix pomatia Vespula germanica
What do these names all have in common?
Helix pomatia Vespula germanica
Carcharodon carcharias Crocodylus acutus
Capitalized
&
Italicized

15. What do these all have in common?
When Written:
What do these all have in common?
Capitalized →
←underlined

16. Scientific Names
EXAMPLE: One of the most commonly used scientific names is Escherichia coli. This is the scientific name of a rod-shaped bacteria that lives in your intestines, helping you digest your food and produce vitamin K (necessary for blood clotting). It is also used in research involving bacteria and is sometimes linked to outbreaks of food-poisoning.
When the name has been typed, it should look like this:
Escherichia coli
When the name has been handwritten, it should look like this:
It is okay to abbreviate the full name like this: E. coli or Escherichia, but never like this: coli
Why are all scientific names so weird? Why can’t they just be “in English”?
Scientific names are written in Latin because it is not a language spoken in any country today; therefore, it is a nonpolitical choice.
There are several divisions of the International Code of Nomenlature that govern the naming of all organisms.

17. examples of scientific names - named after people (ashei named after botanist Ashe), named after location (Lupinus texensis), and characteristics (Mimus polyglottos - mimics many voices), cornutum - crown, novemcinctus - 9 belts,

18. The Linnaean classification system has limitations
Linnaeus based his classification on physical similarities
today we have technology that allows us to look at molecular similarities (amino acid sequences in proteins that are based on nucleotide sequences in the genes of the DNA)
remember that organisms can look similar due to analogous characteristics resulting from convergent evolution (think back to evolution: bird wings and butterfly wings have the same function, different structure)
classification should be based on homologous characteristics resulting from divergent evolution (think back to evolution: homologous characteristics share the same structure, have a common ancestor but have a different function)
molecular homology is much more definitive in determining species relationships than physical analogy

19. 17.1: The Linnaean System of Classification
The more taxonomic levels that two organisms share, the more closely related they are.
Which bears are most closely related?
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

20. 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.

21. Use the chart Using the chart on the previous slide and your notes
1. What type of animal is Musca domestica?
Animal; insect
2. From the table, which 2 animals are most closely related?
Cat and Wolf
3. At what classification level does the evolutionary relationship between cats and wolves diverge (become different)?
Family Level

22. dichotomous key – tool used by scientists to identify organisms in the field based on defining characteristics
arranged in pairs of questions to which the answer is generally yes or no, followed by a direction of what pair of questions to go to next until the organism has been identified
key to using this tool is always starting with the first pair of questions!

23. Dichotomous Key
Norns are a very rare and actually imaginary animals that belong to the genus Norno. There are 8 different species of Norno, generally located in specific regions of the world. Use the key to identify the Norns shown.
A = kentuckyus
B = californius
C = walawala

24. 17.2: Classification Based on Evolutionary Relationships
phylogeny – evolutionary history for a group of species
can be shown as branching “family trees”
think back to evolution and phylogenetic trees: does this reflect convergent or divergent evolution?
Divergent

25. 17.2: Classification Based on Evolutionary Relationships
Cladistics is classification based on common ancestry.
cladistics – classification based on common ancestry
goal is to place species in the order in which they descended from a common ancestor
cladogram – diagram based on patterns of shared, derived traits that shows the evolutionary relationships between groups of organisms
clade – group of species that share a common ancestor

26. 17.2: Classification Based on Evolutionary Relationships
derived characters – traits that can be used to figure out evolutionary relationships among a group of species; traits are shared by some species but are not present in others
the more closely related species are, the more derived characters they will share
outgroup – group of species that shares no derived characters with the other groups being studied

27. Cladogram 1. Which are the derived characters in the cladogram below?
2. Circle the Hagfish and label it, “outgroup.” Explain why it’s the outgroup.

28. 17.2: Classification Based on Evolutionary Relationships
Complete Quicklab: Classifying – Construct a Cladogram, p. 511

29. 17.2: Classification Based on Evolutionary Relationships
Cladograms are important tools in classification because they represent true evolutionary relationships based on all available data, especially molecular homology--DNA &/or amino acids.

30. What derived traits do groupers have?
jaw bones, vertebral column
Do Lancelets contain a vertebral column? no
What organism is closely related to the wolf?
turtle

31. 17.3: Molecular Clocks
Molecular clocks use mutations to estimate evolutionary time
molecular clocks – models that use mutation rates to measure evolutionary time
basis for using molecular data to determine relatedness of 2 organisms
o more differences between the genes or proteins of organisms means they are more distantly related they are (they shared a common ancestor a long, long time ago)
o fewer differences between the genes or proteins of organisms means they are more closely related (they shared a common ancestor more recently)

32. (Read pages 516-518 for more information on Molecular Clocks)

33. 17.4: Domains and Kingdoms
Eubacteria Archaea Eukarya

34. 17.4: Domains and Kingdoms
The three domains in the tree of life are Bacteria, Archaea, and Eukarya
Bacteria – includes single-celled prokaryotes in the kingdom Bacteria
cell wall contains peptidoglycan
includes bacteria that live in/on organisms, soil decomposers, disease causing bacteria (everyday bacteria)
Archaea – includes single-celled prokaryotes in the kingdom Archaea
cell wall does not contain peptidoglycan, has lipids
includes bacteria that live in extreme environments such as deep sea vents, hot geysers, salt lakes, etc.
classifying Bacteria and Archaea is difficult because they so frequently transfer genes among themselves that defining a “species” is nearly impossible; this process is just beginning and will continue as we learn more about these organisms

35. 17.4: Domains and Kingdoms
Eukarya – made up of all organisms with eukaryotic cells – distinct nucleus and membrane-bound organelles
can be single-cells, colonial, or multicellular
includes the kingdoms Protista, Plantae, Fungi, and Animalia