1. Classification Notes

2. Humans like to group!
We place things into groups in order to understand relationships.
Aristotle first classified living things in 350 BC.

3. Aristotle’s ideas were accepted for 2,000 years!
Animals were grouped by habitat & behavior.
Plants were grouped by size and structure.

4. ANIMALS
LAND
AIR
WATER

5. PLANTS
HERB
SHRUB
TREE

6. Taxonomy Taxonomy: the science of grouping organisms
Taxa: Organisms within a particular group
In 1735 Carolus Linnaeus devised a system based upon structural characteristics.

7. Linnaeus created seven Levels of Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
King
Phillip
Came
Over
For
Green
Spinach
General
Specific

8. Linnaeus created a method for naming organisms
Binomial nomenclature: a two-word system of naming organisms
Uses the genus + species names
Example: Humans = Homo sapiens or Homo sapiens
Always italicized or underlined
Genus capitalized
Species with lower case

9. Linnaeus’ System
Groups similar organisms
Provides a standard system for naming organisms

10. New technologies can change the way we view science…
Domains have been placed above kingdoms (1996).

11. Three Domains of Life Domain Bacteria Domain Archaea Domain Eukarya
- True bacteria; prokaryotic
Domain Archaea
- Ancient bacteria; prokaryotic
Domain Eukarya
- Eukaryotic; plants, animals, fungi, & protist

12. Cladistics
A phylogeny, or evolutionary tree, represents the evolutionary relationships among a set of organisms or groups of organisms, called taxa (singular: taxon).

13. The tips of the tree represent groups of descendent taxa (often species) and the nodes on the tree represent the common ancestors of those descendents. Two descendents that split from the same node are called sister groups.

14. Evolutionary trees depict clades
Evolutionary trees depict clades. A clade is a group of organisms that includes an ancestor and all descendents of that ancestor. You can think of a clade as a branch on the tree of life.

15. Cladistics is a method of hypothesizing relationships among organisms
Cladistics is a method of hypothesizing relationships among organisms. The basis of a cladistic analysis is data on the characteristics, or traits, of the organisms in which we are interested. These characters could be anatomical and physiological characteristics, behaviors, or genetic sequences.

16. Activity
Cladistics of Vehicles

17. Example
Choose the taxa. You decide to study the major clades of vertebrates.
Determine the characters. After studying the vertebrates, you select a set of traits, which seem to be homologies, and build the following data table to record your observations.

19. 3. Determine the polarity of characters
3. Determine the polarity of characters. From studying fossils and outgroups closely related to the vertebrate clade, you hypothesize that the ancestor of vertebrates had none of these features.

20. 4. Group taxa by synapomorphies
4. Group taxa by synapomorphies. Since we have a good idea of what the ancestral characters are, this is not so hard. We might start out by examining the egg character. We focus in on the group of lineages that share the synapomorphic form of this character, an amniotic egg, and hypothesize that they form a clade.

22. 5. Work out conflicts that arise. There are no conflicts here
5. Work out conflicts that arise. There are no conflicts here. Every group is a subset of another group

23. 6. Build your tree. Based on the groupings above, you produce this tree: