1. KEY CONCEPT Organisms can be classified based on physical similarities.

2. Linnaeus’ classification system has seven levels.
Each level is included in the level above it.
Levels get increasingly specific from kingdom to species.

3. The Linnaean classification system has limitations.
Linnaeus taxonomy doesn’t account for molecular evidence.
The technology didn’t exist during Linneaus’ time.
Linnaean system based only on physical similarities.

4. Physical similarities are not always the result of close relationships.
Genetic similarities more accurately show evolutionary relationships.

5. KEY CONCEPT Modern classification is based on evolutionary relationships.

6. Cladistics is classification based on common ancestry.
Phylogeny is the evolutionary history for a group of species.
evidence from living species, fossil record, and molecular data
shown with branching tree diagrams

7. Cladistics is a common method to make evolutionary trees.
classification based on common ancestry
species placed in order that they descended from a common ancestor

8. A cladogram is an evolutionary tree made using cladistics.
A clade is a group of species that shares a common ancestor.
Each species in a clade shares some traits with the ancestor.
Each species in a clade has traits that have changed.

9. Cladograms are used to…
Organize organisms based on evolutionary relationships (phylogeny).
In other words… who is related to who and where did they come from.

10. basis of arranging species in cladogram
Derived characters are traits shared in different degrees by clade members.
FOUR LIMBS WITH DIGITS
Tetrapoda clade 1
Amniota clade 2
Reptilia clade 3
Diapsida clade 4
Archosauria clade 5
EMBRYO PROTECTED BY AMNIOTIC FLUID
OPENING IN THE SIDE OF THE SKULL
SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW
FEATHERS & TOOTHLESS BEAKS.
SKULL OPENINGS BEHIND THE EYE
DERIVED CHARACTER
basis of arranging species in cladogram
more closely related species share more derived characters
represented on cladogram as hash marks

11. Nodes represent the most recent common ancestor of a clade.
FOUR LIMBS WITH DIGITS
CLADE
Tetrapoda clade 1
Amniota clade 2
Reptilia clade 3
Diapsida clade 4
Archosauria clade 5
Clades can be identified by snipping a branch under a node.
FEATHERS AND TOOTHLESS BEAKS.
SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW
OPENING IN THE SIDE OF THE SKULL
SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
DERIVED CHARACTER
NODE

12. This diagram shows a relationship between 4 relatives
This diagram shows a relationship between 4 relatives. These relatives share a common ancestor at the root of the tree.
Note that this diagram is also a timeline. The older organism is at the bottom of the tree.
The four descendants at the top of the tree are DIFFERENT species. This is called SPECIATION.

13. Branches on the tree represent SPECIATION, the formation of a new species.
The event that causes the speciation is shown as the fork of the “V”.

14. Species B and C each have characteristics that are unique only to them.
But they also share some part of their history with species A. This shared history is the common ancestor.

15. Did humans evolve from chimps?No
What familial relationship is a good description of the relationship between chimps and humans?
Distant cousins
Are humans more highly evolved than chimps?
No, since the lineage is split, each species has evolved unique traits.
PRACTICE

16. How to Build a Cladogram