1. 26.3 Shared Characters Are Used To Construct Phylogenetic Trees

2. Cladistics
Common ancestry is the most common way to classify organisms.
Clades are groupings of animals that show one common ancestor.
Clades are monophyletic, paraphyletic, or polyphyletic.
Figure 26.10

3. Comparing monophyletic, paraphyletic and polyphyletic clades

4. Shared Ancestral and shared derived characters
Shared ancestral characters are characters that are shared by many clades. (ex: vertebrae)
A derived ancestral characteristic is unique to that clade. (ex: hair)

5. Phylogenetic Trees With Proportional Branch Lengths
Pg. 555 figure 26.13
Pg. 556 figure 26.14

6. Maximum Parsimony and Maximum Likelihood
Maximum Parsimony states that the simplest explanation is one that is consistent with the facts.
Think “Occam’s Razor”
Maximum likelihood states that the tree is most likely to have produced a given set of DNA data, based on certain probability rules about how DNA sequences change over time.

7. Phylogenetic Trees as Hypotheses
A phylogenetic tree is the best attempt at explaining the relationships amongst a group of organisms.
This information needs to be remember when attempting to explain the orgins of extinct species (like dinosaurs).