A tree places A and B as sisters, with C outside their pair. The most recent common ancestor of all three taxa has state 2. A and B have state 3; C has state 2. What is the minimum number of changes for this character?

Whale flipper bones and human arm bones were inherited from a common ancestor. Bird and insect wings evolved separately as flight structures. Which conclusion matches this evidence?

• Both comparisons show homology because the features have similar uses.
• The bones show homology; the wings show separate evolutionary origins.
• Both comparisons show convergence because the features have different structures.

Under equal-weight parsimony, gains count as changes but losses do not.

An ancestor has exactly three descendant lineages. Which proposed group is a clade containing that ancestor?

• The ancestor and two descendants, leaving out the third lineage.
• The ancestor and three similar but unrelated lineages.
• The ancestor and every one of its three descendant lineages.

A state was present in the ancestor of a studied group and remains in every sampled member. What does this state tell you about branching within that group?

• It cannot distinguish the branching order within this sampled group.
• It identifies the earliest split within the group.
• It identifies the closest pair because every member retains the ancestral state.

Backbones occur in mammals and other vertebrates. Can backbone presence alone identify mammals as a distinct subgroup?

• Yes; inheritance makes the trait unique to mammals.
• No; backbone presence also occurs in other vertebrate groups.
• Yes; a trait shared throughout mammals must distinguish them from every other vertebrate.

The ancestor of A, B and C had a tail. A retains it; B and C lack it. Which statement about tail absence is supported?

• It is ancestral because the common ancestor had a tail.
• It proves B and C are sisters, even if their tails were lost independently.
• It is a derived state that can support B and C as a group.

For two equally weighted characters, Tree P needs minimum counts of 2 and 3 changes. Tree Q needs 4 and 2. Which tree has the lower total, and what is that total?

• Tree P: a total of 5 changes.
• Tree Q: a total of 6 changes.
• A tie: a total of 6 changes.