Chapter 8

Question 1

Apomorphy

Answer 1

Derived characteristic

Question 2

Plesiomorphy

Answer 2

Preexisting/ancestral characteristic

Question 3

Synapomorphy

Answer 3

Derived characteristic shared by multiple lineages

Question 4

Paraphyletic

Answer 4

A common ancestor and all but one of its descendants

Question 5

Polyphyletic

Answer 5

Some descendants (excluding more than one), but not including the common ancestor

Question 6

Polytomy

Answer 6

Three-way split (three branches)

Question 7

Convergent/Homoplasy evolution

Answer 7

Similar characteristics appearing in different lineages

Question 8

Reversal

Answer 8

Loss of derived traits

Question 9

Homoplasy

Answer 9

Similarity in character states due to convergence or reversal

Question 10

Likelihood

Answer 10

Probability of the data given in a tree, it’s branch lengths, and a model of evolution

Question 11

Molecular clock

Answer 11

Addressing questions about timing by analyzing molecular traits that change at a steady state

Question 12

Neutral mutations

Answer 12

Change in an individuals DNA, but not their phenotype. Caused by genetic drift

Question 13

Transitions

Answer 13

Evolutionary modifications

Question 14

Root

Answer 14

The common ancestor of all descendants

Question 15

Node

Answer 15

The common ancestor of the preceding descendants

Question 16

Sister species

Answer 16

Each other’s closest relatives

Question 17

Clade

Answer 17

A monophyletic group, an ancestor and all of its descendants

Question 18

Explain one source of uncertainty in phylogenetic tree construction

Answer 18

Similar adaptations can evolve independently, known as convergent evolution.

Question 19

Why are parsimonious trees not necessarily correct? Why, then, do we use parsimony?

Answer 19

They are not necessarily correct because evolution does not necessarily work in the fewest evolutionary changes of characteristics (Ockham’s razor). We still use it because it allows us to still make inferences when evidence is limited, and it can be justified as a statistical estimator of unknown phylogeny.