Lecture 9 & 10- Tree Thinking

Question 1

What is phylogeny?

Answer 1

Evolutionary tree diagram showing relationships among organisms (individuals, species, groups).

Question 2

What is the tree of life?

Answer 2

Evolutionary tree uniting all species on Earth.

Question 3

What is a chronogram?

Answer 3

A type of phylogenetic tree where the lengths of the branches are scaled to represent time.

Question 4

What is a cladogram?

Answer 4

A type of phylogenetic tree where each branch represents lineages and relationships between organisms. Unscaled, doesn’t represent time.

Question 5

True or false: The nodes on phylogenetic trees can be rotated.

Answer 5

True, order of nodes doesn’t matter.

Question 6

What five things can a phylogenetic tree not be used to determine?

Answer 6

1. Older/younger species
2. More primitive/ advanced species.
3. More ancestral/ advanced species.
4. Less evolved/ more evolved species.
5. Lower/ higher species

Question 7

What three things can phylogenetic tree be used to determine?

Answer 7

1. Define monophyletic groups (true groups for classification)
2. Determine the oldest characteristic (ancestral state reconstruction).
3. Infer when lineages diverged from each other (date of common ancestry).

Question 8

What is a monophyletic group?

Answer 8

Set of species descended from one common ancestor and contains all descendants.

Question 9

What is a paraphyletic group?

Answer 9

Set of species that includes some, but not all descendants of a common ancestor.

Question 10

What is a polyphyletic group?

Answer 10

Set of species descended from two different common ancestors. Grouped by similarity, but not all descendants of a common ancestor.

Question 11

What is monophyletic versus non-monophyletic groups?

Answer 11

1. Monophyletic- contains all known descendants of a common ancestor.
2. Non-monophyletic- includes some but not all descendants of an ancestor.

Question 12

What are two examples of non-monophyletic groups?

Answer 12

1. Paraphyletic groups
2. Polyphyletic groups

Question 13

What are ancestral traits/characteristics?

Answer 13

Traits at deepest ancestral nodes on a tree (oldest traits).

Question 14

What are derived traits/characteristics?

Answer 14

Traits at the shallowest nodes or just in extant species (most recent traits).

Question 15

What is parsimony?

Answer 15

Simplest explanation is the most likely.