3 - Phylogeny 1

Question 1

What is phylogenetics?

Answer 1

The study of how species are related to each other.

Question 2

What are cladistics and phenetics?

Answer 2

Two approaches to studying relationships between species.

Question 3

What does cladistics focus on?

Answer 3

Shared derived characters and evolutionary relationships.

Question 4

What is phenetics based on?

Answer 4

Overall similarity regardless of evolutionary history.

Question 5

What is parsimony in phylogeny?

Answer 5

Seeking the simplest explanation with the fewest changes.

Question 6

What are synapomorphies?

Answer 6

Traits shared by a group’s common ancestor and descendants.

Question 7

How are phylogenetic trees estimated?

Answer 7

By minimizing the number of character changes (parsimony).

Question 8

What is homoplasy?

Answer 8

Character similarity not due to common descent.

Question 9

What can cause homoplasy?

Answer 9

Convergent evolution or evolutionary reversals.

Question 10

How can homoplasy affect reconstructions?

Answer 10

It can mislead phylogenetic reconstructions.

Question 11

What are monophyletic groups?

Answer 11

Ancestor and all of its descendants in a tree.

Question 12

What are outgroups used for?

Answer 12

To determine ancestral and derived character states.

Question 13

step 1 in tree estimation?

Answer 13

Choosing synapomorphies for clades.

Question 14

What does step 2 involve?

Answer 14

Using outgroups to determine ancestral and derived states.

Question 15

Step 3 tree estimation

Answer 15

Finding characters shared by two taxa.

Question 16

step 4 of tree estimation?

Answer 16

Expanding clades by adding characters with state “1”.

Question 17

What does a polytomy indicate?

Answer 17

Uncertainty in relationships in a phylogenetic tree.

Question 18

Why can’t all traits be relied upon?

Answer 18

Some traits may appear similar due to homoplasy.

Question 19

What is a monophyly criterion for?

Answer 19

Higher taxa in phylogenetics.

Question 20

What do modern cladistic classifications aim for?

Answer 20

Reflecting evolutionary history accurately.

Question 21

What is the significance of transitional fossils like Tiktaalik?

Answer 21

Providing insights into evolutionary transitions.

Question 22

What evidence helped predict Tiktaalik’s location?

Answer 22

Upper-Devonian rocks in Northern Canada.

Question 23

What does Tiktaalik represent?

Answer 23

A transitional form between fish and tetrapods.

Question 24

What are some homologous traits of Tiktaalik with tetrapods?

Answer 24

Wrist and neck structures.

Question 25

What is the main focus of phylogenetic reconstructions?

Answer 25

Using shared derived characters or synapomorphies.

Question 26

Cladistics

Answer 26

is a way to group organisms based on their shared evolutionary history. It uses shared unique traits to build family trees.

Question 27

Phenetics

Answer 27

classifies organisms by how similar they look or their genetic makeup, without worrying about their family history.

Question 28

Shared derived characters

Answer 28

are special traits that groups of organisms share because they came from a common ancestor.

Question 29

Parsimony

Answer 29

is the idea that the simplest explanation or family tree with the fewest changes is usually the best.

Question 30

Phylogeny estimation

Answer 30

is figuring out how different organisms are related to each other in their family tree.