Phylogenetic/Molecular Evolution (W4-L1)

Question 1

Plesiomorphy

Answer 1

Primitive or ancestral character state

Question 2

Symplesiomorphy

Answer 2

Ancestral homology, homologous trait retained from the ancestor of the group

Question 3

Apomoprphy

Answer 3

Derived character state

Question 4

Sister group/sibling species

Answer 4

Closest relative on the phylogenetic tree

Question 5

Monophyletic group

Answer 5

refers to everyone in the clade or node

Question 6

Paraphyletic Group

Answer 6

refers to specific species in the same clade, but not all species in the clade

Question 7

Polyphyletic group

Answer 7

species completely separate from one another, often do not have a common ancestor, in different clades

Question 8

Character vs Character state

Answer 8

Character: general category for which species manifest different Character states

ex. Character: wing color, Character state: blue wings

Question 9

Autapomorphy

Answer 9

Unique derived character state: A derived trait unique to one species in the group of study.

Question 10

Synapomorphy

Answer 10

Shared, derived character state

Question 11

Three ways to determine ancestral character

Answer 11

1. out-group: ancestral, closely related but not within the same group
2. Embryology: characters expressed early in development are ancestral relative to ones expressed late in development
3. Fossil evidence: characters found early in fossil record are ancestral

Question 12

What is the study of Molecular Evolution?

Answer 12

The use of different organisms to study the evolution of DNA an protein sequences (i.e. how and when did genes originate)

Question 13

What is mutation rate in molecular evolution?

Answer 13

rate per generation at which an error in replication occurs

Question 14

What is the substitution rate in molecular evolution?

Answer 14

the rate per year at which a mutation fixes in a population

ex. rate at which a mutation reaches 100%

Question 15

What is Neutral Theory?

Answer 15

Under neutrality, the probability of a new mutation spreading in a population and fixing is 1/2N

where 2N(mew) = Number of new mutation entering a population

(mew) = mutation rate

conclude fitness effects are a result of mutation and genetic drift only

Question 16

Why is selection weaker at the molecular level?

Answer 16

• Not all DNA translates into protein
• Not all protein variation translates into phenotypic variation
• Not all phenotypic variation translates into fitness differences

Question 17

How did Kimura and Jukes develop Neutral Theory?

Answer 17

• sequence evolution in mammals is rapid: 1 amino acid per 1.8 year
• such a high mutation frequency suggests the majority of substitution have no fitness effects
• conclude fitness effects are a result of mutation and genetic drift only