Phylogenetic Trees

Question 1

What is a phylogenetic tree?

Answer 1

• hypothesized evolutionary relationship among species
• not fact , can’t know relationship without certainty
• always tested / revised

Question 2

What is the tip of the tree?

Answer 2

Taxa: name can represent pop, species, larger groups , dna

Question 3

Branches in a tree?

3

Answer 3

• species/ pop/ gene through time
• independent evolutionary lineage from ancestor to descendent
• Length branch meaningless

Question 4

Internal nodes in trees

Answer 4

• ancestral pop that split into two or more decedents groups
• a speciation event

Question 5

Root in a tree

Answer 5

Most ancestral branch in tree

Question 6

Character states ( marks in a tree)

Answer 6

Where think traits arose/got lost in evolutionary history

Question 7

What is a monophyletic groups

2

Answer 7

An ancestor and all decedents (include internal nodes)

• reflect evolutionary connections

Question 8

What’s a paraphyletic groups

Answer 8

Include common ancestor and some (not all decedents )

• eg pair pants without a leg

Question 9

Polyphyletic groups?

Answer 9

Collection organisms where most recents common ancestor not included

Question 10

What data can be used to build a tree?

7

Answer 10

Morphological, 
genetic , 
developmental , 
Physiological 
Molecular 
Behavioral 

• homologous trait to indicate relatedness

Question 11

Homologous traits

Answer 11

Traits from shared ancestor

whale and human hands

Question 12

Homologous ancestral trait

Answer 12

Inherited from distant ancestor

Question 13

Homologous derived traits

Answer 13

Appear (mutation ) in most recent ancestor

Question 14

Synamorphies

3

Answer 14

Shred derive characteristics

More closely related species share more synapomorphies

Unique dna = synapomorphies

Question 15

Analogous traits (homoplasies )

2

Answer 15

Traits look same but diff ancestor

• due to convergent evolution

Question 16

Convergent evolution

Answer 16

• adaptation to sim environment evolve similar traits but diff ancestors

Question 17

What is principal of parsimony

2

Answer 17

• Simplest explanation

- most likely true

Question 18

What are 5 trees misconceptions?

State them correctly though

Answer 18

1) proximity tips don’t indicate relatedness
2) degree relatedness not indicated by member nodes separating them
3) some taxa at tips are not ancestor to other on tree
4) taxa at end not more evolved then rest
5) evolutionary change don’t always occur at nodes in