Lecture 10: Phylogenetic Trees

Question 1

common descent

Answer 1

-all living organisms are the descendants of a signle common ancestor

Question 2

phylogeny

Answer 2

-an ancestral population that diverged into 2 new species

Question 3

branches

Answer 3

• represent genetic change

- the farther away a diagnal moves the more different the 2 organisms are

Question 4

nodes

Answer 4

• species in the past that’s an ancestor to all organisms that branch out from that point
• a split after a node represents a speciation event

Question 5

tips

Answer 5

• represent the species that are present in the current time

- organismsin the present are all equally evolved

Question 6

tips

Answer 6

• represent the species that are present in the current time

- organismsin the present are all equally evolved

Question 7

great chain of being

Answer 7

-a vertical construct which places all of creation in an ordered list from greatest to lowest

Question 8

why is a phylogeny different than a “great chain”?

Answer 8

• a phylogeny isn’t a vertical chain of complexity/importance
• tips of a phylogeny are equally successful bc we measure success by being around therefore equally evolved

Question 9

sister taxa

Answer 9

-the 2 organisms with the most recently shared common ancestor

Question 10

outgroup

Answer 10

-the most closely related organism that’s not within the related group and evolved before the group branched off

Question 11

how can you make phylogenic trees with DNA data?

Answer 11

-by looking at the bases in genetic sequences and comparing them to see which have the most bases in common

Question 12

parisomony

Answer 12

-the phylogenetic tree with the least number of changes is most likely to be true

Question 13

do mutations in a single species give more or less info for phylogeny building than mutations in multiple species?

Answer 13

• less info, it just tells us that they’re not the same

- one species doesn’t tell us anything about shared ancestry

Question 14

how are non-DNA traits used for making phylogenies?

Answer 14

• shared morphology
• developmental patterns
• behavioral patterns
• paleontological data

Question 15

homoplasious/convergent traits

Answer 15

-independent evolution of similar features from different ancestral traits

Question 16

homologous/derived traits

Answer 16

-shared traits that are passed on from a common ancestor

Question 17

analogy

Answer 17

• aka homoplasy

- similar structures found in 2 or more groups of organisms but with separate independent evolutionary origins

Question 18

MRCA

Answer 18

• aka most recent common ancestor

- the species at the nose that is the highest up (most recent) that unites all species in a given group

Question 19

UCA

Answer 19

• aka univeral common ancestor

- the oldest species in the tree diagram that every species younger (or above it) is related to

Question 20

LUCA

Answer 20

• aka last universal common ancestor
• the first organism to give rise to all other life
• appears based off of the entire tree of life

Question 21

how can you make a phylogenic tree with trait tables?

Answer 21

-animal with the least amount of traits is always lowest in phylogenic trees

Question 22

monophyletic

Answer 22

-a group containing its MRCA and all descendants of that MRCA

Question 23

paraphyletic

Answer 23

• a group containing its MRCA, but not all descendents of that MRCA
• dinosaurs are in this category bc they include birds

Question 24

why are birds dinosaurs? are they still birds?

Answer 24

-they consider them being dinosaurs that survived the K-T extinction

Question 25

why doesnt taxonomy always reflect phylogeny?

Answer 25

-we made the names of animals without seeing the phylogenies

Question 26

prokaryote

Answer 26

-single celled organism that lack a nucleus