PHYLOGENIES Lecture (1-5)

Question 1

phylogeny

Answer 1

the history of evolutionary relationships among organisms

Question 2

taxon (taxa)

Answer 2

any organism, or species, or group of species that we designate or name

Question 3

monophyletic group

Answer 3

a group of organisms consisting of their MRCA and all its descendants

Question 4

clade

Answer 4

a monophyletic group

Question 5

paraphyletic group

Answer 5

a group of organisms consisting of their MRCA but excluding some of its descendants

Question 6

polyphyletic group

Answer 6

a group of organisms that excludes the MRCA

Question 7

Bifurcating trees

Answer 7

trees in which each internal node gives rise to two descendant braches

Question 8

polytomy

Answer 8

nodes have three or more descendant branches. (usually reflect uncertainty about phylogenetic relationships)

Question 9

synapomorphies

Answer 9

specific features or characters that can distinguish a monophyletic group/clade

Question 10

homologous traits

Answer 10

these that are inherited from a common ancestor

Question 11

convergence

Answer 11

traits evolved individualy not common ancestor same conditions

Question 12

sister groups

Answer 12

two clades or species that are each other’s closest relatives(two descendent taxa of a single node

Question 13

ingroup

Answer 13

the set of taxa under study

Question 14

outgroup

Answer 14

one or more taxa that fall phylogenetically outside of the group under study

Question 15

cladogram

Answer 15

only relative branching order NO meaning to branching length

Question 16

Phylogram

Answer 16

branch length is proportional to the amount of chararcter change

Question 17

Chronogram

Answer 17

branch length is proportional to time

Question 18

parsimony

Answer 18

least amount of change in character states (fewest steps)

Question 19

Parsimony-uninformative

Answer 19

1) invariant characters

2) One taxon different, others all the same

Question 20

polymorphism

Answer 20

between/during a speciation event when both character states exists in the population

Question 21

character conflict

Answer 21

when some characters support one tree and one or more support another tree

resolve by

1) add more data
2) try a different approach

Question 22

transitions

Answer 22

changes from one purine to another (A G) or
one pyrimidine to another pyrimidine (CT)

more common then tranversions

Question 23

transversions

Answer 23

changes from purine to a pyrimidne or vice versa A -> C, A->T, G->C, G->T

Question 24

synonymous substitution

Answer 24

no change in the encoded amino acid

Question 25

non-synonymous substitution

Answer 25

change in the encoded amino acid