cycle 9

Question 1

phylogenetic tree

Answer 1

a hypothesis describing the evolutionary relationships of species or any group or organisms (shows their evolutionary history)

Question 2

tips/leaves

Answer 2

species or groups of organisms existing in the present (extant)

Question 3

tip labels

Answer 3

names of species, letters

Question 4

branches

Answer 4

lines to a new species

Question 5

nodes

Answer 5

intersection of branches, represents a common ancestor

Question 6

bifurcates

Answer 6

splits in two

Question 7

monophyletic clade

Answer 7

all descendants of a common ancestor

Question 8

outgroup

Answer 8

furthest from all other species, evolved from the oldest node

Question 9

what does the length of the branches represent?

Answer 9

time, molecular distance

Question 10

root

Answer 10

oldest, earliest node

Question 11

derived traits

Answer 11

evolved after the most recent common ancestor of a group

Question 12

ancestral traits

Answer 12

evolved before the most recent common ancestor of a group (traits can be lost, not all members have the trait)

Question 13

parsimony

Answer 13

the simplest explanation is most likely (fewest evolutionary changes), used when constructing trees

Question 14

shared traits

Answer 14

shared by at least 2 members of the group, not unique

Question 15

synapomorphies

Answer 15

shared, derived traits (useful)

Question 16

how to determine which traits are ancestral/derived?

Answer 16

use an outgroup (close relative known to have branched off earlier, use parsimony)

Question 17

divergence

Answer 17

misleading dissimilarity despite close evolutionary relationship

Question 18

how are organisms ideally classified?

Answer 18

based on monophyletic groups (many traditionally recognized groups are not monophyletic)

Question 19

are unique traits useful in building a tree?

Answer 19

no

Question 20

how do we tell if the same trait is homologous or due to convergence?

Answer 20

• structural/developmental similarity is more informative than superficial similarity
• build tree using other traits
• use molecular data to determine evolutionary relationships

Question 21

molecular phylogenetics

Answer 21

using molecular differences to build evolutionary trees