Lecture 3

Question 1

systematists

Answer 1

those who engage in systematics

Question 2

changes in systematics since 1960s

Answer 2

focus has switched from adding new taxa to methods for determining relatedness among taxa, desire for evolutionarily informative classifications means that old taxonomies must be changed

Question 3

molecular systematics

Answer 3

using proteins, DNA, and RNA, accelerated rate of taxonomic change

Question 4

stratigraphy

Answer 4

temporal order in which fossils occur

Question 5

Willi Hennig

Answer 5

German entomologist, invented Hennigian systematics in the 1950s

Question 6

purpose of Hennigian systematics

Answer 6

objective and transparent, classifications that reflect ancestor-descendant relationships

Question 7

clade

Answer 7

a group of organisms with shared, derived characteristics

Question 8

Hennig’s approach aka

Answer 8

cladistics or phylogenetic systematics

Question 9

cladogram

Answer 9

branching diagram showing these hypothesized relationships

Question 10

length of branches on cladogram

Answer 10

do not mean anything

Question 11

node/branching point

Answer 11

where lineages diverge (on cladogram)

Question 12

dichotomy

Answer 12

fully resolved split into two taxa

Question 13

polytomy

Answer 13

unresolved pattern of divergence

Question 14

phylogenetic hypothesis

Answer 14

created by systematists using information such as morphology, behaviour, DNA sequences, and biochemistry

Question 15

ingroup

Answer 15

the group whose relationships they are interested in untangling

Question 16

character

Answer 16

each type of structure, behaviour, etc

Question 17

state

Answer 17

manifestation of character in a particular taxon

Question 18

outgroups

Answer 18

taxa related to the ingroup, but diverged at an earlier time

Question 19

parsimony

Answer 19

goal of a cladistic analysis is to construct a set of nested relationships that minimizes the number of times a character has to change states

Question 20

principle of parsimony aka occam’s razor

Answer 20

if one must postulate a number of unknowable events, the best hypothesis is the one requiring the fewest postulates

Question 21

outgroup state

Answer 21

set at ‘0’ and considered to be ancestral (original)

Question 22

derived state

Answer 22

different from that in outgroup, coded as 1

Question 23

character-state polarization

Answer 23

direction of changes in the character is decided

Question 24

sister taxa

Answer 24

closest relative in a clade

Question 25

synapomorphy

Answer 25

shared derived state (only state useful for reconstructing phylogenetic relationships)

Question 26

symplesiomorphy

Answer 26

shared ancestral state

Question 27

autapomorphy

Answer 27

unique derived character state present in only one taxon

Question 28

homologous

Answer 28

same character state same origin

Question 29

analogous/homoplasious/convergent

Answer 29

character state appears same, evolved independently

Question 30

molecular phylogenetics

Answer 30

matching of bases in selected gene sequences

Question 31

phylogram

Answer 31

trees in which numbers of differences between taxa are represented by branch lengths

Question 32

molecular clock

Answer 32

assumption of relatively constant rate of mutation accumulation allow branch lengths that may reflect time since divergence, requires calibration through fossil data

Question 33

maximum parsimony in molecular phylogenetics

Answer 33

choose the tree that requires the fewest total number of base pair changes

Question 34

maximum likelihood in molecular phylogenetics

Answer 34

selecting the best tree involves incorporating ‘rules’ about how DNA is most likely to change (ex. silent mutations more likely)

Question 35

monophyletic

Answer 35

true clades - contain a common ancestor and all of its descendants

Question 36

polyphyletic

Answer 36

taxa that do not share recent ancestor grouped together

Question 37

paraphyletic

Answer 37

result of the removal of taxa that are highly divergent from the rest of their clade