lec 9- phylogeny

Question 1

what is phylogeny?

Answer 1

The evolutionary history in a group (lineage) of related organisms

Question 2

what approach is used to construct phylogenies?

Answer 2

cladistics which is identifying synapomorphies

Question 3

what are synapomorphies?

Answer 3

shared features that all members of a clade share with a theoretical ancestor

Question 4

what are the two ways to draw phylogenies?

Answer 4

“combs” which was used by the founder of cladistics and the “tree” which is more favored

Question 5

what are taxon?

Answer 5

a group of organisms that share a characteristic

Question 6

what are clades?

Answer 6

group of taxons

Question 7

what is the node?

Answer 7

a branch point representing the appearance of a new shared trait (synapomorphy)

Question 8

what is a monophyletic clade?

Answer 8

a clade that includes all the descendants of an ancestor

Question 9

what is a paraphyletic clade?

Answer 9

a clade that is missing one of the ancestors descendants

Question 10

what is a polyphyletic clade?

Answer 10

missing descendants of 2+ clades

Question 11

what changes taxonomy?

Answer 11

speciation processes

Question 12

is genetic variation present among all individuals of one species?

Answer 12

yes

Question 13

where does speciation mostly happen?

Answer 13

in isolated populations

Question 14

what do cladograms summarize?

Answer 14

speciation branching events

Question 15

what are birds descended from?

Answer 15

they are descended from dinosaurs and reptiles

Question 16

what well known animal type is not a monophyletic clade?

Answer 16

fishes

Question 17

what is one synapomorphy all carnivores share?

Answer 17

carnassial teeth

Question 18

on what basis of analysis are phylogenies made?

Answer 18

comparing shared traits with an outgroup and other members

Question 19

what is the parsimony rule?

Answer 19

the tree that needs the fewer steps (traits) to achieve the result are most likely true

Question 20

are hyena cats and civets all related?

Answer 20

yes

Question 21

are cats and hyenas sister taxa?

Answer 21

yes

Question 22

what is homeoplasy?

Answer 22

character state similarity not due to common descent

Question 23

what is convergent evolution?

Answer 23

independant evolution of similar traits in different clades

Question 24

what are evolutionary reversals?

Answer 24

reversion back to an ancestral character state

Question 25

what are the differences between legless lizards and snakes?

Answer 25

snakes don’t have eye lids, hinged lower jaw, movable belly scales and more

Question 26

when was the discovery of a fossil snake with 4 legs done?

Answer 26

in 2012, 120 Ma, early cretaceous of brazil

Question 27

what are spurs?

Answer 27

vestigial hind leg bones in living boas