Chapter 4

Question 1

What is Tiktaalik?

Answer 1

transitional fossil between fish and tetrapods

Question 2

Define Phylogeny:

Answer 2

A visual representation of the evolutionary history of populations, genes, or species.

Question 3

Define tips:

Answer 3

terminal ends of an evolutionary tree, representing species, molecules, or populations being compared.

Question 4

Branches

Answer 4

Lineages evolving through time between successive speciation events.

Question 5

Nodes

Answer 5

a point in a phylogeny where a lineage splits( a speciation event)

Question 6

Internal Nodes

Answer 6

Nodes within a phylogeny representing ancestral populations or species.

Question 7

Clade

Answer 7

An organism and all of its descendants.

Question 8

Monophyletic

Answer 8

a group made of up of an organism and all its descendants.

Question 9

Characters

Answer 9

Heritable aspects of organisms that can be compared across taxa.

Question 10

Taxon (taxa)

Answer 10

A group of organisms that a taxonomist judges to be a taxonomic unit, such as a species or order.

Question 11

Synapomorphy

Answer 11

A shared derived character.

Question 12

Shared derived character

Answer 12

one that evolved in the immediate common ancestor of a clade and was inherited by all its descendants.

Question 13

Cladistics

Answer 13

Phylogenetic methods that construct trees by grouping taxa into nested hierarchies (clades) according to their shared derived characters(synapomorphies).

Question 14

Homoplasy

Answer 14

Character state similarity not due to shared descent. Produced by convergent evolution or evolutionary reversal.

Question 15

Convergent Evolution

Answer 15

The independent origin of similar traits in separate evolutionary lineages.

Question 16

Evolutionary Reversal

Answer 16

the reversion of a derived character state to its ancestral state.

Question 17

Exaptation

Answer 17

A trait that originates performing one function, and which is later co-opted for a new function.

Question 18

Australopithecine

Answer 18

any of a genus (Australopithecus) of extinct southern and eastern African hominids that include gracile and robust forms with near-human dentition and a relatively small brain

Question 19

T or F: No current living species is ancestral to any other

Answer 19

T

Question 20

Which term is not associated with tree-like depictions of evolutionary histories known as phylogenies?: Node, Seed, Branch, Root

Answer 20

Seed.

Question 21

If you were looking at a phylogeny of living bird species, where could you find the name of a species of non-theropod dinosaur?

Answer 21

At the tip of a branch, as an out group or at the root of the tree.

Question 22

What was Linnaeus’ system built on?

Answer 22

an understanding of structural similarities that was relatively basic compared with the tools of scientists today.

Question 23

T or F: Clades are monophyletic groups

Answer 23

true

Question 24

Which of the following is not a monophyletic group?: clade, reptilia, aves, amphibia

Answer 24

Reptilia

Question 25

Based on your understanding of Carl Linnaeus' classification system, how would you treat his conclusions?

Answer 25

Classification scheme could be used as a starting point for examining taxonomic relationships.

Question 26

What would the most parsimonious tree be?

Answer 26

The most parsimonious tree is the one that requires the fewest evolutionary transitions from 0 to 1.

Question 27

Is the ability to swim in dolphins and sharks a synapomorphy?

Answer 27

NO

Question 28

What can lead to homoplasy?

Answer 28

The reversion of a derived character state to its ancestral state, the independent origin of similar gratis in separate lineages, evolution of wings in both birds and bats.

Question 29

What are coelacanth fins homologous to?

Answer 29

Coelacanth fins are homologous to tetrapod forelimb

Question 30

How did the tetrapod arm develop?

Answer 30

the humerus and wrist bones kept evolving.

Question 31

what reptilian bones are homologous to mammalian inner ear bones?

Answer 31

Bones that once were connected to the jaw.

Question 32

True or False: Feathers evolved before flight.

Answer 32

True

Question 33

What were feathers originally used for?

Answer 33

Attracting mates via color and visual representation

Question 34

What traits needed to evolve from African apes to humans?

Answer 34

Fossil record should document transition to to unique human traits – Bipedality – Larger brain size – Smaller canine teeth

Question 35

Explain the transition to bipedalism:

Answer 35

Appears to have evolved before larger brain – Position of foramen magnum – Weight bearing stance – Short, stiff toes

Question 36

Ardipithecus traits:

Answer 36

Small head, large jaw, anchors for muscles in pelvis, four short toes. May have been bipedal.

Question 37

What species made the 1.5 myo footprints?

Answer 37

Tracks made by Australopithecus afarensis (1.5 myo)

Question 38

Why did the trait for walking upright succeed?

Answer 38

They might have lived in more open woodlands and needed to walk upright to obtain food.

Question 39

Homo Erectus

Answer 39

1.9 mya, had a flatter face, legs well adapted to walking and maybe running. Larger brain as well 600-900 cc.

Question 40

T or F: Living members of a clade may not reliably indicate origins of synapomorphies

Answer 40

T

Question 41

What is our understanding of human evolution based on?

Answer 41

Our current understanding of human evolution is based on many specimens of 20 different species

Question 42

How does including fossils in phylogenies of extant taxa affect the conclusions scientists can draw?

Answer 42

- Including fossils can change the hypothesis generated by the phylogeny - Including fossils can define the timing of branching events - including fossils can affect the understanding of common ancestors - including fossils can generate new questions about clades.

Question 43

What homologies do Tiktaalik and Acanthostega share?

Answer 43

weight-bearing elbows and lungs

Question 44

Why are bird feathers considered an exaptation?

Answer 44

they first evolved under different conditions than those under which they are currently found.

Question 45

Which choice below is NOT evidence that Ardipithecus radius spent much of its time walking on two legs?

Answer 45

Opposable big toes.

Question 46

What clade do tetrapods belong in?

Answer 46

Lobe-fins, which includes coelacanths and lungfishes.

Question 47

Why do scientists classify humans as therians?

Answer 47

- middle ear bones of humans are not fused to the jaw, they are separate. - humans do not lay eggs - humans share more synapomorphies with mammalian fossil Liaoconodon.