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BIO 303 > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

What is Tiktaalik?

A

transitional fossil between fish and tetrapods

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2
Q

Define Phylogeny:

A

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

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3
Q

Define tips:

A

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

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4
Q

Branches

A

Lineages evolving through time between successive speciation events.

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5
Q

Nodes

A

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

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6
Q

Internal Nodes

A

Nodes within a phylogeny representing ancestral populations or species.

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7
Q

Clade

A

An organism and all of its descendants.

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8
Q

Monophyletic

A

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

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9
Q

Characters

A

Heritable aspects of organisms that can be compared across taxa.

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10
Q

Taxon (taxa)

A

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

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11
Q

Synapomorphy

A

A shared derived character.

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12
Q

Shared derived character

A

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

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13
Q

Cladistics

A

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

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14
Q

Homoplasy

A

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

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15
Q

Convergent Evolution

A

The independent origin of similar traits in separate evolutionary lineages.

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16
Q

Evolutionary Reversal

A

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

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17
Q

Exaptation

A

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

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18
Q

Australopithecine

A

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

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19
Q

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

A

T

20
Q

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

A

Seed.

21
Q

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

A

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

22
Q

What was Linnaeus’ system built on?

A

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

23
Q

T or F: Clades are monophyletic groups

A

true

24
Q

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

A

Reptilia

25
Q

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

A

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

26
Q

What would the most parsimonious tree be?

A

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

27
Q

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

A

NO

28
Q

What can lead to homoplasy?

A

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.

29
Q

What are coelacanth fins homologous to?

A

Coelacanth fins are homologous to tetrapod forelimb

30
Q

How did the tetrapod arm develop?

A

the humerus and wrist bones kept evolving.

31
Q

what reptilian bones are homologous to mammalian inner ear bones?

A

Bones that once were connected to the jaw.

32
Q

True or False: Feathers evolved before flight.

A

True

33
Q

What were feathers originally used for?

A

Attracting mates via color and visual representation

34
Q

What traits needed to evolve from African apes to humans?

A

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

35
Q

Explain the transition to bipedalism:

A

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

36
Q

Ardipithecus traits:

A

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

37
Q

What species made the 1.5 myo footprints?

A

Tracks made by Australopithecus afarensis (1.5 myo)

38
Q

Why did the trait for walking upright succeed?

A

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

39
Q

Homo Erectus

A

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

40
Q

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

A

T

41
Q

What is our understanding of human evolution based on?

A

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

42
Q

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

A
  • 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.
43
Q

What homologies do Tiktaalik and Acanthostega share?

A

weight-bearing elbows and lungs

44
Q

Why are bird feathers considered an exaptation?

A

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

45
Q

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

A

Opposable big toes.

46
Q

What clade do tetrapods belong in?

A

Lobe-fins, which includes coelacanths and lungfishes.

47
Q

Why do scientists classify humans as therians?

A
  • 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.

BIO 303 (4 decks)

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