Lesson 8: Evolution Flashcards

Learning objective for lesson 8: Students will understand the basic theory of evolution and understand how to interpret a phylogenetic tree

1
Q

The theory of evolution was

first conceived by the British naturalist

A

Charles Darwin. Darwin’s theory explains how new
species come into existence, how organisms
become adapted to their environments, and
why specific groups of organisms share specific
traits.

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2
Q

Heritable means

A

s that
the trait is part of an organism’s genetic code
and, therefore, either will be, or (depending on
the type of reproduction) has a chance to be,
copied to the organism’s offspring

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3
Q

One source for new
heritable traits is random genetic mutation. In
order for selection to occur on any given trait,
there must be

A

variation in that trait in a

population

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4
Q

natural environments have limited
resources, and __ for these resources
permits only some organisms to successfully
reproduce before they die.

A

competition

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5
Q

The theory of evolution combines these four

basic principles of life together:

A

the differential
success of certain variations of a heritable trait,
because of competition for limited resources,
leads to the change over time (evolution) of
that trait in a population.

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6
Q

While new
traits may be introduced by random mutations,
the determination of which traits are
successfully passed on to later generations is
not random. Instead, it is based on a specific
criterion:

A

how well each trait improves an

organism’s reproductive success.

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7
Q

The competitive selective process by
which detrimental traits are competitively
discarded and advantageous traits are retained
is called

A

natural selection

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8
Q

Organisms are grouped together based on their

most recent

A

shared common ancestors

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9
Q

hadrosaurs, pachycephalosaurs, ceratopsians, ankylosaurs,

and stegosaurs are grouped together, and we call this group the

A

Ornithischia.

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10
Q

These
ornithischians and the saurischians share a
more recent ancestor with each other than they
do with all other amniotes, and we call this
group

A

Dinosauria.

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11
Q

all dinosaurs
are classified together in a group because all
dinosaurs evolved from a single species of

A

amniote tetrapod

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12
Q

A character is

A

any heritable

trait that can be described and labeled

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13
Q

shared derived character is

A

a character that is
present in two or more groups and their
common ancestor, but is not present in any
more distantly related groups

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14
Q

A shared derived

character is also called a

A

synapomorphy.

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15
Q

f ornithischians have a
special bone in the lower jaw that forms a beak,
called the

A

predentary, and no other dinosaurs
have this special beak bone. Thus, the character
of the predentary was passed on to all
ornithischians from their ancient shared
ancestor and is a synapomorphy

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16
Q

Ouranosaurus is an

A

iguanodont with a beak and
grinding teeth, hoofed toes, and long processes
on the vertebrae of the back that form a sail.

17
Q

Spinosaurus has the __ hip

A

saurischian hip

arrangement where the pubis points forwards

18
Q

Ouranosaurus has the __hip

A

ornithischian hip
arrangement where the pubis points
backwards.

19
Q

Spinosaurus and Ouranosaurus both
have a sail, but we do not consider the sail to be
__, or __,
between Spinosaurus and Ouranosaurus.

A

synapomorphy, or shared derived character

20
Q

Spinosaurus has many of the synapomorphies

of __ and __.

A

saurischians and theropods

21
Q

Ouranosaurus has many of the synapomorphies

of __ and __.

A

ornithischians and ornithopods

22
Q

Therefore,
the most likely evolutionary scenario is that the
sail in Spinosaurus evolved __of the
sail in Ouranosaurus

A

independently

23
Q

The evolution of similar traits in

two different lineages is termed

A

convergent

evolution.

24
Q

The idea that “all
other things being equal, the simplest answer is
usually the right one” is called

A

parsimony. Parsimony is also referred to as Occam’s razor. It is simpler to assume that the one character in common between Ouranosaurus and Spinosaurus (the sail) is the result of convergent evolution, than it would be to
assume that the huge number of similarities
between Ouranosaurus and iguanodonts are all
the result of convergence.

25
. The resulting arrangements look like diagrams of a “family tree” and are called
phylogenetic trees
26
Phylogenetic trees are composed of
nodes and | branches
27
A group of species that share a | common node is called a
clade. Clades can be very small (even as small as two species), or very large – there are no size limits. A clade must contain the ancestor of a group and all of its descendants. A group that does not include all of the descendants of a common ancestor is therefore not a clade.
28
Thomas Henry Huxley was a close colleague of | Charles Darwin and one of the earliest
advocates for the theory of evolution. Huxley was also the first scientist to recognize that birds evolved from dinosaurs, and he cited the newly discovered specimens of Archaeopteryx as fossils of a “missing link” between dinosaurs and birds.
29
Archaeopteryx has long wing-feathers and tail feathers just like a bird, but they also show that Archaeopteryx had
teeth, clawed fingers, and a | long series of tail vertebrae just like a dinosaur
30
Sinosauropteryx was the first
non-avian (non-bird) dinosaur to be discovered | with feathers.