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4 Mechanisms of Evolution > 25 The History of Life on Earth > Flashcards

25 The History of Life on Earth Flashcards

1
Q

What is macroevolution?

A

The broad pattern of evolution above the species level.

Therefore it deals more with questions such as how did life move from the water to land.

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2
Q

What is the general consensus on how life emerged from abiotic components?

A

It is believed to have happened in 4 stages:

  1. The abiotic (nonliving) synthesis of small organic mol- ecules, such as amino acids and nitrogenous bases
  2. The joining of these small molecules into macromolecules, such as proteins and nucleic acids
  3. The packaging of these molecules into protocells, droplets with membranes that maintained an internal chemistry different from that of their surroundings.
  4. The origin of self-replicating molecules that eventually made inheritance possible
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3
Q

What is an example of a set of conditions where the synthesis of amino acids could occur?

A

Many were found during a stimulated volcanic eruption

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4
Q

What are the basic forms of amino acids and how do they differ? (not acidic, basic etc.)

A

L Isomer and D isomer forms

Life on earth uses on the L form

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5
Q

What does ‘L isomer’ refer to in terms of amino acids?

A

One of two forms (L isomer and D isomer) of amino acids

Life on earth uses only L isomer

Thus the presence of the D isomer form in meteorites shows that amino acids can be synthesised abiotically.

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6
Q

What were primitive cells called?

A

Protocells

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7
Q

What are protocells?

A

The first primitive cells.

They existed as vesicles that spontaneously formed from hydrophobic substances to form a basic lipid bilayer.

They had clumps of clay called ‘montmorillonite’ around which chemicals concentrated and thus the rate of reaction increased.

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8
Q

What came first: RNA or DNA?

A

Probably RNA

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9
Q

What is ‘montmorillonite’?

A

A soft mineral clay that was abundant when life on earn began so was likely part of the first ‘protocol.’

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10
Q

What are the key sources of information about the history of life on earth?

A
  • The fossil record

- Genetic analysis

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11
Q

When did the first unicellular eukaryote paper?

A

1,500 mya

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12
Q

What does ‘MYA’ refer to in the context of history?

A

Million years ago - therefore 1000 mya is a billion years ago

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13
Q

When where plesiosaurs around n earth?

A

200 to 65.5 mya

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14
Q

What is a common methods to determine the age of rocks and organic samples?

A

Radiometric dating

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15
Q

What is radiometric dating?

A

A method of determining the age of something based on its concentration of isotopes.

It works on the assumption that when an organism dies it will take in no new carbon. Any radioactive carbon that remains inside will slowly decay into stable carbon.

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16
Q

What it called when the age of something is determined by looking at isotopes?

A

Radiometric dating

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17
Q

What is a common isotope looked at when performing radiometric dating?

A

Carbon-14 which eventually becomes carbon-12

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18
Q

Some specimens are so old that they have minute amounts of carbon-12 present. How are they dated?

A

Organisms do not accumulate the radioactive uranium-238 However the rocks around them do.

Therefore by measuring the ratio of uranium-238 to U-235 in the surrounding rocks the age of the sample can be deduced.

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19
Q

What is the sequence in the evolution of mammals?

A

Synapsid → Therapsid → Early cynodont → Later cynodont → Very late cynodont → Modern Mammals

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20
Q

In the evolution of mammals, when did Snapsids first appear?

A

300 mya

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21
Q

In the evolution of mammals, when did Therapsid first appear?

A

280 mya

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22
Q

In the evolution of mammals, when did Early cynodont first appear?

A

260 mya

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23
Q

In the evolution of mammals, when did Later cynodont first appear?

A

220 mya

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24
Q

In the evolution of mammals, when did Very late cynodont first appear?

A

195 mya

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25
Q

In the evolution of mammals, what are synapsids?

A

They have multiple bones in the lower jaw and single-pointed teeth.

The jaw hinge was formed by the articular and quadrate bones. Synapsids also had an opening called the temporal fenestra behind the eye socket. Powerful cheek muscles for closing the jaws probably passed through the temporal fenestra.

Over time, this opening enlarged and moved in front of the hinge between the lower and upper jaws, thereby increasing the power

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26
Q

In the evolution of mammals, therapsids?

A

Therapsids had large dentary bones, long faces, and the first examples of specialized teeth, large canines. These trends continued in a group of therapsids called cynodonts.

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27
Q

In the evolution of mammals, what are Early cynodonts?

A

In early cynodont therapsids, the dentary was the largest bone in the lower jaw, the temporal fenestra was large and positioned forward of the jaw hinge, and teeth with several cusps first appeared.

As in earlier synapsids, the jaw had an articular-quadrate hinge.

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28
Q

In the evolution of mammals, what are Later cynodonts?

A

Later cynodonts had teeth with complex cusp patterns and their lower and upper jaws hinged in two locations: They retained the original articular-quadrate hinge and formed a new, second hinge between the dentary and squamosal bones.

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29
Q

In the evolution of mammals, what are Very late cynodonts

A

In some very late (non-mammalian) cynodonts and early mammals, the original articular-quadrate hinge was lost, leaving the dentary-squamosal hinge as the only hinge between the lower and upper jaws, as in living mammals.

The articular and quadrate bones migrated into the ear region (not shown), where they functioned in transmitting sound. In the mammal lineage, these two bones later evolved into the familiar hammer (malleus) and anvil (incus)

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30
Q

What is the ’temporal fenestra’?

A

An opening in the skull behind the eye socket.

Powerful muscles to close the jaw pass through this “archway”

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31
Q

In the evolution of mammals, where did the hammer (malleus) and anvil (incus) originate?

A

They are derived from the ‘articular-quadrate hinge’

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32
Q

What is the ‘geologic record’?

A

The entirety of the layers of rocks on earth and thus the entirety of Earth’s history

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33
Q

What is the geologic record divided into?

A

Three eons:

These are in order from oldest to most recent: Archaean, Proterozoic and Phanerozoic.

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34
Q

How long did the Archaean eon last?

A

4 billion years

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35
Q

How long did the Proterozoic eon last?

A

4 billion years

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36
Q

How long did the Phanerozoic eon last?

A

Half a billion years

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37
Q

What is the ‘geologic record’?

A

The entirety of the layers of rocks on earth and thus the entirety of Earth’s history

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38
Q

What is the geologic record divided into?

A

Three eons:

These are in order: Archaean, Proterozoic and Phanerozoic.

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39
Q

How long did the Archaean eon last?

A

4 billion years

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40
Q

How long did the Proterozoic eon last?

A

4 billion years

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41
Q

How long did the Phanerozoic eon last?

A

Half a billion years

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42
Q

What is the ‘proterozoic’ eon divided into?

A

The ediacaran period

Other events happened within the proterozoic but outside the Ediacaran

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43
Q

How is the Geologic record divided?

A

It has 3 eons.

An eon is divided into ‘eras’ which are divided into ‘periods’ which are then divided into ‘epochs’

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44
Q

What happened in the Ediacaran period?

A

Diverse algae and soft-bodied invertebrate animals appear

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45
Q

When was the Ediacaran period?

A

542 to 635 mya

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46
Q

What happened in the Archaen eon?

A

In order form first to most recent:

  • Origin of earth
  • Oldest known rocks on earth’s surface
  • Oldest fossils of cells appear
  • Oxygen levels in the atmosphere increase
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47
Q

What is the Phanerozoic eon divided into?

A

The cenozoic, mesozoic and paleozoic eras. (in order from most recent to oldest)

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48
Q

What is the Paleozoic era divided into?

A

The permian, carboniferous, devonian, silurian, ordovician and cambrian periods. (in order from most recent to oldest)

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49
Q

When did the earth first originate?

A

4,600 mya

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50
Q

When dud the first cells (prokaryotes) appear?

A

3,500 mya

51
Q

When dud the first eukaryotes appear?

A

2,100 mya (in the proterozoic era)

52
Q

When was the Permian period?

A

251-299 mya

53
Q

When was the Carboniferous period?

A

299-359 mya

54
Q

When was the Devonian period?

A

359 - 416 mya

55
Q

When was the Silurian period?

A

416 - 444 mya

56
Q

When was the Ordovician period?

A

444 - 488 mya

57
Q

When was the Cambrian period?

A

488 - 542 mya

58
Q

What happened during the Permian period?

A

Radiation of reptiles; origin of most present-day groups of insects; extinction of many marine and terrestrial organisms
at end of period

59
Q

What happened during the Carboniferous period?

A

Extensive forests of vascular

plants form; first seed plants appear; origin of reptiles; amphibians dominant

60
Q

What happened during the Devonian period?

A

Diversification of bony fishes; first tetrapods and insects appear

61
Q

What happened during the Silurian period?

A

Diversification of early vascular plants

62
Q

What happened during the Ordovician period?

A

Marine algae abundant; colonization of land by diverse fungi, plants, and animals

63
Q

What happened during the Cambrian period?

A

Sudden increase in diversity of many animal phyla (Cambrian explosion)

64
Q

What is the mesozoic era of the phanerzoic era divided into?

A

The cretaceous, jurassic and triassic periods. (in order from most recent to oldest)

65
Q

When was the Cretaceous period?

A

65.5 - 145.5 mya

66
Q

When was the Jurassic period?

A

145.5 - 199.6 mya

67
Q

When was the Triassic period?

A

199.6 - 251 mya

68
Q

What happened during the cretaceous period?

A

Flowering plants (angiosperms) appear and diversify; many groups of organisms, including most dinosaurs, become extinct at end of period

69
Q

What happened during the jurassic period?

A

Gymnosperms continue as dominant plants; dinosaurs abundant and diverse.

70
Q

What happened during the triassic period?

A

Cone-bearing plants (gymnosperms) dominate landscape; dinosaurs evolve and radiate; origin of mammals

71
Q

What is the cenozoic era of the phanerozoic eon divided into?

A

The Quaternary, Neogene and Paleogene periods. (in order)

72
Q

What is the Quaternary period divided into?

A

The Holocene and Pleistocene epochs (in order from most recent to oldest)

73
Q

What is the Neogene period divided into?

A

The pliocene and miocene epochs (in order from most recent to oldest)

74
Q

What is the Paleogene period divided into?

A

The oligocene, eocene and paleocene epochs (in order from most recent to oldest)

75
Q

When was the Holocene epoch?

A

Now to 0.01 mya

76
Q

When was the Pleistocene epoch?

A

0.01 - 2.6 mya

77
Q

When was the Pilocene epoch?

A

2.6 - 5.3 mya

78
Q

When was the Miocene epoch?

A

5.3 - 23 mya

79
Q

When was the Oligocene epoch?

A

23 - 33.9 mya

80
Q

When was the Eocene epoch?

A

33.9 - 55.8 mya

81
Q

When was the Palaeocene epoch?

A

55.8 - 65.5 mya

82
Q

What happened during the holocene epoch?

A

It is now to 0.01 mya so modern stuff like the Romans

83
Q

What happened during the pleistocene epoch?

A

Ice ages, the genus Homo began

84
Q

What happened during the pliocene epoch?

A

Appearance of bipedal human ancestors (not in the genus Homo)

85
Q

What happened during the miocene epoch?

A

Continued radiation of mammals and angiosperms; earliest direct human ancestors

86
Q

What happened during the oligocene epoch?

A

Origins of many primate groups

87
Q

What happened during the eocene epoch?

A

Angiosperm dominance increases; continued radiation of most present-day mammalian orders

88
Q

What happened during the paleocene epoch?

A

Major radiation of mammals, birds,

and pollinating insects

89
Q

When was the Cenozoic era?

A

Now to 65.5 mya

90
Q

When was the Paleogene period?

A

23 - 65.5 mya

91
Q

When was the Paleozoic era?

A

251 - 542 mya

92
Q

When was the Proterozoic era?

A

542 - 2500 mya

93
Q

When was the quaternary period?

A

now to 2.6 mya

94
Q

When was the Neogene period?

A

2.6 - 23 mya

95
Q

When was the Paleogene period?

A

23 - 65.5 mya

96
Q

In order what are some of the major events in the history of life on earth?

A

Photosynthesis and the Oxygen Revolution, The First Eukaryotes, Multicellularity, Cambrian Explosion and Colonisation of Land

97
Q

When did oxygen first become widely available?

A

2.7 billion years ago

98
Q

How was the oxygen on earth produced?

A

Largely by cyanobacteria (photosynthetic bacteria)

99
Q

What does the ’Oxygen Revolution’ refer to?

A

The time 2.7 billion years ago when the levels of oxygen in the air skyrocketed.

100
Q

How did the oxygen revolution affect the number of species on earth?

A

Initially it decreased them as the oxygen chemically reduced and thus harmed primitive anaerobic prokaryotes.

However others soon adapted to these conditions and the energetic advantage of being aerobic

101
Q

In what organisms are cytoskeletons found?

A

Only prokaryotes

102
Q

Do prokaryotes have cytoskeltons?

A

No

103
Q

Why is the emergence of cytoskeletons in eukaryotes important?

A

It enables eukaryotic cells to change their shape and thereby surround and engulf other cells.

104
Q

What is some evidence that mitochondria and endosymbiots?

A
  • They replicate in a manner similar to prokaryotes

- They have a single circular chromosome

105
Q

When did the first multicellular eukaryotes appear?

A

About 1.2 billion years ago

106
Q

What is the gradual movement of tectonic plates called?

A

Continental drift

107
Q

What is ‘continental drift’?

A

The gradual movement of the tectonic plates.

This leads to the separation of Pangea

108
Q

How many mass extinction have there been?

A

5 (or six if you include the modern one)

109
Q

What is is called when the groups

of organisms form many new species, each with unique adaptations?

A

Adaptive radiation

110
Q

What is adaptive radiation?

A

Periods of evolutionary change in which groups of organisms form many new species
whose adaptations allow them to fill dif-
ferent ecological roles, or niches, in their
communities.

111
Q

What are some typical situations in which adaptive radiation often occurs?

A
  • After each of the big five mass extinctions, when survivors adapted to the vacant ecological niches.
  • When an organism develops a major evolutionary advantage i.e. seeds
  • Colonised regions with little competition i.e. reaches new island archipelago: one unique species develops per island
112
Q

What are the basic forms of adaptive radiation?

A

‘Worldwide adaptive radiation’ and ‘regional adaptive radiation’

113
Q

What is the fundamental difference between ‘Worldwide adaptive radiation’ and ‘regional adaptive radiation’

A

Worldwide is over a larger scale i.e. new species after a major catastrophe (super-volcano) or an organism with a massive advantage i.e. ability to live on land

Regional is smaller scale. For example a bird reaches a new island archipelago with little competition: becomes many species adapted

114
Q

Alternations in which genes cause the most drastic changes and thus lead to the most profound evolutionary changes?

A

Genes which regulate the timing of development.

Changes in these are called ‘heterochrony’

115
Q

What is heterochrony?

A

When genetic changes lead to a change in the time of developmental stages. This often leads to dramatic changes, such as a vastly different skull shape

116
Q

What are changes to the genes that regulate the timing development called?

A

Heterochrony

117
Q

What is called when sexually mature stage of a species may retain body features that were juvenile structures in an ancestral species?

A

Paedomorphosis

118
Q

What is ‘paedomorphosis’?

A

When a sexually mature stage of a species may retain body features that were juvenile structures in an ancestral species.

For example, most salamander species have aquatic larvae that undergo metamorphosis in becoming adults. But some species grow to adult size and become sexually mature while retaining gills and other larval features

119
Q

What are genes that regulate development called?

A

Homeotic genes

120
Q

What are homeotic genes?

A

Genes that regulate development (not the timing of development - changes to that is called heterchrony)

121
Q

How can complicated structures such as the eye emerge if they don’t appear suddenly but any previous forms would be a massive waste of energy?

A

Actually previous versions of the eyes would not be wasteful: the simple organism with photoreceptor patches found it useful, as did the invertebrates with simple single-lens eyes.

This highlights the idea that natural selection world on the idea of ‘current utility’ in which a complex structure must have also been beneficial to all previous generations/

122
Q

What are the basic ways that ‘current utility’ is achieved?

A
  • A feature, such as the eye, slowly evolves with all previous steps being beneficial to the organism.
  • ‘Exaption’ in which features are utilised for other purposes
123
Q

In terms of evolution, what is it called when features are reused for different purposes?

A

Exaption

124
Q

What is exaption?

A

When features in an organism evolve to perform different roles.

For example the jawbones of the early mammals became the malleus and incus of the ear.

4 Mechanisms of Evolution (4 decks)

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