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IB Biology > 5.1 Evidence for Evolution > Flashcards

5.1 Evidence for Evolution Flashcards

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1
Q

What is evolution in its most simplest form?

A

Evolution at its most fundamental level simply describes a change over time

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2
Q

What does biological evolution in organisms refer to?

A

In living organisms this change refers to the heritable characteristics of a species (biological evolution)

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3
Q

How are heritable characteristics encoded and transferred?

A

Heritable characteristics are encoded for by genes and may be transferred between generations as alleles

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4
Q

What does biological evolution due to gene transferal between generations describe

A

Hence biological evolution describes cumulative changes that occur within a population between one generation and the next

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5
Q

What is a concise definition of biological evolution?

A

A change in the allele frequency of a population’s gene pool over successive generations

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6
Q

What characteristic does something need to have to show evidence for evolution?

A

Something provides evidence for evolution when it demonstrates a change in characteristics from an ancestral form

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7
Q

What evidence does the fossil record provide?

A

The fossil record provides evidence by revealing the features of an ancestor for comparison against living descendants

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8
Q

What is a fossil?

A

A fossil is the preserved remains or traces of any organism from the remote past

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9
Q

What evidence do preserved remains provide?

A

Preserved remains (body fossils) provide direct evidence of ancestral forms and include bones, teeth, shells, leaves, etc.

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10
Q

What evidence do traces provide?

A

Traces provide indirect evidence of ancestral forms and include footprints, tooth marks, burrows and faeces (coprolite)

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11
Q

What is the fossil record?

A

The totality of fossils, both discovered and undiscovered, is referred to as the fossil record

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12
Q

What does the fossil record show?

A

The fossil record shows that over time changes have occurred in the features of living organisms (evolution)

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13
Q

How can fossils be dated?

A

Fossils can be dated by determining the age of the rock layer (strata) in which the fossil is found

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14
Q

In what order does sedimentary rock develop?

A

Sedimentary rock layers develop in a chronological order, such that lower layers are older and newer strata form on top

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15
Q

What does each strata in sedimentary rock represent?

A

Each strata represents a variable length of time that is classified according to a geological time scale (eons, eras, periods)

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16
Q

How does sedimentary rock indicate a sequence of develop?

A

Different kinds of organisms are found in rocks of particular ages in a consistent order, indicating a sequence of development

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17
Q

Do eu/prokaryotes appear first in sedimentary rock?

A

Prokaryotes appear in the fossil record before eukaryotes

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18
Q

Do ferns or flowering plants appear first in sedimentary rock?

A

Ferns appear in the fossil record before flowering plants

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19
Q

Do in/vertebrate species appear first in sedimentary rock?

A

Invertebrates appear in the fossil record before vertebrate species

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20
Q

What is the law of fossil succession?

A

This chronological sequence of complexity by which characteristics appear to develop is known as the law of fossil succession

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21
Q

What does the law of fossil succession suggest?

A

This ordered succession of fossils suggests that newer species likely evolved as a result of changes to ancestral species

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22
Q

Is the fossil record complete?

A

NO
While fossils may provide clues as to evolutionary relationships, it is important to realise that the fossil record is incomplete

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23
Q

Why are there few fossils?

A

Fossilisation requires an unusual set of specific circumstances in order to occur, meaning very few organisms become fossils

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24
Q

Why are only fragments of an organism fossilised?

A

Only the hard parts of an organism are typically preserved, meaning usually only fragments of remains are discovered

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25
Q

What problem arises from an incomplete fossil record?

A

With limited fossil data, it can be difficult to discern the evolutionary patterns that result from ancestral forms (‘missing links’)

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26
Q

What do transitional fossils demonstrate?

A

Transitional fossils demonstrate the intermediary forms that occurred over the evolutionary pathway taken by a single genus

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27
Q

What link do transitional fossils establish?

A

They establish the links between species by exhibiting traits common to both an ancestor and its predicted descendents

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28
Q

What is an example of a transitional fossil? What does it link?

A

An example of a transitional fossil is archaeopteryx, which links the evolution of dinosaurs (jaws, claws) to birds (feathers)

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29
Q

What happens as new fossils are discovered?

A

As new fossils are discovered, new evolutionary patterns are emerging and old assumptions are challenged

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30
Q

What can be compared to give an example of how fossils can act as evidence?

A

An example of how fossils provide evidence of evolution can be established by comparing hominin skeleton

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31
Q

What is the earliest hominin ancestor?

A

Australopithecus is an early hominin ancestor that first appears in the fossil record approximately 4 million years ago

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32
Q

What can Australopithecus be compared to?

A

Comparing these fossils to the bone structure of modern man (Homo sapiens) demonstrates key evolutionary changes

33
Q

Give 5 examples of structural changes from Australopithecus to homo sapiens and their evolutionary advantages

A
  1. larger cranial capacity - increased intellectual prowess
  2. smaller teeth and narrower jaw - changed dietary requirements (more meat)
  3. lower and broader pelvis - altered birthing patterns (larger infants)
  4. marked reduction in body hair - reflects use of fur clothing from hunting
  5. increased average height - consequence of improved diet
34
Q

What is selective breeding a form of?

A

Selective breeding is a form of artificial selection, whereby man intervenes in the breeding of species to produce desired traits in offspring

35
Q

What increases in frequency via selective breeding?

A

By breeding members of a species with a desired trait, the trait’s frequency becomes more common in successive generations

36
Q

How does selective breeding provide evidence for evolution?

A

Selective breeding provides evidence of evolution as targeted breeds can show significant variation in a (relatively) short period

37
Q

What has selective breeding of plant crops allowed for?

A

Selective breeding of plant crops has allowed for the generation of new types of foods from the same ancestral plant source

38
Q

How have plants of the genus Brassica been bred?

A

Plants of the genus Brassica have been bred to produce different foods by modifying plant sections through artificial selection

39
Q

What are examples of selectively bred plants from the genus Brassica?

A

This includes broccoli (modified flower buds), cabbage (modified leaf buds) and kale (modified leaves)

40
Q

What has the selective breeding of domesticated animals resulted in and give an example?

A

Selective breeding of domesticated animals has also resulted in the generation of diverse breeds of offspring

Examples of selective breeding of domesticated animals can be seen in horse, cows and dogs

41
Q

Why have horses been selectively bred? (general)

A

Horses have been selectively bred across many generations to produce variation according to a targeted function

42
Q

What have race horses been selectively bred for?

A

Race horses have been bred for speed and hence are typically leaner, lighter, taller and quicker

43
Q

What have draft horses been selectively bred for?

A

Draft horses have been bred for power and endurance and hence are sturdier and stockier

44
Q

What are the two reasons cows gave been selectively bred?

A

Cows have been selectively bred across many generations to produce offspring with improved milk production

Farmers have also targeted the breeding a cows with a mutation resulting in increased muscle mass

45
Q

What is the result of the selective breeding of cows? (organism name)

A

The resulting stock of cattle (termed Belgian Blue) have excessive bulk and produce more edible lean meat

46
Q

What have hunting dogs been selectively bred for?

A

Hunting dogs (e.g. beagles) were typically bred to be smaller in stature so as to enter fox holes

47
Q

What have herding dogs been selectively bred for?

A

Herding dogs (e.g. sheep dogs) were bred for heightened intelligence in order to follow herding commands

48
Q

What have racing dogs been selectively bred for?

A

Racing dogs (e.g. greyhounds) were specifically bred to be sleek and fast

49
Q

What have toy dogs been selectively bred for?

A

Toy dogs (e.g. chihuahuas) were selectively bred for their diminutive size

50
Q

What may comparative anatomy show?

A

Comparative anatomy of groups of organisms may show certain structural features that are similar, implying common ancestry

51
Q

What are homologous structures?

A

Anatomical features that are similar in basic structure despite being used in different ways are called homologous structures

52
Q

What does it mean if the homologous structures of two species are similar?

A

The more similar the homologous structures between two species are, the more closely related they are likely to be

53
Q

What do homologous structures indicate? Give a definition

A

Homologous structures illustrate adaptive radiation, whereby several new species rapidly diversify from an ancestral source, with each new species adapted to utilise a specific unoccupied niche

54
Q

What is an example of homologous structures?

A

A classical example of homologous structures is the pentadactyl limb in a variety of different animals

55
Q

What organisms share the pentadactyl limb?

A

Mammals, birds, amphibians and reptiles all share a similar arrangement of bones in their appendages based on a five-digit limb

56
Q

How may animal limbs differ?

A

Despite possessing similar bone arrangements, animal limbs may be highly dissimilar according to the mode of locomotion:

57
Q

What are human hands adapted for?

A

Human hands are adapted for tool manipulation (power vs precision grip)

58
Q

What are bird and bat wings adapted for?

A

Bird and bat wings are adapted for flying

59
Q

What are horse hooves adapted for?

A

Horse hooves are adapted for galloping

60
Q

What are whale and dolphin fins adapted for?

A

Whale and dolphin fins are adapted for swimming

61
Q

What variation will be present in a population of a species?

A

Within a population of any given species there will be genetic variation (i.e. variation which is inheritable)

62
Q

What will genetic variation follow? (dis/continous + distribution)

A

Typically this variation will be continuous and follow a normal distribution curve as the rate of change is gradual and cumulative

63
Q

What will happen if two populations of a species become geographically separated?

A

If two populations of a species become geographically separated then they will likely experience different ecological conditions

Over time, the two populations will adapt to the different environmental conditions and gradually diverge from one another

64
Q

What will the degree of divergence of the two species depend on?

A

The degree of divergence will depend on the extent of geographical separation and the amount of time since separation occurred

65
Q

What populations show less divergence?

A

Populations located in close proximity that separated recently will show less variation (less divergence)

66
Q

What populations show more divergence?

A

Distant populations that separated a longer period of time ago will show more variation (more divergence)

67
Q

What will the degree of divergence increase alongside?

A

The degree of divergence between geographically separated populations will gradually increase the longer they are separated

68
Q

What decreases alongside an increase in divergence?

A

As the genetic divergence between the related populations increase, their genetic compatibility consequently decreases

69
Q

To what extent can species diverge?

A

Eventually, the two populations will diverge to an extent where they can no longer interbreed if returned to a shared environment

70
Q

hen are two species considered to be separate?

A

When two populations can no longer interbreed and produce fertile, viable offspring they are considered to be separate species

71
Q

What is speciation?

A

The evolutionary process by which two related populations diverge into separate species is called speciation

72
Q

In what two forms do peppered moths exist?

A

Peppered moths (Biston betularia) exist in two distinct polymorphic forms – a light colouration and a darker melanic variant

73
Q

What type of moth is predominant with low pollution?

A

In an unpolluted environment, the trees are covered by a pale-coloured lichen, which provides camouflage for the lighter moth

74
Q

What type of moth is predominant with high pollution?

A

In a polluted environment, sulphur dioxide kills the lichen while soot blackens the bark, providing camouflage for the dark moth

75
Q

What is the frequency of the two different forms of the moth dependent upon?

A

The frequency of the two different forms of peppered moth is dependent on the environment and evolves as conditions change

76
Q

What moth was predominant before the industrial evolution?

A

Before the industrial revolution, the environment was largely unpolluted and the lighter moth had a survival advantage

77
Q

What moth was predominant after the industrial evolution?

A

Following the industrial revolution, the environment became heavily polluted, conferring a survival advantage to the darker moth

78
Q

What is causing the frequency of the variations of the peppered moth to differ in modern days?

A

Recent environmental policies in Europe are reducing pollution levels, altering the frequency of the two populations once again

IB Biology (38 decks)

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