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BIOL 1105 > 22: Macroevolution and Speciation > Flashcards

22: Macroevolution and Speciation Flashcards

Module 4, Lesson 5

1
Q

What two phenomena must a species concept account for?

A
  1. Distinctiveness among species that occur in the same location
  2. Connections between populations of the same species living in different areas
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2
Q

Species that live in the same geographic location and often use different parts of the habitat are called…

A

Sympatric

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3
Q

Species that live in different geographic locations, often separated by a physical barrier, are called…

A

Allopatric

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4
Q

When two different species inhabit the same area but remain distinct, they are…

A

Sympatric

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5
Q

Sympatric species usually have visible…

A

Morphological differences

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6
Q

True or false:

Sometimes sympatric species will have differences that are less visible.

A

True

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7
Q

Populations tend to exhibit geographic…

A

Variation

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8
Q

True or false:

A species is normally found in a continuous range.

A

False

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9
Q

When populations of the same species are located in different areas, they often…

A

Have distinct differences

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10
Q

Distinctly different populations of the same species may be classified as…

A

Subspecies

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11
Q

In order to be considered the same species, members of different subspecies must be able to…

A

Produce fertile offspring together

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12
Q

Why do sympatric species remain distinct despite living in the same location?

A

They only exchange genetic material with members of the same species

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13
Q

In order to remain the same species, geographically distant populations must…

A

Experience some gene flow

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14
Q

____ occurs when individuals cannot/will not mate with each other, or when they cannot produce fertile offspring.

A

Reproductive isolation

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15
Q

Reproductive isolation is a critical aspect of…

A

Speciation

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16
Q

In order for reproductive isolation to occur, ____ must happen.

A

A disruption in gene flow

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17
Q

List the two main mechanisms of reproductive isolation.

A
  1. Pre-zygotic
  2. Post-zygotic
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18
Q

Pre-zygotic isolation mechanisms are those that…

A

Prevent a zygote from forming

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19
Q

List the five main mechanisms of pre-zygotic isolation.

A
  1. Ecological isolation
  2. Behavioral isolation
  3. Temporal isolation
  4. Mechanical isolation
  5. Prevention of gamete fusion
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20
Q

Post-zygotic isolation mechanisms are those that…

A

Impact hybrid zygotes

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21
Q

List the three main mechanisms of post-zygotic isolation.

A
  1. Hybrid inviability
  2. Hybrid infertility
  3. Hybrid breakdown
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22
Q

____ occurs when species that live in the same area use different areas of the environment, causing them to not interact.

A

Ecological isolation

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23
Q

The fact that lions and tigers can produce hybrid offspring but rarely do so is due to…

A

Ecological isolation

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24
Q

____ occurs when differences in courtship/mating rituals prevent different species from accidentally mating.

A

Behavioral isolation

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25
Q

____ occurs when species do not mate because they have different mating/breeding seasons.

A

Temporal isolation

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26
Q

True or false:

Species that are temporally isolated may be able to hybridize in a lab.

A

True

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27
Q

____ occurs when structural differences in reproductive systems prevent mating.

A

Mechanical isolation

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28
Q

The fact that many flowers have unique structures or pollinators that limit pollen transfer between species is an example of…

A

Mechanical isolation

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29
Q

____ is an important mechanism for plants and animals that shed gametes directly into water.

A

Prevention of gamete fusion

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30
Q

True or false:

Only species that use external fertilization can use mechanisms that prevent gamete fusion.

A

False

Some species that use internal fertilization also have mechanisms that prevent sperm/pollen from fertilizing eggs.

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31
Q

If mating does occur between members of different species, ____ may prevent hybrids from being produced.

A

Post-zygotic isolating mechanisms

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32
Q

____ occurs when hybrid embryos do not develop properly, causing them to die before or shortly after birth.

A

Hybrid inviability

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33
Q

____ causes many surviving hybrids to be sterile.

A

Hybrid infertility

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34
Q

____ occurs when hybrids survive and are fertile, but have much lower fitness than their parents.

A

Hybrid breakdown

35
Q

Under the ____, individuals have to be able to produce fertile offspring to be considered members of the same species.

A

Biological species concept

36
Q

The biological species concept defined “species” as…

A

A group of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.

37
Q

List five major complications to the biological species concept.

A
  1. Sometimes individuals classified as separate species will produce fertile intermediate offspring
  2. In-depth studies are often required
  3. Hybridization is common between plant species
  4. It is difficult to apply to geographically isolated populations
  5. It does not apply to asexual organisms
38
Q

Why does the biological species concept often require in-depth studies of closely-related species?

A

To investigate whether they are interbreeding and producing fertile offspring

39
Q

It is difficult to classify plants using the biological species concept because…

A

Hybridization is very common among plants

40
Q

It is difficult to apply the biological species concept to geographically isolated populations because…

A

Interbreeding cannot be observed

41
Q

Why does the biological species concept not apply to asexual organisms?

A

They do not mate

42
Q

The utility of the biological species concept is limited to…

A

Organisms that reproduce sexually

43
Q

The ____ applies the term “species” only to populations that have been evolving independently of other populations.

A

Phylogenetic species concept

44
Q

Under the phylogenetic species concept, species are identified using…

A

Phylogenetic analysis

45
Q

____ represent hypotheses of relationships between species based on analysis of shared traits.

A

Phylogenies

46
Q

Phylogenies are also called…

A

“Evolutionary trees”

47
Q

What two complications of the biological species concept are solved by the phylogenetic species concept?

A
  1. Does not require knowledge about the ability of allopatric populations to interbreed
  2. Can be applied to both sexually- and asexually-reproducing species
48
Q

List two drawbacks to the phylogenetic species concept.

A
  1. It can lead to defining every slightly different population as a new species
  2. Populations in a species may not be descended from a single ancestor
49
Q

True or false:

It is relatively simple to define a species, and there is little debate in the scientific community about the criteria used.

A

False

50
Q

Isolating mechanisms may be reinforced by…

A

Selection

51
Q

Species formation is a ____ process.

A

Continuous

52
Q

True or false:

During the process of species formation, two populations may be only partially reproductively isolated.

A

True

53
Q

What happens if two different populations are not fully reproductively isolated and begin interbreeding?

A

Over time, their differences will disappear and speciation will not occur

54
Q

What happens if two populations are already reproductively isolated by the time they meet?

A

They will remain separate species

55
Q

If hybrids are partially sterile, then selection will prioritize alleles that…

A

Prevent hybridization

56
Q

True or false:

It can be argued that “selection may favor reproductive isolation”

A

True

57
Q

The continual improvement of pre-zygotic isolation mechanisms is called…

A

Reinforcement

58
Q

When two populations are ____, they may display similar morphological features.

A

Geographically isolated

59
Q

When two populations occur ____, they will often evolve less similar morphology.

A

Sympatrically

60
Q

The development of different morphologies is a ____ isolation mechanism.

A

Pre-zygotic

61
Q

When two species live sympatrically, pre-zygotic isolation mechanisms will…

A

Continually improve

62
Q

____ can counter speciation.

A

Gene flow

63
Q

True or false:

Reinforcement always results in speciation.

A

False

64
Q

When partially isolated populations meet, some degree of gene flow will occur if…

A

Any of the hybrids are fertile

65
Q

____ serve as a conduit for gene flow.

A

Surviving hybrids

66
Q

Adaptive changes in mating signals can result from ____ in new environments.

A

Selective forces

67
Q

Adaptive changes can eventually result in….

A

Reproductive isolation

68
Q

Random changes in allele frequence can cause…

A

Reproductive isolation

69
Q

With enough time, any isolated population will diverge due to…

A

Genetic drift

70
Q

If divergence leads to traits which cause reproductive isolation, ____ occurs.

A

Speciation

71
Q

If geographic changes cause a population to be broken into smaller populations, then…

A

Gene flow stops and allopatric speciation may occur

72
Q

When two similar populations evolve into separate species over time due to geographic isolation, ____ occurs.

A

Allopatric speciation

73
Q

Sometimes, geographic isolation is an important prerequisite for…

A

Speciation

74
Q

Mainland populations of a species show little variation because…

A

Gene flow is constantly occuring

75
Q

Isolated island populations show a lot of variation, because…

A

Gene flow is very limited

76
Q

____ refers to a group of species that recently evolved from a common ancestor by adapting to different parts of the environment.

A

Adaptive radiation

77
Q

Adaptive radiation can lead to…

A

Diversity

78
Q

The rapid diversification of cichlid populations in Lake Victoria is an example of…

A

Adaptive radiation

79
Q

List the two hypothesis that attempt to explain the relationship between speciation and the evolutionary changes that occur within a species over time.

A
  1. Gradualism
  2. Punctuated equilibrium
80
Q

True or false:

Gradualism and punctuated equilibrium are mutually exclusive.

A

False

81
Q

True or false:

A species may have experienced episodes of both gradualism and punctuated equilibrium over its history.

A

True

82
Q

The hypothesis that small changes occur very slowly, accumulating into large changes over thousands and millions of years, is called…

A

Gradualism

83
Q

The hypothesis that species experience periods of little to no change interspersed with short bursts of rapid evolution is called…

A

Punctuated equilibrium

BIOL 1105 (26 decks)

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