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Biology 1020 > Origins of Species > Flashcards

Origins of Species Flashcards

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1
Q

Can speciation occur with gene flow

A

NO

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2
Q

is gene flow a homologous or analogous force

A

homologous

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3
Q

speciation

A

divergence of 2 species that results in a macroevolution

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4
Q

what is at the focal point of evolutionary theory

A

speciation

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5
Q

evolutionary theory explains

A

how new species originate and how populations evolve

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6
Q

true or false
the same mechanisms are used for microevolution and macroevolution

A

TRUE

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7
Q

the biological species concept is based on

A

the potential to interbreed rather than on physical similarities

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8
Q

what does the biological species concept emphasis

A

sexual reproduction

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9
Q

what are some limitations of the biological species concept

A
  1. asexual reproduction
  2. extinct species
  3. hybrids (caused by gene flow)
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10
Q

according to the Biological Species concept, what must offspring be to be the same species

A

fertile and viable

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11
Q

what are two issues/challenges with identifying species with the biological species concept

A
  1. species that look SAME but are DIFFERENT (cryptic species)
  2. Species that look DIFFERENT but are the SAME
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12
Q

other species concepts

A
  1. morphological SC
  2. lineage/phylogenetic SC
    3.ecological species concept
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13
Q

morphological SC

A

according to appearance, species that look the same are the same

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14
Q

lineage/phylogenetic SC

A

a shared pattern of ancestry and descent is used to identify species

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15
Q

what is one benefit of the lineage/phylogenetic SC

A

it takes away the limitation of fossil/extinct species

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16
Q

how does speciation express “unity of life”

A

by helping to explain the features that many organisms share

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17
Q

what forms the conceptual bridge between microevolution and macroevolution

A

speciation

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18
Q

what is the primary definition of species

A

biological species concept

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19
Q

according to the BSC, would individuals make viable, fertile offspring with members of another group

A

NO

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20
Q

What holds the gene pool of a species together to cause its members to resemble each other

A

gene flow tends to hold the population together genetically

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21
Q

What can play a role in the formation of new species

A

reduction or lack of gene flow

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22
Q

what does the formation of a new species hinge on

A

reproductive isolation

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23
Q

reproductive isolation

A

Existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring

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24
Q

what is the result of the barriers in reproductive isolation

A
  1. blocking gene flow
  2. limits the formation of hybrids
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25
Q

hybrids

A

Offspring that result from an interspecific mating

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26
Q

how can reproductive barriers be classified

A

according to whether they contribute to reproductive isolation before OR after fertilization

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27
Q

two types of reproductive isolation barriers

A
  1. prezygotic barrier
  2. postzygotic barrier
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28
Q

prezygotic barrier

A

before the zygote

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29
Q

what reproductive barrier is this
blocks fertilization from occurring

A

prezygotic barrier

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30
Q

postzygotic barrier

A

after the zygote

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31
Q

what reproductive barrier is this
contributes to reproductive isolation AFTER the hybrid zygote is formed

A

postzygotic barrier

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32
Q

three ways prezygotic barriers can work

A
  1. Impeding members of different species from attempting to mate
  2. Preventing an attempted mating from being completed successfully
  3. Hindering fertilization if mating is successful
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33
Q

five methods for how prezygotic barriers inhibit fertilization

A
  1. habitat isolation
  2. temporal isolation
  3. behavioral isolation
  4. mechanical isolation
  5. gametic isolation
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34
Q

what reproductive barrier is this
habitat isolation

A

prezygotic

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35
Q

what reproductive barrier is this
temporal isolation

A

prezygotic

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36
Q

what reproductive barrier is this
behavioral isolation

A

prezygotic

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37
Q

what reproductive barrier is this
mechanical isolation

A

prezygotic

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38
Q

what reproductive barrier is this
gametic isolation

A

prezygotic

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39
Q

what reproductive barrier is this
reduced hybrid viability

A

postzygotic

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40
Q

what reproductive barrier is this
reduced hybrid fertility

A

postzygotic

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41
Q

what reproductive barrier is this
hybrid breakdown

A

postzygotic

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42
Q

habitat isolation

A

Two species that occupy the same habitats may encounter each other rarely if at all

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43
Q

true or false
in habitat isolation the species are separated by a PHYSICAL barrier

A

FALSE

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44
Q

temporal isolation

A

species that breed during different times o day, seasons or years cannot mix gametes

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45
Q

behavioural isolation

A

Courtship rituals that are unique to different species

46
Q

what enables mate recognition

A

behavioral isolation barrier

47
Q

mate recognition

A

a way to identify potential mates of the SAME species

48
Q

mechanical isolation

A

mating is attempted but MORPHOLOGICAL differences prevent successful completion

49
Q

gametic isolation

A

sperm of one species is NOT able to fertilize the egg of another species

50
Q

what are 3 postzygotic barriers

A
  1. reduced hybrid fertilization
  2. reduced hybrid viability
  3. hybrid breakdown
51
Q

reduced hybrid fertilization

A

Genes of different parent species interact in ways that impair the hybrid’s development or survival

52
Q

reduced hybrid viability

A

when hybrids are sterile there is NO gene flow between species

53
Q

hybrid breakdown

A

when viable and fertile first generation hybrids mate with another of either parent species the offspring of the next-gen would be STERILE

54
Q

true or false
the morphological SC can be applied to asexual and sexual organisms

A

YES

55
Q

what is a disadvantage of morphological SC

A

relies on subjective criteria

56
Q

ecological species concept

A

views a species in terms of its ecological niche and how its different

57
Q

ecological niche

A

the sum of how members of the species interact with nonliving and living parts of their environment

58
Q

main two ways new species forms

A
  1. allopatric speciation
  2. sympatric speciation
59
Q

allopatric speciation

A

populations are geographically isolated

60
Q

sympatric speciation

A

populations are NOT geographically isolated

61
Q

how is gene flow interrupted in allopatric speciation

A

when a population is divided into geographically isolated subpopulations

62
Q

How formidable must a geographic barrier be to promote allopatric speciation

A

depends on how mobile a species is (smaller rodents would find a wide river more of a barrier than birds)

63
Q

in allopatric speciation, reproductive isolation is a by-product of

A

genetic divergence from selection or drift

64
Q

what is the importance of allopatric speciation

A

Regions that are isolated or highly subdivided by barriers typically have more species than similar regions that lack such features

65
Q

true or false
reproductive isolation decreases as the geographic distance between populations increases in allopatric speciation

A

FALSE, it increases as distance increases

66
Q

what barrier prevents interbreeding when members of different populations meet (after allopatric speciation)

A

BIOLOGICAL

67
Q

sympatric speciation occurs when

A

populations live in the SAME geographic area

68
Q

How can reproductive barriers form between sympatric populations while members remain in contact with each other

A

if gene flow is reduced by factors such as
1. polyploidy
2. sexual selection
3. habitat differentiation

69
Q

true or false
allopatric speciation is LESS common than sympatric speciation

A

FALSE, sympatric speciation is less

70
Q

polyploidy

A

species originating from an accident during cell division that results in extra sets of chromosomes

71
Q

is polyploidy more common in plants or animals

A

plants

72
Q

two types of polyploidy

A
  1. autoploid
  2. allopolypoidy
73
Q

autoploid

A

an individual that has more than two chromosome sets derived from a single species

74
Q

allopolyploid

A

a sterile hybrid changes into a fertile polyploid

75
Q

why are most hybrids sterile?

A

set of chromosomes from one species cannot pair during meiosis with those from the other species

76
Q

why are most hybrids sterile?

A

set of chromosomes from one species cannot pair during meiosis with those from the other species

77
Q

sexual selection

A

females select males based on their appearances

78
Q

habitat differentiation

A

when genetic factors enable a subpopulation to exploit a habitat/resource NOT used by the parent population

79
Q

3 ways sympatric speciation can occur

A
  1. polyploid
  2. sexual selection
  3. habitat differentiation
80
Q

What happens if species with INCOMPLETE reproductive barriers come into contact with one another

A

formation of a hybrid zone

81
Q

hybrid zone

A

Region in which members of different species meet and mate = produce some offspring of mixed ancestry

82
Q

true or false
hybrids are ALWAYS used as a stepping-stone for alleles to be passed from one species to another

A

FALSE, they are rarely used for this

83
Q

hybrid zones are typically located

A

where the habitat of interbreeding species meet

84
Q

Once formed, how does a hybrid zone change over time

A

A change in environment can alter where the habitats of interbreeding species meet = causes existing hybrid zone to move to a new location

85
Q

Three outcomes for the hybrid zone over time if the hybrids DON’T become reproductively isolated

A
  1. reinforcement of barriers
  2. fusion of species
  3. stability
86
Q

Reinforcement is the ________ reproductive barriers

A

strengthing

87
Q

true or false
hybrids are often MORE fit than members of the parent species

A

FALSE

88
Q

Reinforcement

A

natural selection would strength prezygotic barriers to reproduction (reducing formation of unfit hybrids)

89
Q

would reinforcement cause the reproductive barrier between species to be stronger for ______ populations THAN for ________ populations

A

sympatric AND allopatric

90
Q

fusion causes ______ of reproductive barriers

A

weakening

91
Q

why would fusion cause the weakening of reproductive barriers

A

Gene pools for the two species would become increasingly alike if reproductive barriers weakened further with lots of gene flow = fusion into ONE species

92
Q

stability is the ________ formation of hybrids

A

continued

93
Q

if hybrid zones are stable then they

A

continue to produce hyrbids

94
Q

what are two outcomes for a stable hybrid zone

A
  1. hybrids survive better than parent species
  2. hybrids are selected against
95
Q

what two things does evolution by natural selection explain

A
  1. diversity of life
  2. adaptations of organisms
96
Q

Punctuated equilibria

A

describes periods of apparent stasis punctuated by the sudden change

97
Q

punctuated model

A

New species change most as they branch from a parent species and then change LITTLE for the rest of their existence

98
Q

does speciation occur rapidly in the punctuated model

A

YES

99
Q

gradual model

A

Species diverge from one another more slowly and steadily over time

100
Q

TRUE or FALSE
can we tell WHEN a biological species is formed with gradual model

A

NO, info doesn’t fossilize

101
Q

______ periods cannot be distinguished in fossil strata

A

short time periods

102
Q

when can new species arise radiply

A

once divergence begins

103
Q

What is the total length of time between speciation events?

A

time elapsed before populations of a newly formed species start to diverge PLUS time it takes for speciation to be complete once divergence begins

104
Q

Speciation begins only AFTER

A

gene flow between populations is interrupted AND the populations diverge until they become reproductively isolated

105
Q

is this the punctated or gradual model

A

gradual model

106
Q

is this the punctated or gradual model

A

punctuated

107
Q

barriers prevent gene flow in ______ species

A

diverging

108
Q

when can natural selection, genetic drift and mutation act on a separate population

A

AFTER speciation

109
Q

what is the first step towards micro/macroevolution

A

gene flow stops between populations

110
Q

Can speciation occur with gene flow?

A

NO

Biology 1020 (29 decks)

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