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Systematics > Origin of Species > Flashcards

Origin of Species Flashcards

1
Q

the origin of new species is at the focal point of Darwin’s evolutionary theory.

A

speciation

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2
Q

must explain how new species originate and how populations evolve.

A

evolutionary theory

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3
Q

consists of adaptations that evolve within a population, confined to one gene pool.

A

Microevolution

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4
Q

refers to evolutionary change above the species level.

A

macroevolution

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5
Q

The Biological Species Concept emphasizes __

A

reproductive isolation

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6
Q

Biologists compare __, __, __, and __ when grouping organisms.

A

morphology, physiology, biochemistry, and DNA sequences

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7
Q

species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations.

A

biological species concept

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8
Q

Reproductive Isolation =

A

Barriers to Interbreeding

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9
Q

is the existence of biological factors (barriers) that impede two different species from producing viable, fertile offspring.

A

Reproductive isolation

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10
Q

are the offspring of crosses between different species.

A

Hybrids

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11
Q

Reproductive isolation can be classified by whether factors act ___ or ___ fertilization.

A

before (prezygotic); after (postzygotic)

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12
Q

Prezygotic barriers block fertilization from occurring
by:

A

– Impeding different species from attempting to mate.
– Preventing the successful completion of mating.
– Hindering fertilization if mating is successful.

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13
Q

Prezygotic barriers maintain reproductive isolation and
include:

A

Temporal, Habitat, Behavioral, Mechanical, and
Gamete Isolation

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14
Q

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.

A

Habitat isolation (e.g. Water-dwelling Thamnophis and Terrestrial Thamnophis)

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14
Q

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.

A

Habitat isolation (e.g. Water-dwelling Thamnophis and Terrestrial Thamnophis)

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15
Q

What are the PreZygotic Reproductive Barriers

A
  • Temporal Isolation
  • Behavioral isolation
  • Mechanical isolation
  • Gametic isolation
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16
Q

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes.

A

Temporal isolation

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17
Q

Courtship rituals and other behaviors unique to a species are effective barriers.

A

Behavioral isolation (e.g. Courtship ritual of blue-footed boobies)

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18
Q

Morphological differences can prevent successful mating.

A

Mechanical Isolation (e.g. Bradybaena with shells spiraling in opposite directions)

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19
Q

The sperm of one species may not be able to fertilize the eggs of another species.

A

Gametic isolation

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20
Q

prevent the hybrid zygote from developing into a viable, fertile adult

A

Postzygotic barriers

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21
Q

Species is a Latin word meaning

A

“kind” or “appearance”

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22
Q

Between populations, it holds the phenotype of a population together

A

Gene flow

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23
Q

Genes of the different parent species may interact and impair the hybrid’s development

A

Reduced hybrid viability

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24
Q

Even if hybrids are vigorous, they may be sterile

A

Reduced hybrid fertility (e.g. Mule: sterile hybrid offspring between horse and donkey)

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25
Q

Some of the first-generation hybrids are fertile, but when they mate with another species or with either parent species, the offspring of the next generation are feeble or sterile

A

hybrid breakdown

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26
Q

the change in frequency of an existing gene variant in the population due to random chance.

A

genetic drift

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26
Q

Some of the first-generation hybrids are fertile, but when they mate with another species or with either parent species, the offspring of the next generation are feeble or sterile

A

hybrid breakdown

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27
Q

The biological species concept cannot be applied to ___.

A
  • fossils
  • asexual organisms (including all prokaryotes)
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28
Q

Other species concepts emphasize the ___ within a species rather than the __ of different species.

A

unity; separateness

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29
Q

defines a species by structural features.

A

morphological species concept

30
Q

It applies to sexual and asexual species but relies
on subjective criteria.

A

morphological species concept

31
Q

emphasizes the absence of gene flow

A

biological species concept

32
Q

views a species in terms of its ecological niche.

A

ecological species concept

33
Q

In ecological species concept, it applies to sexual and asexual species and emphasizes the role of ____.

A

disruptive selection

34
Q

when more extreme phenotypes (or genotypes) within a population have a fitness advantage over intermediate individuals.

A

disruptive selection

35
Q

defines a species as the smallest group of individuals on a phylogenetic tree.

A

phylogenetic species concept

36
Q

Phylogenetic species concept applies to sexual and asexual species, but it can be difficult to determine the ____ required for separate species.

A

degree of difference

37
Q

Speciation can occur in two ways

A
  • Allopatric speciation: geographic barrier separates populations.
    – Sympatric speciation: no geographic barrier
38
Q

A population forms a new species while geographically isolated from its parent population

A

allopatric speciation

39
Q

a subset of the population forms a new species without geographic separation

A

Sympatric speciation

40
Q

In allopatric speciation, ___ is interrupted, or ___ is the cumulative effect of many speciation and extinction events.

A

gene flow; macroevolution

41
Q

separates the original population.

A

geographic barrier

42
Q

Separate populations may evolve independently
through

A
  • mutation
  • natural selection
  • genetic drift.
43
Q

generally increases as the distance between populations increases.

A

Reproductive isolation

44
Q

Allopatric speciation is also called

A

“Other Country” Speciation

45
Q

Barriers to reproduction are ___; separation itself is not a biological barrier.

A

intrinsic

46
Q

may arise as a result of genetic divergence

A

reproductive isolation

47
Q

speciation takes place in geographically overlapping populations.

A

sympatric speciation

48
Q

the presence of extra sets of chromosomes due to accidents during cell division.

A

polyploidy (common in plants)

49
Q

is an individual with more than two chromosome sets, derived from one species.

A

autopolyploid

50
Q

a species with multiple sets of chromosomes derived from different species.

A

allopolyploid

51
Q

a species with multiple sets of chromosomes derived from different species.

A

allopolyploid

52
Q

sources of sympatric speciation

A
  • polyploidy
  • habitat differentiation*
  • natural selection
  • sexual selection
53
Q

can also result from the appearance of new ecological niches.

A

sympatric speciation

54
Q

can drive sympatric speciation.

A

sexual selection

55
Q

In allopatric speciation, geographic separation
restricts __ between populations.

A

gene flow

56
Q

In sympatric speciation, a ____ isolates a subset of a population without geographic separation from the parent species.

A

reproductive barrier

57
Q

A hybrid zone can occur in a single band where
____.

A

adjacent species meet

58
Q

Hybrids often have ___ compared with parent species.

A

reduced fitness

59
Q

the result of mating between species with incomplete reproductive barriers

A

hybrids

60
Q

When closely related species meet in a hybrid
zone, there are three possible outcomes:

A
  • Reinforcement
  • Fusion
  • Stability
60
Q

Strengthening of reproductive barriers reducing gene flow.

A

reinforcement

61
Q

Weakening of reproductive barriers with eventual fusion into one species.

A

fusion

62
Q

Continued formation of hybrid individuals.

A

Stabilizing

62
Q
  • occurs when hybrids are less fit than the parent species
  • over time, the rate of hybridization decreases
  • reproductive barriers should be stronger for sympatric than allopatric species
A

reinforcement of gene flow barrier

63
Q
  • if hybrids are as fit as parents, there can be substantial gene flow between species
  • if the gene flow is great enough, the parent species can fuse into a single species
A

Fusion: Weakening Reproductive Barriers

64
Q

extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone

A

Stability: Continued Formation of Hybrid Individuals

65
Q

Broad patterns in speciation can be studied using the

A
  • fossil record
  • morphological data
  • molecular data
66
Q

describe periods of apparent stasis (no change) punctuated by brief periods of rapid change.

A

punctuated equilibrium

67
Q

coined the term punctuated equilibrium

A

Niles Eldredge and Stephen Jay Gould

68
Q

The punctuated equilibrium model contrasts with a

A

Darwinian model of gradualism

69
Q

slow continuous change over time in a species’ existence.

A

Darwinian model of gradualism:

70
Q

enabling researchers to identify specific genes involved in some cases of speciation.

A

explosion of genomics

71
Q

Depending on the species in question,
speciation might require the change of only __

A

a single allele or many alleles.

72
Q

the cumulative effect of many speciation and extinction events.

A

macroevolution

73
Q

the cumulative effect of many speciation and extinction events.

A

macroevolution

Systematics (15 decks)

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