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Biology 106; Exam #2 > Exam #2, Speciation > Flashcards

Exam #2, Speciation Flashcards

1
Q

Define Species

A

Species are groups of organisms that share genetic and morphological attributes

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2
Q

Define Reproductive Isolation

A

a state in which two groups can no longer exchange genes

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3
Q

True or False: are Species Reproductive Isolated from other groups?

A

True

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4
Q

What is the base unit of taxonomic classification?

A

Species is the base unit of taxonomic classification.

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5
Q

Define Speciation

A

the process of splitting one population into two populations that are reproductively isolated from one another

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6
Q

Species are a result of ___

A

speciation

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7
Q

why do biologists think about species differently

A

Biologists think about species differently because they ask different questions, which are known as species concepts

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8
Q

Define Morphological species concept

A

Is a construct that assumes that a species comprises individuals that “look-alike” and that those that do not look alike belong to different species

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9
Q

Who developed the concept of Morphological Species and the system of binomial nomenclature

A

Carl Linnaeus

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10
Q

In the Morphological species concept, there are Limitations. Define what the term Limitations mean.

A

Members of the same species do not always look alike

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11
Q

In limitations that can be Cryptic Species. Define cryptic Species.

A

Cryptic species are instances in which two or more species are morphologically indistinguishable but do not interbreed. For example, Hyla versicolor and the Hylya Chrysoscelis.

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12
Q

Define: Biological Species Concept

A

Definition of a species as a group of “actually” or “potentially” interbreeding natural populations that are reproductively isolated from other such groups.

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13
Q

Explain what the term “actually” means in the definition of the biological species concept

A

“actually” implies that the individuals live in the same area and interbreed with one another

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14
Q

Explain what the term “potentially” means in the definition of the biological species concept

A

“Potentially” implies that the individuals do not live in the same area, therefore, do not interbreed, but other information suggests that they would if they were together

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15
Q

Does the biological species concept apply to asexually reproducing organisms?

A

No

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16
Q

Define: Lineage Species Concept

A

Definition of a species as a branch on the tree of life, which has a history that starts at a speciation event and ends either at extinction or at another speciation event

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17
Q

Define: lineage

A

A lineage is a series of populations, species, or genes descended from a single ancestor over evolutionary time

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18
Q

Is lineage splitting a gradual or quick process?

A

Lineage splitting is a gradual process that can take up to thousands of generations to complete.

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19
Q

True or False: speciation does not require the interruption of gene flow within a species whose members formerly exchanged genes

A

False, speciation does require the interruption of gene flow within a species whose members formerly exchanged genes.

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20
Q

What is the cause of reproductive isolation in speciation?

A

Incompatibilities between genes

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21
Q

Name the model that describes how reproductive isolation between two physical isolated populations can develop through the accumulation of incompatible genes or chromosomal arrangements

A

Dobzhansky-Muller Model

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22
Q

Explain two events that might occur through the Dobzhansky-Muller Model

A
  1. some combinations of these differentiated genes or chromosomes will not function well together in hybrids
  2. genetic incompatibility will develop over time
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23
Q

note 1

A
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24
Q

note 2

A
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25
Q

note 3

A
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26
Q

Splitting of the ______ ______ of a species is one way of achieving reproductive isolation

A

geographic range

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27
Q

When does Allopatric Speciation occur?

A

Allopatric speciation occurs when a physical barrier separates populations

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28
Q

What is the dominant mode of speciation in most groups?

A

Allopatric Speciation

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29
Q

We know that in Allopatric Speciation, populations are separated by a physical barrier. Explain how they are physically divided.

A

A barrier that divides may be a body of water or a mountain range for terrestrial organisms or dry land for aquatic organisms. Moreover, these can form as continents drift, sea level changes, glacier advance and retreat, and climate change.

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30
Q

True or False: In Allopatric speciation, the environments in which the isolated populations live are different and, so the populations evolve differently.

A

True

31
Q

_____ ______ can occur if some individuals cross a barrier to form a new, isolated population

A

Allopatric Speciation

32
Q

The __ species of finches on the Galapagos (___ ___) arose from a ___ species that colonized the islands from ___ ____

A

14; Darwins Finches; single; South America

33
Q

Explain why Allopatric Speciation occurred with Darwins finches

A

The islands have different environments, and are sufficiently far apart for speciation to occur

34
Q

The effectiveness of physical barriers depends on….

A

the size and mobility of the organisms

35
Q

Does Sympatric Speciation occur with or without physical barriers

A

without

36
Q

list the two common forms of sympatric speciation

A
  1. Disruptive Selection
    2.) Polyploidy
37
Q

Define Disruptive Selection

A

Disruptive Selection is when individuals with certain genotypes have a preference for distinct microhabitats where mating takes place

38
Q

Define: Polyploidy

A

the duplication of sets of chromosomes within individuals

39
Q

Polyploidy can arise from two factors. List them.

A

1.) autopolyploidy
2.) allopolyploidy

40
Q

Define Autopolyploidy

A

Autopolyploidy occurs from chromosome duplication in a single species

41
Q

Define Allopolyploidy

A

Allopolyploidy is the combining of the chromosomes of two different species

42
Q

Polyploidy can result in complete reproductive isolation in ___ generations

A

two

43
Q

What process is an exception to the general rule that speciation is a gradual process

A

Polyploidy

44
Q

______ is likely to occur when reproductive isolation is incomplete, and these species come back into contact

A

Hybridization

45
Q

Mechanisms of reproductive incompatibility fall into two categories. Name them.

A

1.) Prezygotic (before fertilization) isolating mechanisms 2.) Postzygotic isolating mechanisms

46
Q

Define Prezygotic Isolating Mechanisms and the 5 types of isolation mechanisms that can occur

A

prevent hybridization from occurring
1.) mechanical
2.) Temporal
3.) Behavioral
4.) Habitat
5.) gametic

47
Q

Define: Postzygotic Isolating Mechanisms and the 3 types of isolating mechanisms that can occur

A

Reduce the fitness of hybrid offspring.

1.) Low hybrid zygote viability
2.) Loy hybrid adult viability
3.) Hybrid infertility

48
Q

Define: Mechanical Isolation

A

Differences in the size and shape of reproductive organs may prevent the union of gametes from different species.

49
Q

True or False: Reproduction between individuals with mismatched reproductive structures is not
physically possible

A

True

50
Q

Give an example of a Mechanical Isolation

A

two different species of snails’ shells may spiral in opposites directions,
thus the genital openings due not align and no mating can occur

51
Q

Define: Temporal Isolation

A

When mating periods do not overlap

52
Q

When does temporal isolation occur

A

Many organism have distinct mating
seasons and if two closely related
species breed at different times of the
year (or different times of day), they may
never have an opportunity to hybridize

53
Q

Give an example of temporal isolation

A

breeding seasons of three
species of leopard frogs overlap when
they are physically separated but do not
overlap when they live together

54
Q

Define: Behavioral Isolation

A

individuals may reject, or tail to recognize, individuals of other species as potential mates

55
Q

Given an example of behavioral isolation

A
  • mating calls of male frogs of related
    species diverge quickly
  • Mate choice of one species may be mediated by
    the behavior of other species
    1. Example: pollinators determine pollination
56
Q

Define: Habitat Isolation

A

when two closely related species evolve preferences
for living or mating in different habitats
- May never physically come into contact

57
Q

Define: Gametic Isolation

A

eggs of one species do not have appropriate
chemical signals for sperm of another species; or sperm is not able to
attach to and penetrate the egg
- No zygote formation

58
Q

True or False:Genetic differences that accumulate between two diverging lineages
may reduce the survival and reproductive rates of hybrid offspring

A

True

59
Q

Define Low Hybrid zygote viability

A

failure of zygotes to mature or develop severe
abnormalities

60
Q

Define: Low hybrid adult viability

A

hybrid offspring may have lower survival rates

61
Q

Define: Hybrid Infertility

A

hybrids may mature into infertile adults
1. Example: mules produce no descendants

62
Q

Speciation rates are ___ variable across life

A

highly

63
Q

Speciation rates are influenced by _____ and _______ _______

A

ecological, behavioral factors

64
Q

Speciation rates are higher in what kind of populations?

A

Rates are higher in populations of species with specialized diets. For example Herbivory leads to increased speciation

65
Q

Are speciation rates higher in animal-pollinated or wind-pollinated plants?

A

Speciation rates are higher in animal-pollinated

66
Q

Are speciation rates higher in sexual or asexual selection

A

sexual selection

67
Q

Define Sexual dimorphic

A

when male and females of the same
species look different)
- increase speciation rates

68
Q

Define Polygynous

A

one male
mating with many different females
- increase speciation rates

69
Q

True or False: Rapid speciation leads to evolutionary radiation

A

True

70
Q

Define: evolutionary radiation

A

is the proliferation of a large number of
species from a single ancestor

71
Q

When does evolutionary radiation occur?

A

Occurs when species colonize new areas that contain no other closely related species

72
Q

define adaptive radiation

A

If the resulting species from an evolutionary radiation live in a wide array of environments, it is called an adaptive radiation

73
Q

Given and example of a adaptive radiation

A

Example: Hawaiian silverswords; the plants shown here are more closely related than
they appear to be based on their morphology

Biology 106; Exam #2 (4 decks)

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