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BIOL 1105 > 21: Mechanisms of Evolutionary Change > Flashcards

21: Mechanisms of Evolutionary Change Flashcards

Module 4, Lesson 4

1
Q

Generally, evolution is defined as…

A

A change in a population of organisms over time

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2
Q

In biology, evolution is defined as…

A

A change in allele frequencies in a population over time

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3
Q

True or false:

Individuals can evolve.

A

False

Evolution only occurs at the population level

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4
Q

The presence of different alleles in a population is called…

A

Genetic variation

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5
Q

True or false:

Genetic variation is necessary for evolution to occur.

A

True

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6
Q

____ can also be defined as the result of any process that changes the genetic composition of a population over time.

A

Evolution

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7
Q

List four areas of variation that can be observed in a population.

A
  1. Morphology
  2. Genes
  3. Proteins
  4. Genomes
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8
Q

____ occurs when a population has individuals with many different alleles for the same gene, resulting in a range of phenotypes.

A

Polymorphic variation

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9
Q

The ____ is the genetic constitution or makeup of an individual.

A

Genotype

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10
Q

The ____ is an individual’s apparent characteristics.

A

Phenotype

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11
Q

A primary focus of evolutionary biology is understanding….

A

The mechanisms of evolution

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12
Q

List five mechanisms of evolution.

A
  1. Mutation
  2. Gene flow
  3. Genetic drift
  4. Selection
  5. Nonrandom mating
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13
Q

True or false:

Mechanisms of evolution can act over both short and extremely long timescales.

A

True

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14
Q

A ____ is any change in the base sequence of DNA.

A

Mutation

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15
Q

The ultimate source of genetic variation is…

A

Mutation

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16
Q

True or false:

Mutations are the primary cause of changes in allele frequency within a population.

A

False

They are extremely rare, so the other processes play a bigger role

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17
Q

The movement of alleles from one population to another is called…

A

Gene flow

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18
Q

List two ways in which gene flow can occur.

A
  1. An organism moves to a new location
  2. An organism mates with a member of a different population
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19
Q

Gene flow can result in…

(two)

A
  1. The introduction of new alleles into a population
  2. A shift in allele frequencies
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20
Q

A change in allele frequencies due to “sampling error” (random chance) is called…

A

Genetic drift

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21
Q

Genetic drift has the greatest effect on ____ populations.

A

Small

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22
Q

True or false:

With enough time, genetic drift alone can cause substantial changes in allele frequencies.

A

True

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23
Q

As a result of genetic drift, two small, isolated populations may…

A

Differ genetically even without natural selection

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24
Q

List two results of genetic drift.

A
  1. Some alleles will build up (fixation) and others will be lost.
  2. The frequency of heterozygotes declines
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25
Q

The ____ occurs when a new population is established by a small number of individuals.

A

Founder effect

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26
Q

A population that experiences founder effect will…

A

Have a different allele frequency compared to the parent population

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27
Q

What happens if a founding individual carries a rare allele?

A

The new population has a higher frequency of that allele than the original population

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28
Q

The founder effect is common in ____, because generally only a small number of individuals were involved in colonization.

A

Island populations

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29
Q

The ____ occurs when a population loses genetic variation due to a drastic reduction in size.

A

Bottleneck effect

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30
Q

In both the founder effect and the bottleneck effect, the alleles found in the new population…

A

May not represent all the alleles found in the original population

31
Q

The bottleneck effect is often a problem in…

A

Populations of endangered species

32
Q

True or false:

Even if the population of a critically endangered species rebounds, the species will still have lost significant genetic variation.

A

True

33
Q

The number of offspring that an organism leaves behind is affected by…

A

Phenotype and behavior

34
Q

Charles Darwin suggested ____ as the mechanism of evolution.

A

Natural selection

35
Q

List three main points of Darwin’s theory of natural selection.

A
  1. More individuals of a species are born than can possibly survive
  2. Individuals that have profitable variations are more likely to survive and reproduce
  3. Any selected variation will propagate its modified form
36
Q

List three conditions that must be met for natural selection to occur.

A
  1. Variation in individuals
  2. Differences in rates of survival and reproduction
  3. Heritability of variations
37
Q

Individuals with that are more successful at surviving and reproducing are said to have higher…

A

“Fitness”

38
Q

True or false:

Natural selection states that survival and reproduction are random.

A

False

39
Q

According to natural selection, individuals with more favorable variations will…

A

Be better at surviving and reproducing
(will be naturally selected)

40
Q

____ occurs when environmental conditions affect which individuals produce the most offspring.

A

Natural selection

41
Q

The outcome of natural selection depends on ____ and ____.

A

Fitness and allele frequency

42
Q

True or false:

A strong fitness effect can act quickly even with small differences in allele frequencies.

A

True

43
Q

True or false:

Evolutionary forces act independently of one another.

A

False

44
Q

Evolutionary forces can work ____ or ____.

A

Together or in opposition

45
Q

____ and ____ can counter selection.

A

Mutations and genetic drift

46
Q

Gene flow can either promote or prevent…

A

Evolutionary change

47
Q

Selection may be hindered if less-favored alleles…

A

Are constantly being introduced

48
Q

____ occurs when humans select for certain characteristics in a population.

A

Artificial selection

49
Q

Artificial selection is also sometimes called…

A

Selective breeding

50
Q

True or false:

The terms “evolution” and “natural selection” can be used interchangeably.

A

False

51
Q

____ is the process that leads to evolution.

A

Natural selection

52
Q

____ is the historical record of change through time, and the outcome of natural selection.

A

Evolution

53
Q

Evolutionary mechanisms work together to change…

A

Allele frequencies over time

54
Q

In small populations, genetic drift can lead to the ____ of a mutation.

A

Loss

55
Q

Natural selection can cause elimination or promotion of a…

A

Phenotype
(and the corresponding mutation)

56
Q

The combination of survival, mating success, and the number of offspring per mating is referred to as…

A

Fitness

57
Q

Natural selection is heavily influenced by the…

A

Environment

58
Q

True or false:

It is possible that a trait might be selected for in one habitat and selected against in another.

A

True

59
Q

True or false:

It is possible to observe natural selection occuring.

A

True

60
Q

A common trait used to study natural selection is…

A

Guppy color variation

61
Q

Guppy populations in ____ environments display more spots and brighter colors after several generations.

A

Low-predator

62
Q

Guppy populations in ____ environments display dull colors after several generations.

A

Predator-containing

63
Q

____ from predators plays a role in guppy coloration.

A

Natural selection

64
Q

The ____ seeks to explain why the original proportions of genotypes remain constant in a population over time.

A

Hardy-Weinberg Principle

65
Q

Hardy and Weinberg were led to investigate why populations retain multiple alleles by…

A

The rediscovery of Mendel’s work

66
Q

According to the Hardy-Weinberg principle, what five conditions must be met for the proportions of genotypes in a population to remain constant?

A
  1. No mutation takes place
  2. No genes are transferred to or from other sources
  3. Mating is random
  4. The population size is very large
  5. No selection occurs
67
Q

When the proportion of genotypes does not change, a population is said to be in…

A

Hardy-Weinberg equilibrium

68
Q

The Hardy-Weinberg principle is used to detect…

A

Whether evolutionary processes are underway in a population

69
Q

If no evolutionary forces are acting on a population, it will…

A

Remain in Hardy-Weinberg equilibrium

70
Q

For a population that is not in equilibrium, the type of evolutionary processes taking place can be studied by…

A

Examining the changes in allele frequencies

71
Q

List three areas that stand to benefit from increased understanding of evolution.

A
  1. Medicine
  2. Conservation
  3. Agriculture
72
Q

How does understanding evolution benefit the medical field?

(two items)

A
  1. Studying antibiotic resistance
  2. Understanding evolution of infectious diseases
73
Q

How does understanding evolution benefit conservation efforts?

(four items)

A
  1. Defining species of conservation concern
  2. Understanding problems of small populations
  3. Understanding how species go extinct
  4. Finding ways to prevent extinction
74
Q

How does understanding evolution benefit agriculture?

(three items)

A
  1. Improving artifical selection
  2. Studying pesticide resistance
  3. Creating genetically modified organisms

BIOL 1105 (26 decks)

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