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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

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
19
Q

Gene flow can result in…

(two)

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

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

A

Genetic drift

21
Q

Genetic drift has the greatest effect on ____ populations.

A

Small

22
Q

True or false:

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

A

True

23
Q

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

A

Differ genetically even without natural selection

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
25
Q

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

A

Founder effect

26
Q

A population that experiences founder effect will…

A

Have a different allele frequency compared to the parent population

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

28
Q

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

A

Island populations

29
Q

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

A

Bottleneck effect

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

BIOL 1105 (21 decks)

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