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Biology 1407 > Chapter 23 Evolution of Populations > Flashcards

Chapter 23 Evolution of Populations Flashcards

1
Q

Do organisms evolve during their lifetimes?

A

No, only natural selection

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2
Q

What does natural selection act on?

A

Genetic variation, different phenotypes.

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3
Q

Can populations evolve?

A

Yes

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4
Q

*there must be a change in ___________ for evolution to take place

A

Allele frequencies

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5
Q

What is a change in allele frequency‘s in a population over generations?

A

Microevolution

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6
Q

In microevolution what are the three mechanisms that cause allele frequency change?

A

-natural selection -genetic drift -Gene flow

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7
Q

Only ___________ causes adaptive evolution

A

Natural selection

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8
Q

What is the mechanism that improves the match between the organism and its environment?

A

Natural selection

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9
Q

What is the mechanism that can cause a change in the gene pool of a small population strictly by chance?

A

Genetic drift

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10
Q

The transfer of genetic variation from one population to another coming or leaving the population

A

Gene flow

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11
Q

What is a prerequisite for evolution?

A

Genetic variation in heritable traits

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12
Q

Genetic variation among individuals is caused by ____________.

A

Differences in genes or other DNA segments

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13
Q

What contributes to phenotypic differences?

A

Single gene or Two or more genes (quantitative characters)

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14
Q

Average heterozygosity measures the average percent of loci that are heterogeneous in a population

A

Gene variability *more valuable measurement compared to nucleotide variability

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15
Q

Measured by comparing the DNA sequence of pairs of individuals

A

Nucleotide variability

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16
Q

How do you new genes and alleles arise?

A

-mutation -gene duplication -exon shuffling

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17
Q

What are other sources of genetic variation?

A

-horizontal gene transfer -sexual reproduction

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18
Q

-a change in nucleotide sequence of DNA

A

Mutation

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19
Q

Only mutations in cells that produce ________ can be passed offspring

A

Gametes (egg or sperm)

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20
Q

What is a change in one base in a gene?

A

Point mutation

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21
Q

Why can mutations to genes be neutral?

A

No change to the amino acid being made, it’s silent no change in the phenotype Or mutations that occur in the introns

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22
Q

differences in DNA sequence that do not confer a selective advantage or disadvantage Ex: mutations in non-coding regions of DNA

A

Neutral variation

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23
Q

Duplicated genes can take on new __________ by further mutation Ex. Globins (hemoglobin, myoglobin)

A

Functions

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24
Q

Are mutation rates higher or lower in animals and plants? With a Mutation rate of…

A

Low 1 in every 100,000 genes per generation

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25
Q

Mutations rates are often ________ in prokaryotes and ________ in viruses

A

Lower, higher

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26
Q

Why do most mutations accumulate quickly in prokaryotes in viruses?

A

Shorter lifespan (20-30 min)

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27
Q

sexual reproduction can shuffle existing alleles into new combinations by what three ways?

A

-crossing over -independent assortment of chromosomes -fertilization

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28
Q

In organisms that reproduce sexually, _________ of alleles is more important than mutations in producing the genetic differences that make adaptation possible

A

Recombination

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29
Q

What equation is used to test whether a population is evolving?

A

Hardy-Weinberg Equation P^2 + 2pq + q^2 = 1

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30
Q

p= q= p^2= 2pq= q^2=

A

p= frequency of dominant allele q= frequency of recessive allele p^2= Frequency of AA genotype 2pq= frequency of Aa genotype q^2= Frequency of aa genotype

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31
Q

A localized group of individuals capable of interbreeding and producing fertile offspring

A

Population

32
Q

Consists of all the alleles for all loci in a population

A

Gene pool

33
Q

The Hardy-Weinberg principle describes a population that is…..

A

Not evolving

34
Q

If a population does not meet the criteria of the Hardy-Weinberg principle, it can be concluded that the population is __________

A

Evolving

35
Q

Principle that states frequencies of alleles and genotypes in a population remain constant from generation to generation

A

The Hardy-Weinberg principle

36
Q

Describes the constant frequency of alleles in a gene pool

A

Hardy-Weinberg equilibrium

37
Q

Describes a hypothetical population that is not evolving

A

The Hardy-Weinberg theorem

38
Q

*** in the Hardy-Weinberg theorem what are the five conditions for non-evolving populations (rarely met in nature)

A
  1. No mutations 2. Random mating 3. No natural selection 4. Extremely large population size 5. No gene flow
39
Q

Natural populations can evolve at some loci, while being in Hardy-Weinberg equilibrium at other loci. True or false?

A

True

40
Q

Phenylketonuria (PKU) that occurs 1 in every 10,000 births (2% of the U.S. population) is an example of ….

A

Hardy-Weinberg equilibrium

41
Q

What are the three major factors that alter allele frequencies and bring about most evolutionary change?

A

-natural selection -genetic drift -Gene flow

42
Q

How does natural selection alter allele frequency?

A

Differential success in reproduction results in certain alleles being passed to the next generation in greater proportions

43
Q

How does genetic drift alter allele frequency?

A

-changes Clearlake frequency due to random chance -describes how allele frequency‘s fluctuate unpredictably from one generation to the next

44
Q

Will a smaller or larger sample have a greater chance of deviation from a predicted result?

A

Smaller

45
Q

How does genetic drift tend to reduce genetic variation?

A

-

46
Q

What effect can be seen when a few individuals become isolated from a larger population? Can allele frequencies in this smaller population be different from those in the larger parent population?

A

The founder effect Yes, does not match the parent population

47
Q

What effect is seen when there is a sudden reduction in population size due to a change in the environment?

A

The bottleneck effect

48
Q

With the bottleneck effect, is the resulting gene pool reflective of the original populations gene pool?

A

No. There is less genetic variation than the original population. If the population remain small, it may be further affected by genetic drift

49
Q

-population reduced dramatically and then rebuilds -randomly eliminated members without regard to genotype -surviving members may have allele frequencies different from original population -Allele frequencies can drift substantially when the population is small -New population likely to have less genetic variation

A

Bottleneck effect

50
Q

Understanding the _________ effect can increase understanding of how human activity affects other species

A

Bottleneck

51
Q

Genetic drift is significant in ________ populations Genetic drift causes allele frequencies to change at __________

A

Small Random

52
Q

Genetic drift can lead to a loss of genetic _________ within populations Genetic drift can cause harmful alleles to become __________

A

variation Fixed

53
Q

Consists of the movement of alleles among populations Alleles can be transferred through the movement of fertile individuals or gametes (for example, pollen)

A

Gene flow

54
Q

* Gene flow tends to _______ variation among populations over time * tends to ________ genetic diversity within a population

A

Reduce Enhance

55
Q

Can gene flow decrease the fitness of a population?

A

It increases the fitness of the population

56
Q

Gene flow can __________ the fitness of a population

A

Increase Ex: resistance to insecticide can be passed to other populations and increase their fitness

57
Q

____________ is an important agent of evolutionary change in human populations

A

Gene flow

58
Q

______________ is the only mechanism that consistently causes adaptive evolution

A

Natural selection

59
Q

In Evolution by natural selection…. New genetic variations arise by ________ Beneficial alleles are “_______” and favored by natural selection

A

Chance Sorted

60
Q

Leaving genes for the next generation The contribution of an individual makes to the gene pool for the next generation, relative to the contributions of other individuals

A

Relative fitness

61
Q

Selection favors certain genotypes by acting on what of individuals?

A

Phenotypes

62
Q

What are the three modes of selection?

A

-directional selection -destructive selection -stabilizing selection

63
Q

A mode of selection that favors individuals at one end of the phenotypic range (an extreme is picked)

A

Directional selection

64
Q

Selection that favors individuals at both extremes of the phenotypic range

A

Disruptive selection

65
Q

Mode of selection that favors intermediate variance and acts against extreme phenotypes

A

Stabilizing selection

66
Q

Does genetic drift and gene flow consistently lead to adaptive evolution?

A

No. They can increase or decrease the match between the organism and it’s environment

67
Q

natural selection for mating success

A

Sexual selection This can cause sexual dimorphism

68
Q

the differences in secondary sexual characteristics between males and females of the same species

A

Sexual dimorphism

69
Q

Selection within the same sex, individuals of one sex compete directly for mates of the opposite sex.

A

Intrasexual selection

70
Q

Also called mate choice, one sex is choosy in selecting their mates from the other sex

A

Intersexual selection

71
Q

Balancing selection includes…

A

-heterozygote advantage (ex: malaria protection in heterozygous for sickle cell) -frequency-dependent selection

72
Q

Occurs when natural selection maintain stable frequencies of two or more phenotypic forms in a population

A

Balancing selection

73
Q

-occurs when heterozygotes have a higher fitness then do both homozygotes -natural selection will tend to maintain two or more alleles at that locus -can result from stabilizing or directional selection

A

Heterozygote advantage

74
Q

The fitness of a phenotype declines if it becomes too common in the population Selection can favor which ever phenotype is less common in a population Selects for approximately equal numbers Ex: right-mouth and left-mouth fish

A

Frequency-dependent selection

75
Q

Genetic variation that does not confer a selective advantage or disadvantage

A

Neutral variation

Biology 1407 (22 decks)

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