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Baby Bio > Chap 12 Forces of Evolutionary Change > Flashcards

Chap 12 Forces of Evolutionary Change Flashcards

1
Q

Evolution occurs in…?

A

populations

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2
Q

Evolution does not occur in…?

A

individuals

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3
Q

Why does evolution not occur in individuals?

A

because an individuals alleles do not change

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4
Q

In a population what changes from one generation to the next?

A

allele frequencies (some become more common, some less common)

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5
Q

Whose voyage provided evidence for evolution?

A

Darwin’s

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6
Q

What were the ideas of evolution Darwin came up with?

A

descent with modification

natural selection

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7
Q

What changes allele frequencies?

A

artificial selection

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8
Q

What gave Darwin the idea for natural selection as an evolutionary force?

A

artificial selection/selective breeding

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9
Q

How do humans alter allele frequencies?

A

artificially

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10
Q

What happens in artificial selection?

A

a human chooses desired features, then allows only the individuals that best express those qualities to reproduce. This increases the frequency of the desired alleles in the population

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11
Q

Darwin proposed what as a mechanism for evolution?

A

natural selection

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12
Q

What were the observations of nature?

A

genetic variation
limited resources
overproduction of offspring

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13
Q

What were the inferences from observations?

A

struggle for existence

unequal reproductive success (natural selection)

descent with modification

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14
Q

What is descent with modification?

A

over many generations, a population’s characteristics can change by natural selection, even giving rise to new species

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15
Q

What is overproduction of offspring?

A

more individuals are born than survive to reproduce

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16
Q

What are the common misconception of evolution theory?

A

explains the origin of life

it is a random process

in all changing environments all individuals in a population simultaneously develop beneficial adaptations

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17
Q

What is the answer to the misconception that biological evolution explains the origin of life?

A

biological evolution did not begin until life existed

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18
Q

What is the answer to the misconception that evolution is a random process?

A

some mechanisms of evolution, such as mutations, do occur randomly. Natural selection, however, is nonrandom because the environment selects against poorly adapted individuals.

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19
Q

What is the answer to the misconception that in all changing environments all individuals in a population simultaneously develop beneficial adaptations?

A

adaptations become “fixed” in a population over multiple generation, as individuals with beneficial adaptations are most likely to survive, reproduce, and pass their genes to the next generation

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20
Q

What molds evolution?

A

Natural selection

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21
Q

Natural selections doe not…?

A

create alleles (instead, it strongly selects for alleles that arise by chance)

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22
Q

What enhances reproductive success?

A

adaptations

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23
Q

What are adaptations?

A

heritable features that improve an organism’s ability to survive and reproduce (e.g. some people produce more gametes than others)

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24
Q

What does not constitute evolution?

A

short-term changes in an individual

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25
Q

What creates natural selection for resistant bacteria?

A

antibiotics (bacteria that are resistant to antibiotics have an adaptive trait that nonresistant bacteria lack. When antibiotics are present, the resistant bacteria can survive and reproduce better then the others)

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26
Q

What eliminates poorly adapted phenotypes?

A

natural selection (as environmental conditions change, the phenotypes that natural selection favors will also change. Adaptations that seem “perfect” in one environment would be completely wrong in another)

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27
Q

What can eliminate entire species?

A

natural selection

28
Q

How can natural selection eliminate entire species?

A

if the right alleles aren’t available at the right time, an environmental change may wipe out a species

29
Q

Evolution does not have a what?

A

goal (an orchid and wasp pollinator have evolved along side each other. But the orchid does not evolve in order to be better-pollinated by the wasp. the wasps created a selective advantage for orchids with just the right shape for wasps)

30
Q

What is fitness?

A

reproductive success

31
Q

By itself, what is not enough for evolutionary fitness?

32
Q

Fitness depends on what?

A

the ability to reproduce (the organism’s genetic contribution to the next generation)

33
Q

What is unavoidable?

34
Q

Why is evolution unavoidable?

A

in real populations, allele frequencies will inevitably change over time because they are affected by so many selective forces

35
Q

Can scientists test evolution?

36
Q

How do scientists test evolution?

A

test evolution and measure allele frequencies do or do not change from one generation to the next

37
Q

What doe Hardy-Weinberg equilibrium rely on?

A

assumption about the population

38
Q

What assumptions need to be met for a population to be at Hardy-Weinberg equilibrium?

A 
random mating
no migration
no genetic drift
no mutation
no natural selection
(basically the allele frequencies do not change)
39
Q

We can calculate what?

A

allele and genotype frequencies

40
Q

What must be met to get equations representing the relationship between allele frequencies and genotype frequencies?

A

Hardy-Weinberg equilibrium

41
Q

What always changes?

A

allele frequencies

42
Q

What is always violated in real populations and what does this mean?

A

the assumption of Hardy-Weinberg equilibrium

evolution is taking place

43
Q

Natural selection can shape what?

A

populations

44
Q

What are the different types of natural selection?

A

directional selection
disruptive selection
stabilizing selection

45
Q

Directional selection favors what?

A

favors one phenotype over another (e.g. darker tree color allows darker moths to survive and reproduce more than light moths. over time dark moths become more frequent in the population)

46
Q

Disruptive selection favors what?

A

extreme phenotypes (e.g. the light and dark rocks allow light and dark snails to survive and reproduce more than the intermediate colored snails. over time the medium snails become less frequent in the population)

47
Q

Stabilizing selection favors what?

A

intermediate phenotypes (e.g. health problems allow medium-sized babies to survive and reproduce more than the very large or very small babies. over time medium-sized babies become more frequent in the population)

48
Q

Why are harmful alleles sometimes maintained in a population?

A

heterozygote advantage (in which a heterozygote is favored over homozygotes)

49
Q

Sickle cell heterozygotes are resistant to what?

50
Q

Where are sickle-celled alleles more frequent?

A

parts of the world where catching malaria is common

51
Q

Sickle cell alleles confer what when malaria is a threat?

A

heterozygote advantage

52
Q

Heterozygotes of the sickle cell alleles do not have/protect against what?

A

don’t have sickle cell disease

protect against malaria

53
Q

Is it possible for the offspring of two heterozygotes to have sickle cell disease?

A

yes (25% each time)

54
Q

What directly influences reproductive success?

A

sexual selection

55
Q

Can sexual selection favor traits that apparently reduce survival?

56
Q

What causes evolution to occur?

A

mutations

gene flow

57
Q

Mutations create what?

A

genetic diversity

58
Q

How does mutation cause evolution?

A

beneficial mutations are passed on to the next generation, so their frequency increases over generations

59
Q

What is genetic drift?

A

sampling error

60
Q

How does genetic drift occur?

A

sometimes by random, only some individuals in a population reproduce causing a change in allele frequency to occur purely by chance

61
Q

What causes genetic drift?

A

the founder effect

population bottlenecks

62
Q

What is the founder effect?

A

when a few individuals migrate away to establish a new population, the allele frequency might change

63
Q

What causes population bottleneck?

A

if the size of the population becomes greatly reduced. genetic diversity in the new population decreases as many of the alleles are lost. only the alleles in the surviving individuals will be maintained

64
Q

What is gene flow?

A

moves alleles between populations and increases the genetic diversity. this can change the allele frequencies in both populations

65
Q

Why study evolution?

A

it is based on a wide range of evidence

it offers an explanation for life’s diversity- the features seen in all different organisms on earth

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