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Chapter 12 Flashcards

The Forces of Evolutionary Change (81 cards)

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1
Q

Define evolution

A

-descent with modification
-change in allele frequencies in a population over time
-it explains the feature of all organisms, from microbes to humans

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2
Q

Evolution is genetic change over time

A

-evolution occurs when there are changes in heritable traits from generation to generation
-some changes lead to development of different species

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3
Q

Evolution occurs in populations (not individuals)

A

-evolution doesn’t occur in individuals because their alleles do not change
-in a population, allele frequencies change from one generation to the next, over time
-some alleles become more commons in a population, others less common

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4
Q

Allele frequencies vary between populations

A

-in the population of Asia, the frequency of alleles that produce black hair is high
-in the population of Sweden, the frequency of alleles the produce black hair is low
-if Swedish people migrate to Asia and interbreed with local people, the allele frequencies in the gene pool of Asia would change (evolution will have occurred)

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5
Q

Define allele frequency

A

-the number of copies of 1 allele divided by the total number of alleles in a population
-6/50=0.12
-44/50=0.88

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6
Q

Define gene pool

A

-all of the genes and their alleles in a population

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7
Q

Define population

A

-interbreeding members of the same species occupying the same region

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8
Q

Define microevolution

A

-small generation by generation changes to a population’s gene pool

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9
Q

Define macroevolution

A

-large scale evolutionary events, such as the appearance of new species

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10
Q

1785 James Hutton

A

-uniformitarianism: the changes in nature are gradual

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11
Q

1798 Georges Cuvier

A

-catastrophism: brief, violent events produce changes in nature
-species reappear after catastrophes
-fossils represent extinctions

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12
Q

1809 Jean Baptiste De Lamarck

A

-proposed testable ideas about how species change
-new species come from existing species through environmental forces

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13
Q

1830 Charles Lyell

A

-earth must be very old, since natural processes occur over time
-all changes in nature are gradual (renewed uniformitarianism)
-earth is 6,000+ years old

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14
Q

Fossils provide evidence for slow changes over time

A

-studying geology demonstrates Cuvier’s principle of superstition
-fossils of extinct species in old layers of rock suggest that living organisms evolved from common ancestors

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15
Q

Georges Louis Buffon

A

-one of the first to openly suggest that closely related species arose from a common ancestor and were changing

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16
Q

Define uniformitarianism

A

-suggest that the process of erosion and sedimentation that occur now also occurred in the past, producing profound changes in earth over time
-James Hutton 1785

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17
Q

Define catastrophism

A

-the idea that brief upheavals such as floods, volcanic eruptions, and earthquakes are responsible for most geological formations
-Georges Cuvier 1798

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18
Q

Define principle of superposition

A

-the idea that lower layers of rock (and the fossils they contain) are older than the ones above

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19
Q

Darwin’s voyage provided evidence for evolution

A

-HMS Beagle ship
-Charles Darwin documented the great variety of organisms in South America and their relationships to fossils and geology
-he began to think these were clues to how new species originate

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20
Q

Darwin proposed the idea of decent with modification

A

-Charles Darwin studies finches in the Galapagos Islands
-he saw that their beaks types matched up with the foods they ate
-Darwin though the different finch species all descended from the same finch ancestor

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21
Q

Darwin proposed the idea of natural selection

A

-Charles Darwin saw that the environment of each island influenced the survival and reproduction of the finches living there
-finches with features best suited to the environment were able to survive and reproduce better than the others

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22
Q

Observations of nature

A

1.) genetic variation- within a species, no 2 individuals (except identical siblings) are exactly alike. Some of this variation is heritable
2.) limited resources- every habitat contains limited supplies of resources required for survival
3.) over production of offspring- more individuals are born than survive and reproduce

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23
Q

Inferences from observations

A

1.) struggle for existence- individuals compete for the limited resources that enable them to survive
2.) unequal reproductive success (natural selection)- the inherited characteristics of some individuals make them more likely to obtain resources, survive and reproduce
3.) descent with modification- over many generations, a population’s characteristics can change by natural selection, even giving rise to new species

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24
Q

Define natural selection

A

-occurs when individuals with certain genotypes (those that are best suited for the environment) have greater reproductive success then other individuals
-artificial selection is faster than natural selection

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25
Artificial selection (aka selective breeding) changes allele frequencies
-wild mustard plant populations show a variety of different traits -plant breeders bred mustard plants with they traits they linked, leading to different vegetable varieties -artificial selection (aka selective breeding) also helped Darwin form the theory of evolution by natural selection
26
Humans artificially alter allele frequencies
-in artificial selection, a human chooses desired features, then allows only the individuals that best express those qualities of the desired trait to reproduce -this increases the frequency of desired alleles in a population -it may also amplify the frequency of undesired alleles associated with hereditary health problems (like extensive inbreeding of purebred dogs)
27
Evolutionary theory is supported by data
-over the years, a large body of careful research has corroborated and expanded on Darwin's findings
28
Define modern evolutionary synthesis
-the idea that genetic mutations create the heritable variation upon which natural selection acts
29
Natural selection molds evolution
-natural selection doesn't create alleles. instead, it strongly selects for alleles that arise by chance -each generation, the best camouflaged seahorses survive and reproduce -the alleles conferring camouflage became more frequent in each generation
30
Natural selection required genetic variation
-since more individuals are born than resources can support, the struggle to survive is inevitable -some individuals in a population are better than other at surviving and reproducing
31
Adaptations exchange reproductive success
-adaptations are heritable features that provide a selective advantage because they improve an organism's ability to survive and reproduce -this flower tastes bad, so the plant is not eaten by predators
32
Bacteria undergoes natural selection
-bacteria that are resistant to antibiotics have an adaptive trait that nonresistant bacteria lack -when antibiotics are administered, resistant bacteria survive and reproduce while nonresistant bacteria no not
33
Resistant bacteria become more frequent on the population over time
-antibiotics can't create a resistant allele. the variation in resistance was already present in the population
34
Adaptations enhance reproductive success
-the porcupine fish is a medium sized fish that can't swim very fast. when threatened, it inflates with its sharp spines -these defense are adaptation, heritable traits that increase the chances that the fish will survive long enough to reproduce
35
Evolution never stops
-as environmental conditions change, the phenotypes that natural selection favors will also change -adaptation that seem "perfect" in one environment would be completely wrong in another
36
Evolution doesn't have a goal
-this orchid and its wasp pollinator have evolved alongside one another long enough that no other animal can pollinate that flower -the orchid doesn't evolve in order to be better pollinated by the wasp. neither the orchid not natural selection has foresight
37
Evolution keeps the "best" alleles in the population
-instead, orchids that are best suited to wasp pollination are most likely to reproduce, so their alleles get passed onto the next generation most often
38
Survival of the "fittiest"
-fitness describes and organism's genetic contribution to the next generation -orchids that are best suited to wasp pollinate are the most "fit" because they are most likely to reproduce, so their alleles get passed to the next generation most often
39
Misconception: biological evolution explains the origin of life
-Biologists' explanation: biological evolution didn't begin until life existed
40
Misconception: evolution is a random process
-Biologists' explanation: some mechanisms of evolution, such as mutations, do occur randomly. Natural selection, however, is nonrandom because the environment selects against poorly adapted individuals
41
Misconception: in a changing environment, all individuals in a population simultaneously develop beneficial adaptations
-Biologists' explanation: adaptations become "fixed" in a population over multiple generations, as individuals with beneficial adaptations are most likely to survive, reproduce, and pass on their genes to the next generation
42
Fitness is reproductive success
-fitness includes surviving, reproducing, and having offspring that survive to reproduce -even if an organism doesn't survive, fitness means that its alleles will
43
Scientists can test evolution
-scientists test evolution against a null hypothesis, which states that allele frequencies do not change from one generation to the next
44
Evolution is not only possible, it's inevitable
-in this ferret population, the alleles D & d confer a phenotype of fur color -D (dark fur) is dominant over d (light fur) -64/100 ferrets have dark fur -36/100 ferrets have light fur -hardy Weinberg equilibrium is the unlikely situation in which allele frequencies do not change between generations
45
Do allele frequencies change at equilibrium?
-no, the allele frequencies stay the same
46
Hardy Weinberg equilibrium occurs only if a population meets all of these assumptions
1.) natural selection does not occur 2.) no mutations 3.) the population is large enough to eliminate random changes in allele frequencies 4.) individuals mate at random 5.) no migration
47
Assuming the assumptions of Hardy Weinberg equilibrium are met, 2 calculations represent the relationship between allele frequencies and genotype frequencies
p= frequency of dominant allele q= frequency of recessive allele p + q = 1 p^2 + 2pq = q^2 = 1
48
Scientists count up the alleles to calculate the frequencies
-since D gene has 2 alleles, the frequencies of the dominant plus the recessive must equal 1
49
Scientists count up the alleles to calculate the frequencies -DD
-DD: multiplying the frequency of the dominant allele by itself gives the frequency of homozygous dominant individuals in the next generation p^2 = (0.6)^2 = 0.36
50
Scientists count up the alleles to calculate the frequencies- dd
-dd: multiplying the frequency of the recessive allele by itself gives the frequency of homozygous recessive individuals in the next generation q^2 = (0.4)^2 = 0.16
51
Scientists count up the alleles to calculate the frequencies- Dd
-Dd: the frequency of the dominant alleles multiplied by the frequency of the recessive allele gives the frequency of heterozygous individuals in the next generation pq = (0.6)x(0.4) = 0.24 -this equation is twice in a Punnett square so add up the totals together 0.24 + 0.24 = 0.48 Dd
52
Hardy Weinberg is a useful model. But in real populations, the assumptions of Hardy Weinberg are always violated
1.) natural selection and mutations do occur 2.) random changes in allele frequencies are common 3.) individuals rarely mate at random 4.) there is always some level of migration between populations
53
Define Hardy Weinberg equilibrium
-a situation in which allele frequencies and genotype frequencies do not change from one generation to the next -Godfrey H. Hardy and Wilhelm Weinberg
54
Natural selection can shape populations in many ways
-3 modes of natural selection: directional, disruptive, and stabilizing are distinguished by their phenotypes in a population
55
Define directional selection
-favors one phenotype over another -ex. the black moths survive and reproduce more than the light moths
56
Define disruptive selection
-favors 2 or more extreme phenotypes -aka diversifying selection -ex. very light and very dark snails both survive and reproduce more than the intermediate colored snails
57
Define stabilizing selction
-favors intermediate phenotypes -most common in stable, unchanging environments -ex. baby weight: if baby is born too small or too large, they are less likely to survive
58
Why are harmful alleles sometimes maintained in a population?
-one explanation for why harmful alleles persist in a populations is heterozygote advantage in which a heterozygote is favored over homozygotes -the sickle cell allele is harmful (causes sickle cell disease: SCD)
59
Sickle cell allele confers heterozygote advantage
-ex. heterozygotes for the sickle cell allele do not have sickle cell disease and are protected against malaria -but if 2 heterozygotes mate, their child might have sickle cell disease (a 25% chance)
60
Define balanced polymorphism
-a condition in which multiple alleles for the same gene persist indefinitely in a populations
61
Define heterozygote population
-a condition in which a heterozygote has greater fitness than homozygotes, maintaining balanced polymorphism in a population
62
Sexual selection directly influences reproductive success
-building complex nests, flashy showing plumage, and butting heads with rivals males and all appear to waste energy -how can natural selection allow for traits that apparently reduce survival
63
Sexual selection is a type of natural selections
-sexual selection results from variation in the ability to obtain mates (intrasexual and intersexual) -sexual selection results from from either competition for access to the other sex or from one sex choosing attractive mates of the other text
64
Define intrasexual selection
-intrasexual selection occurs when the stronger individuals in a population battle to win access to mates (competition among themselves for mates) -the weaker of the individuals are denied access
65
Define intersexual selection
-intersexual selection occurs when members of one sex choose mates with the highest quality features
66
Define sexual dimorphism
-the difference in appearance between males and females
67
Sexual selection causes evolution to occur
-individuals with the sexually selected traits mate the most, and therefore pass along their genes the most -mating is not random
68
Mutations cause evolution to occur
-mutations cause genetic diversity -mutations are random changes in the sequence of DNA. They can be harmful, but many are harmless and some are beneficial -beneficial mutations are passed on to the next generation, so their frequency increases over generations
69
Genetic drift causes evolution to occur
-genetic drift is a random sampling error. Allele frequencies can shift dramatically, and often become more eliminated, when only a part of a population survives to reproduce
70
The founder effect causes genetic drift
-when only a few individuals establish a new population, the allele frequencies might change. This process illustrates the founder effect
71
Population bottleneck causes genetic drift
-a population bottleneck occurs is a disaster drastically reduces the size of a population
72
Nonrandom mating causes evolution to occur
-sexual selection and artificial selection can alter mating patterns in a population, preventing random mating
73
Gene flow causes evolution to occur
-gene flow moves alleles between population. This might affect the frequencies in both populations -migration causes gene flow and ultimately reduces genetic differences between populations
74
Define genetic drifts
-aka sampling drift -change in allele frequency that occurs purely by chance
75
Define founder effect
-genetic drift that occurs when a small, nonrepresentative group of individuals leaves their ancestral population and begins a new settlement (small migration)
76
Define bottleneck effect
-genetic drift that occurs as a result of a sudden reduction in the size of a population
77
Define gene flow
-movement of alleles from one population to another
78
Define nonrandom mating
-choosing mates based on location, physical traits, or other factors
79
Investigating life: size matters in fishing frenzy
-evolution by means of natural selection has practical applications, such as establishing fishing regulations -for years, humans have been removing only the large fish from the population
80
Investigating life: fish harvesting affects average fish size
-researchers have established 3 populations and applied the following treatments 1.) removing large fish 2.) removing random fish 3.) removing small fish
81
Investigating life: large fish harvesting selects for small size
-after just 4 generations, evolution could be measured -the large harvested had a much lower average weight than the small harvest population -the frequency of alleles for large size

Principles of biology (12 decks)

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