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BIOL 1240 > exam 3 ppt 8 > Flashcards

exam 3 ppt 8 Flashcards

1
Q

5 assumptions of HWE

A

mate at random, no natural selection, no genetic drift, no gene flow, no mutation

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2
Q

what was charles darwin’s book on evolution?

A

On the Origin of Species (about natural selection)

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3
Q

what did Darwin and Wallace do?

A

they independently came to describe natural selection

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4
Q

definition of artificial selection

A

describes how humans have modified species for desired traits over many generations

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5
Q

which type of selection is due to human manipulation?

A

artificial selection

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6
Q

what did Darwin base his theory called natural selection on?

A

he based it on the principles of artificial selection

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7
Q

definition of fitness

A

those best adapted to an environment would be most successful at passing on their genes to the next generation

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8
Q

what does natural selection do?

A

natural selection acts over generations to increase the fitness of a population

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9
Q

definition of adaptation

A

any heritable trait that increases the fitness of an individual relative to those lacking the trait

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10
Q

did Darwin and Wallace ultimately publish together?

A

yes

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11
Q

how many postulates does natural selection have?

A

4

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12
Q

4 postulates of natural selection (listed)

A

1) variation exists in populations, 2) some of the differences in traits are heritable, 3) survival and reproductive success is variable, 4) the individuals that have the highest survival and the highest number of offspring are not random

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13
Q

1st postulate of natural selection

A

variation exists in populations

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14
Q

2nd postulate of natural selection

A

some of the differences in traits are heritable

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15
Q

3rd postulate of natural selection

A

survival and reproductive success is variable

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16
Q

4th postulate of natural selection

A

the individuals that have the highest survival and the highest number of offspring are not random

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17
Q

what is another name for natural selection?

A

survival of the fittest

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18
Q

definition of survival of the fittest (natural selection)

A

the more prolific reproduction of individuals with favorable traits (adaptations) that survive environmental change because of those traits; this leads to evolutionary change

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19
Q

what different characteristics can natural selection be?

A

it can be stabilizing, directional, or diversifying- acting on a phenotype

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20
Q

definition of directional selection

A

changes the average phenotype of a population in one direction (skewing one way or another)

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21
Q

definition of stabilizing selection

A

reduces both extreme phenotypes in a population

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22
Q

definition of disruptive selection

A

eliminates average phenotypes and favors extremes

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23
Q

definition of balancing selection

A

maintains variation in the population; no phenotype is favored; favors variation

24
Q

exp of disruptive selection

A

beak length in Darwin’s finches- only birds with short or extremely long beaks survived long enough to reproduce (intermediates didn’t have any food to eat in drought, died)

25
Q

could selection lead to the formation of a new species?

A

yes

26
Q

in directional selection, genetic variation is…

A

reduced

27
Q

in stabilizing selection, genetic variation is…

A

reduced

28
Q

in disruptive selection, genetic variation is…

A

increased (selecting for two different phenotypes, the extremes)

29
Q

in balancing selection, genetic variation is…

A

maintained

30
Q

natural selection works by acting on ….

A

genetic variation

31
Q

as a result of natural selection acting on phenotypic variation, the _______ also changes

A

frequency of alleles

32
Q

exp of how the frequency of alleles changes with natural selection

A

rock pocket mice- increase for dark fur, decrease for light fur

33
Q

huntington’s disease is caused by a dominant lethal mutation, the allele H. if having the H allele leads to death, what would you expect to see happen to the H allele over time?

A

the allele is still in human population because it doesn’t show up until age 30-40; if stopped during reproduction, it wouldn’t survive still

34
Q

what may occur in extreme cases of natural selection?

A

fixation

35
Q

definition of fixation

A

in natural selection, may occur where a beneficial allele has a frequency of 1 (other allele frequency is 0, only one allele present)

36
Q

definition of positive selection

A

increases the frequency of a favorable allele

37
Q

exp of positive selection

A

B allele in lava flow areas- rock pocket mice

38
Q

definition of negative selection

A

decreases the frequency of a harmful allele

39
Q

exp of negative selection

A

b allele in lava flow areas

40
Q

definition of balancing selection

A

observed when two alleles are maintained, and are more successful in different conditions (either allele can be helpful)

41
Q

what can be one explanation for balancing selection?

A

heterozygote advantage

42
Q

definition of heterozygote advantage

A

occurs when heterozygotes have a higher fitness than do both homozygotes

43
Q

exp of heterozygote advantage

A

in tropical Africa, where Malaria is common (parasite attacks red blood cells): 1) homozygous wild type individuals die of malaria (SS), 2) homozygous recessive individuals die of sickle cell anemia (ss), 3) heterozygotes are relatively free of both (Ss)- cancels each other out

44
Q

definition of sexual selection

A

promotes traits that increase an individual’s reproductive fitness, and may seem to violate natural selection

45
Q

type of sexual selection

A

sexual dimorphism

46
Q

definition of sexual dimorphism

A

distinct difference in size or appearance between the sexes of an animal in addition to differences between the sexual organs themselves; leads to them being more relroductively successful

47
Q

exp of sexual dimorphism

A

birds- color, feathers of males vs females, etc

48
Q

two broad types of sexual selection

A

intersexual selection, intrasexual selection

49
Q

definition of intersexual selection

A

(between two sexes) occurs when a mate is chosen by an individual of the opposite sex

50
Q

definition of intrasexual selection

A

(within a sex) occurs when there is a competition to obtain a mate

51
Q

exp of intrasexual selection

A

red deer males use weaponry with their antlers to compete for mates

52
Q

exp of intersexual selection

A

male birds of paradise display their feathers for females

53
Q

what is sexual selection an example of?

A

natural selection

54
Q

the varied traits we discussed are examples of…

A

adaptations

55
Q

what is the only “adaptive” type of evolution?

A

natural selection

56
Q

what types of evolution are non-adaptive?

A

mutation, genetic drift, and gene flow

BIOL 1240 (9 decks)

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