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Evolution > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q
  • two main features affecting allele frequency
A

Genetic Drift and Natural Selection

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2
Q

random, nonadaptive evolution

A

Genetic Drift

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3
Q

Happens through adaptation

A

Natural Selection

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4
Q

all genes are subject to this

A

Genetic Drift

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5
Q

all genes are not subject to this

A

Natural Selection

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6
Q

largely developed by Sewall Wright in the 30’s and Motoo Kimura in the 60’s

A

Theory of Genetic Drift

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7
Q

the difference between your sample and the real population

A

Sampling error

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8
Q

more than likely the small population will go to 0

A

Genetic Drift

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9
Q

small independent population that interbreeds with one another

A

Deme

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10
Q

set of Demes

A

Metapopulation

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11
Q

May start out the same say p=0.5
But random changes may push one way or another
One deme goes one way & another may go the other way
Thus originally identical demes may become different

A

Random Fluctuations

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12
Q

In a finite population, allele frequencies fluctuate even without NS

A

Genetic Drift

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13
Q

Some alleles fixed, others lost, homozygotes increase

A

Genetic Drift

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14
Q

Separate populations diverge

Genetic Drift

A

Genetic Drift

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15
Q

Easier to alter large or small population sizes?

A

small

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16
Q

most populations will go to..

A

fixation

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17
Q

even large populations diverge from same…

A

starting point

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18
Q

leads to homozygosity

-random, it could be good or bad

A

Fluctuations and population size

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19
Q

example of loss of Heterozygosity

A

New zealand snapper fishery

  • overexploited
  • drift taken over
  • fewer heterozygotes
  • but 3,000,000 individuals!!
  • few reproduce
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20
Q

how many bread

A

effective population size ( 200 in new zealand fishery )

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21
Q

will alter it - only large ones mate for example

A

Natural Selection

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22
Q

may allow offspring to mate with parents

A

Overlapping generations

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23
Q

small repeats in DNA

A

Microsatallites

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24
Q

evolve rapidly, and selectively neutral

A

Microsatallites

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25
Q

can track population

A

Microsatallites

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26
Q

formed from slippage-induced mutation

A

Microsatallites

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27
Q

sea levels down, islands connected

A

Glaciation

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28
Q

drift is stronger in small populations?

A

true

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29
Q

history of a particular gene

A

Gene trees

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30
Q

Looking backwards, the alleles come together (coalesce) to a single individual

A

Coalescence

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31
Q

Chance: small populations will become monomorphic

A

Coalescence

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32
Q

Not all individuals have as many offspring

A

Coalescence

33
Q

time to coalescence

A

2N

-N is population size in generations

34
Q

Cannibalistic bugs – only 1 survives when they meet
When there are a lot, they run into each other a lot
When few, it is less likely

A

Bugs in a Box ex of coalescence

35
Q

will quickly coalesce to beneficial mutation

A

positive selection

36
Q

no coalescence

A

balancing selection

37
Q

neutral drift

A

arises and slowly replaces the ancestral allele by drift

38
Q

Multiregional Hypothesis

Multiple origins from H. erectus-like ancestor

A

Coalescence and Human Origins

39
Q

Out of Africa – single origin of anatomically modern humans

A

Coalescence and Human Origins

40
Q

Equal variation within populations

Africa, Europe, and Asia would all be monophyletic

A

Mutiregional

41
Q

Greater variation in Africa

African populations non-monophyletic, some closer to Europe+Asia

A

Out of Africa- supported

  • African lineages
  • sequential sister taxa to rest of world
  • African lineages with far -more genetic diversity
  • Little divergence in rest of humans
42
Q

Used coalescence to find

A

mitochondrial Eve

43
Q

mitochondrial Eve

A

Ancestor of all human mitochondria

Estimates are about 156,000-250,000 YA

44
Q
  • This ancestor existed prior to the divergence of modern populations
  • Values much more recent than if human populations descended separately from archaic Homo sapiens
A

Mitochondrial Eve

45
Q
  • Support out of Africa Hypothesis

- Variation and mutation rates leads to effective breeding population of 4,600-11,200 people

A

Mitochondrial Eve

46
Q
  • Must have been a fairly cohesive group in Africa

- Could not have been spread around because too few of them to form cohesive species if also in Europe and Asia

A

Mitochondrial Eve

47
Q

-Brief period of small population size
-Only some make it through
Reduce variation

A

Population bottlenecks

48
Q

No variation in 62 enzyme-coding loci
Unusually high homozygosity for a natural population
More than in Southern Elephant seal
30,000 individuals now
But 20 in the 1890’s
And even lower effective size because only 20% of males reproduce

A

example of population bottlenecks

-museum samples from before the bottleneck had greater variation

49
Q

Change in allele frequencies as a result of the small number of individuals that colonize a region

A

Founder effect

50
Q

Retreating glaciers created habitat

Spruce that colonized new habitat from… what?

A

leading edge

51
Q
  • nuclear DNA
  • mitochondrial DNA
  • Dispersed by wind, but not far
A

seeds

52
Q
  • nuclear DNA

- Long distance dispersal by wind

A

pollen

53
Q

Gamache et al. did 1000k N-S transect

A

Leading Edge Founder Effect

54
Q

Mitochondrial – 1 haplotype in N

A

Leading Edge Founder Effect

55
Q

Nuclear same types as in S

A

Leading Edge Founder Effect

56
Q

High between population variability throughout N for mitochondria

A

Leading Edge Founder Effect

57
Q

Hallmark of drift

A

Leading Edge Founder Effect

58
Q

Nuclear not variable between sites

A

Leading Edge Founder Effect

59
Q

believed Slightly beneficial allele with fitness of 1+s arises in large population

A

Haldane

60
Q

Fixation probability determined to be

A

2s

61
Q

population large, effects strong

A

selection dominates

62
Q

selection week, population small

A

drift dominates

63
Q

for initial mutation, population ________

A

drops out

64
Q

s>1/2Ne

A

drift

65
Q

s<1/2Ne

A

selection

66
Q

PA with highest fitness

A

Overdominance

67
Q

introduced a tremendous amount of variation

A

cross-breeding

68
Q

drift only important in _____ generation

A

first

69
Q

_____ not different in large vs. small treatments as a whole

A

%P

70
Q

variation was greater in the

A

small population

71
Q

led to discovery of differences of amino acid sequence without phenotypic differences

A

electrophoresis

72
Q

Too much variation to explain by NS

A

Neutral theory of molecular evolution

73
Q

are neutral, not mutations

A

substitutions

74
Q

generally are deleterious and are purged from the genome by NS

A

mutations

75
Q

More closely related things had fewer differences

A

AA clock

76
Q

all members of clade should be equally distant from outgroup

A

Genetic equidistance

-So a bird, a lizard, a human, and a frog should have the same number of differences from a fish

77
Q

Multiple hits at same site – more likely with time

  • More likely at 3rd position
  • By applying what is known, we get a halfway decent clock
A

Saturation

78
Q

Appears to not have an effect

Molecular clock and fossil divergence dates the same in mammals

A

Generation time

Evolution (15 decks)

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