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Evolution > 4th weekly quiz > Flashcards

4th weekly quiz Flashcards

1
Q

what are the steps to test for adaptation

A

observation
experiments
comparisons

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2
Q

what does a null hypothesis assume

A

there is no relationship between the 2 variables being tested

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3
Q

what is the comparative method

A

comparisons across species to test predictions

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4
Q

what is the issue with using stats with evolution

A

species are not independent data points

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5
Q

what is a type 1 error

A

false positive

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6
Q

type 2 error

A

fasle negative

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7
Q

what is the main method of the comparative method

A

phylogenetically independent contrasts (PICs)

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8
Q

what is biological scaling (allometry)

A

the change in organisms in relation to change in body size

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9
Q

what do independent contrasts summarize

A

summarize the amount of character change across each node in the tree

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10
Q

what can independent contrasts be used to estimate

A

rate of change across a phylogeny

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11
Q

why might adaptation be absent

A

genetic constraints
physical constraints
phyletic contraints
trade offs

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12
Q

what are the genetic constraints on adaptation

A

even if selection should select in favour of the hypothetical trait, it can’t

inertia

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13
Q

what is inertia in evolution

A

limitations on future evolutionary pathways that have been imposed by previous adaptations

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14
Q

what are physical constraints on evolution

A

when like certain traits must be there to function (?)

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15
Q

what is a phyletic constraints

A

historical restrictions based on the evolutionary history of the species

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16
Q

what are the trade off constraints on adaptation

A

trade off between allocation of energy towards growth vs reproduction

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17
Q

what is multi-level selection

A

how certain traits can increase fitness at one level and decrease fitness at another level

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18
Q

what is the main function of sex

A

to allow alleles at one locus to float freely to another locus from generation to generation

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19
Q

why is sex a costly behaviour

A
  • complicated (finding a mate)
  • costly (lots of courting and competition)
  • dangerous (risk of predation and disease)
  • recombination scrambles genotypes (bad if genotype is already in a favourable combination)
  • delays reproduction (takes longer)
  • genome dilution (females on contribute 1/2 their genetic material)
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20
Q

what is syngamy

A

fusion of egg and sperm

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21
Q

what is the two-fold costs of sex

A

less reproduction

parthenogenetic females theoretically have more offspring than sexual females

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22
Q

how does hardy Weinberg genetics and the genetics of selection treat each locus?
what is issue with it?

A

as independent

alleles are linked in chromosome

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23
Q

what is a haplotype

A

a group of genes within an organism that are inherited together from a single parent

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24
Q

what is linkage disequilibrium

A

the non random association of alleles at different loci in a gene population

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25
Q

what does sex do to linkage disequilibrium

A

sex breaks linkage disequilibrium down

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26
Q

what is linkage equilibrium

A

when haplotype frequencies in a population have the same value they would if the genes at each locus were combined at random

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27
Q

what is linkage disequilibrium caused by

A

often by alleles being physically linked (though not necessarily)

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28
Q

do processes that affect allele frequencies (drift, selection) affect other loci

A

yes

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29
Q

what are the key features of sex

A

can combine beneficial mutations on same chromosome

reduce linkage disequilibrium

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30
Q

how are recombination rates effected as distance between loci increase

A

increase

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31
Q

how linkage disequilibrium react as loci become farther apart

A

decrease

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32
Q

what is clonal interference

A

the competition between lineages arising from different beneficial mutations in an asexually reproducing population

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33
Q

what does recombination tend to do to genotypes in relation to other genotypes

A

randomize the genotype

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34
Q

what creates linkage disequilibrium

A

genetic drift
selection on more than one trait at a time
sampling two populations with different compositions
creation of new mutations

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35
Q

how does drift effect linkage disequilibrium

A

can both create it and reduce it

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36
Q

how does linkage disequilibrium effect rate of change of populations

A

can slow it

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37
Q

how can linkage disequilibrium slow evolution in populations

A

if beneficial mutations happen near “bad” mutations since selection acts on phenotypes so the sum of selection coefficients

strong selection at a loci can drag along alleles on the same loci

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38
Q

what is evidence of a strong linkage disequilibrium in a well mixed population (where HWE should hold) evidence of

A

recent natural selection

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39
Q

what is sex

A

bringing haplotypes together for recombination

40
Q

how does sex speed up evolution

A

breaks up genotypes

41
Q

what are some alternatives to sex

A

vegetative (asexual) propagation
parthenogenesis
gynogenesis and hybridgenesis

42
Q

what is vegetative (asexual) propagation

A

development of offspring from part of an adult body

43
Q

what is parthenogenesis

A

meiosis suppressed development of offspring from unreduced egg in female

44
Q

what is gynogeneisis and hydidogenesis

A

meiosis is suppressed

development of offspring from faux fertilized egg

45
Q

what sex are the offspring resulting from gynogeneisis and hybridogenesis

A

all female

46
Q

what are all asexual vertebrates the result of

A

hybridization of 2+ other species

47
Q

why do asexual species go extinct more often

A

can’t adapt fast enough

they actively deteriorate

48
Q

what is muller’s rachet

A

process through which, absence of recombination, an accumulation of irreversible deleterious results

49
Q

what is genetic load

A

presence of unfavourable genetic material in the genes of a population

50
Q

when is muller’s ratchet fastest

A

in a small populations with high mutation rates and mildly deleterious mutations

51
Q

what does sex do to muller’s ratchet

A

breaks it through recombination and outcrossing

52
Q

why is sex advantageous in the long run

A

asexuals go extinct more often

53
Q

why are asexuality immediately advantageous

A

cost of males

54
Q

what is the short term benefit of sex

A

recombination has postive s since it creates variation which is selected for in environments that vary

55
Q

what are the two main theories for short term benefits of sex

A

tangled bank

red queen

56
Q

what is the tangled bank theory

A

spatial heterogeneity in environments favour sex

  • if offspring disperse, the variation created by sex makes them more likely some will be successful in varied environments
  • if offspring dont disperse: less likely for competition between siblings
57
Q

what is the red queen theory

A

species must adapt and evolve not just. for reproductive success, but also for survival since competing organisms are evolving

58
Q

what do tangled bank and red queen both predict about when sex is favoured

A

it is favoured at high stable densities (lots of competition)

59
Q

when is asexuality most common

A

in poles and other harsh conditions

60
Q

what are asexuals often good at

A

being early colonizers of novel habitats because of rapid growth rate

61
Q

when should recombination be most common

A

when litter size is large

within-brood variation is possible

62
Q

is asexuality rare or common

A

rare

63
Q

what does long term mutation load and environmental variation favour (sexual vs asexual)

A

sexual

64
Q

how does recombination effect speed of evolution and why

A

speeds it up

by allowing for more effective selection

65
Q

does recombination allow purging of mutational load

A

yes

66
Q

what is quantitative genetics

A

study of traits affected by many genes and the environment

67
Q

what is a population

A

vague term denoting a set of demographically linked individuals

68
Q

are interactions stronger between members of the same population or different population

A

same

69
Q

what can total variation be broken down into

A 
genetic variation (Vg)
environmental variation (Ve)
genotype by environment variation (Vge)
70
Q

what is genetic variation

A

variation due different allele/genes

71
Q

what is genetic variation supplied by

A

mutations

72
Q

what is environmental variation

A

variation due to different environments

73
Q

is environmental variation heritable

A

no

74
Q

what is genotype by environment variation

A

variation due to interactions between genes and the environment

75
Q

what is a fitness function

A

relationship between trait value and relative fitness

76
Q

what is relative fitness

A

probability of contributing to next generation

77
Q

what are the different types. of fitness functions

A

directional selection
disruptive selection
stabilizing selection

78
Q

what is directional selection

A

selection for one extreme over the other extreme

79
Q

how does directional fitness affect the mean phenotype

A

causes a change in it

80
Q

what is disruptive selection

A

selection for both extremes, against moderate traits

81
Q

how does disruptive selection affect mean phenotype and distribution

A

broadens distribution but doesn’t necessarily affect mean

82
Q

what is stabilizing selection

A

selection for moderate traits, against extremes

83
Q

how does stabilizing selection affect phenotypic mean and distribution

A

narrows distribution but doesn’t necessarily change mean

84
Q

why is recombination (sex) necessary for quantitative genetics

A

recombination allows us to think of alleles as free from all genetic background and to be able to talk about their mean and additive effects

85
Q

how much of a population’s variation is due to Vg

A

50-80%

86
Q

what does Vp stand for

A

phenotypic variation

87
Q

what is Va

A

additive variation

88
Q

what is heritability

A

the proportion of variation (Vp) in a trait that is due to additive variation in genes (Va)

proportion of variation by all genetic effects (Vg)

measure of how well differences in people’s genes account for differences in their traits

89
Q

what does additive genetic variation determine

A

degree of resemblance between relatives

determines the response of a population to selection

90
Q

what does Va estimate

A

heritability of a trait in a specific single population

91
Q

what is h^2

A

= ability to predict differences in offspring based on differences in parents

92
Q

what is h^2 due to

A

only additive components of alleles underlying it

93
Q

what is mid parent value

A

parental phenotypes

94
Q

what does it mean when h=0

A

no heritability

95
Q

is heritability environment specific

A

yes

96
Q

what determines the evolution of a trait

A

heritability combined with strength of selection

97
Q

why is heritability for fitness related traits low

A

since fitness related alleles have fewer genetic variation (since selection lowers variation) = lower heritability

Evolution (8 decks)

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