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Evolution > Test 2 > Flashcards

Test 2 Flashcards

1
Q

Population genetics

A

Study of the distribution of alleles in populations and causes of allele frequency changes

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2
Q

Allele frequency

A
  • The proportion of all copies of a gene that is made up of a particular gene variant (allele)
  • the number of copies of a particular allele divided by the number of copies of all alleles at the locus in a population
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3
Q

In population genetics, allele frequencies are used to depict..

A

The amount of genetic diversity at the individual, population, and species level

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4
Q

Who developed an equation for population genetics?

A

Hardy and Weinburg

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5
Q

Hardy-Weinburg equilibrium

Population allele frequencies do not change if:

A
  • population is infinitely large
  • geneotypes do not differ in fitness
  • there is no mutation
  • mating is random
  • there is no migration
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6
Q

Through mathematical modeling based on probability, they concluded that..

A

Gene pool frequencies are inherently stable but that evolution should be expected in all populations virtually all of the time

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7
Q

Hardy-Weinburg theorem proves that allele frequencies do not change in the absence of..

A

Drift, selection, mutation, and migration

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8
Q

Mechanisms of ___ are forces that change allele frequencies

A

Evolution

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9
Q

___ frequencies predict ___ frequencies

A

Allele, genotype

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10
Q

Predictions from Hardy-Weinburg

A

p^2 + 2pq + q^2
p - frequency of dominant allele
q - frequency of recessive allele

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11
Q

1 in 1700 U.S. Caucasian newborns have ___

A

Cystic fibrosis

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12
Q

Genetic drift

A
  • along with natural selection, mutation, and migration - is one of the basic mechanisms of evolution
  • simply the evolutionary equivalent of a sampling error
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13
Q

Hardy-Weinburg serves as the fundamental ___ in population genetics

A

Null model

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14
Q

Drift reduces ___ in a population

A

Genetic variation

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15
Q

Alleles are lost at a faster rate in ___ populations

A

Small

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16
Q

Bottlenecks ___ genetic variation

A

Reduce

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17
Q

A bottleneck ___ genetic drift

A

Causes

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18
Q

Population bottlenecks occur when..

A

A populations size is reduced for at least one generation

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19
Q

Founder effect

A

Occurs when a new colony is started by a few members of the original population

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20
Q

Both drift and founder effect result from __

A

Random sampling

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21
Q

Fitness

A

Reproductive success of an individual with a particular phenotype

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22
Q

Components of fitness

A
  • survival to reproductive age
  • mating success
  • fecundity
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23
Q

Relative fitness

A

Fitness of a genotype standardized by comparison to other genotypes

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24
Q

Natural selection is more powerful in ___ populations

A

Large

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25
Q

___ weaker in large populations

A

Drift

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26
Q

Alleles that lower fitness experience ___ selection

A

Negative

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27
Q

Alleles that increase fitness experience ___ selection

A

Positive

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28
Q

Additive

A

Allele yields twice the phenotypic effect when two copies present

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29
Q

Dominance

A

Dominant allele masks presence of recessive in heterozygote

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30
Q

Estimate of new mutations each generation in humans

A

9.8 billion

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31
Q

Frequency-dependent selection

A

An evolutionary process where the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population

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32
Q

In positive (diversifying) frequency-dependent selection,

A

The fitness of a phenotype increases as it becomes more common

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33
Q

In negative (purifying) frequency-dependent selection,

A

The fitness of a phenotype increases as it becomes rarer

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34
Q

Inbreeding coefficient

A

Probability that two alleles are identical by descent

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35
Q

Polygenic trait

A

Influenced by many genetic loci

  • interaction between alleles (epistasis)
  • interaction with environment (phenotypic plasticity)
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36
Q

Quantitative genetics

A

Study of the genetic mechanisms of continuous phenotypic traits

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37
Q

Epistasis

A

Phenomenon in which the expression of one gene depends on the presence of one or more “modifier genes”

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38
Q

A gene whose phenotype is expressed is called ___.

A

Epistatic

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39
Q

A gene whose phenotype is altered or suppressed is called ___.

A

Hypostatic

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40
Q

Phenotypic plasticity

A

Ability of an organism to change its phenotype in response to changes in the environment

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41
Q

Phenomenon in Daphnia, known today as cyclomorphosis

A

When exposed to the presence of a predator they respond by altering the shape of their body to produce a “helmet”

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42
Q

Heritability

A

Proportion of phenotypic variance due to genetic differences

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43
Q

Broad sense of heritability includes:

A
  • additive effects
  • dominance effects
  • epistatic effects
  • maternal/paternal environmental effects
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44
Q

Natural selection

A

Only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated

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45
Q

Natural selection will operate on anything that has the following properties:

A
  • reproduction
  • inheritance
  • variation in fitness
  • variation in individual characteristics
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46
Q

Directional selection

A

Favors those individuals who have extreme variations in traits within a population
- greyhound dog bred to run faster

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47
Q

Stabilizing selection

A

Favors the norm, the common, average traits in a population

- husky needs to be perfectly medium - too big will sink in snow, too small would not be strong enough

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48
Q

Disruptive selection

A

Favors extremes as well
Sudden changes in the environment creates a sudden force favoring that extreme
- changes in the environment when a meteor crashed into earth

49
Q

How much the population changes depends on:

A
  • Selection differential (S)

- Heritability

50
Q

Selection coefficient

A
  • Measure of the relative fitness of a phenotype
  • s = 0 then is selectively neutral compared to the favored phenotypes
  • s = 1 indicated complete lethality
51
Q

Selection can occur without ___

A

Evolution

52
Q

Quantitative trait loci (QTLs)

A

Stretches of DNA containing or linked to the genes that underlie a quantitative trait

53
Q

Mapping regions of the genome that contain genes involved in specifying a quantitative trait is done using what?

A

Molecular tags, commonly SNPs

54
Q

Quantitative traits

A

Phenotypes that vary in degree and can be attributed to polygenic effects
- color of coat in mice

55
Q

Rapid change can lead to mismatch between ___ and ___.

A

Plastic traits and environment

56
Q

The biological sciences now generally define ___ as being the sum total of the genetically inherited changes in the individuals who are the members of a populations gene pool.

A

Evolution

57
Q

Diversity in darwins finches

A

Beak size

58
Q

Variation in beak size influences what?

A

Efficiency at eating different types of seeds

59
Q

Drought resulted in more __, __ seeds and favored _ beaked birds.

A

Hard, woody, larger

60
Q

Light coat color evolved ___ in different populations

A

Independently

61
Q

Evolution in response to natural selection is inevitable if:

A
  • there is variation in a trait
  • variation is heritable
  • some variants reproduce more than others
62
Q

___ can bring alleles to new locations

A

Gene flow

63
Q

Aposematism favored only in areas where ___ co-occur

A

Coral snakes

64
Q

Natural selection can lead variation over the ___ range of a species

A

Geographic

65
Q

___ selection occurs when agents of selection act in opposing directions

A

Stabilizing

66
Q

Gall flies

A

Stabilizing selection on gall size

67
Q

Ability to digest lactose correlated with what?

A

Domestication of cattle

68
Q

Domestic dog diversity created in last ___ years

A

15,000

69
Q

Pesticides and herbicides act as agents of ___

A

Selection

70
Q

Creation of refuges can slow the evolution of ___

A

Resistance

71
Q

Introduced cane toads have led to evolution of ___ populations.

A

Black snake

72
Q

Evolution of shorter male horns due to ___.

A

Hunting

73
Q

The speed of evolution depends on amount of ___ and ___.

A

Amount of genetic variation and strength of selection

74
Q

Sex creates new ___

A

Genotypes

75
Q

Disadvantages of sexual reproduction

A
  • twofold cost of sex
  • search cost
  • reduced relatedness
  • risk of stds
76
Q

Advantages of sexual reproduction

A
  • combining beneficial mutations
  • generation of novel genotypes
  • faster evolution
  • clearance of deleterious mutations
77
Q

In the contest to explain sex, only ___ hypotheses remained in contention

A

Two

78
Q

The deleterious mutation hypothesis

A

Sex exists to purge a species of damaging genetic mutations

- Kondrashov

79
Q

In an asexual population, every time a creature sides because of a mutation,

A

The mutation dies with it

80
Q

If the ones with lots of mutations die, then

A

Sex purges the species of mutations

81
Q

Why eliminate mutations this way, rather than correcting more of them by better proofreading?

A

It may be cheaper to allow some mistakes through and remove them later

82
Q

The rate of deleterious mutations must exceed ___ per individual per generation is sex is to earn its keep eliminating them

A

One

83
Q

Red queen hypothesis

A
  • Valen
  • it takes all the running you can do, to keep in the same place
  • hosts and disease, predator and prey
  • sex is needed to fight disease
  • advantages of sex and constant coevolutionary arms races
84
Q

Heterozygosity and polymorphism are lost when…

A

A lineage becomes inbred

85
Q

Hamilton built a..

A

Computer model of sex and disease

86
Q

Some species can reproduce both sexually and asexually

A

Strawberry plants
Sponges
Water fleas

87
Q

Sex creates new genetic variation by..

A

Mixing parental alleles

88
Q

Ecological situations that require rapid evolution are likely to favor __

A

Sex

89
Q

Asexual lineages have evolved mechanisms that compensate for ..

A

Lack of sex

90
Q

___ results in differential investment in reproduction

A

Anisogamy

91
Q

Anisogamy

A

Form of sexual reproduction involving the union or fusion of two dissimilar gametes

92
Q

Limitations of reproductive success differ for the sexes

A

Females are limited by fecundity

Males are limited by the number of mates they can obtain

93
Q

Investment differences can extend past ___

A

Fertilization

94
Q

Uncertain paternity may explain why..

A

Male parental care is rare

95
Q

Asymmetrical parental care alters what?

A

Operational sex ratio

96
Q

Operational sex ratio

A

Ratio of males to females capable of reproducing at a given time

97
Q

Ornaments

A

Attractive traits that increase mating success

98
Q

Armaments

A

Weaponry used to outcompete other individuals

99
Q

Selection is a two-way street

A

Male competition

female choice

100
Q

Benefits of female choice

A
  • direct benefits

- indirect benefits

101
Q

Direct benefits

A

Benefit the female directly

Food, nest sites, protection

102
Q

Indirect benefits

A

Benefits that affect the genetic quality of the females offspring

103
Q

Males may compete for __

A

Territory

104
Q

Competing for mates is __

A

Costly

105
Q

Females may benefit from ___

A

Cannibalism

106
Q

Voluntary ___ in redback spiders

A

Self-sacrifice

107
Q

Female preferences are often ___

A

Consistent

108
Q

Female preferences may arise from..

A

Preexisting sensory bias

109
Q

Monogamy

A

One male pairs with one female

110
Q

Sexual monogamy

A

Partners mate with each other exclusively

111
Q

Social monogamy

A

Partner pair but may cheat

112
Q

Polygyny

A

Males mate with multiple females

113
Q

Polyandry

A

Females mate with multiple males

114
Q

Development of weapons can involve what?

A

Trade-offs

115
Q

Ornaments can serve as what?

A

Handicaps

116
Q

___ selects for male traits that increase paternity

A

Polyandry

117
Q

Sperm competition drives evolution for what?

A

Larger testes

118
Q

Sexual conflict results in what?

A

Antagonistic coevolution

119
Q

Sexual conflict

A

Traits that confer a fitness benefit on one sex but cost to the other

Evolution (7 decks)

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