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Evolution > EXAM 3 > Flashcards

EXAM 3 Flashcards

1
Q

2 examples of selection

A

Stabilizing and Disruptive

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2
Q

Selects against less adapted individuals at both tails of the distribution

A

Stabilizing selection

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3
Q

Before and after stabilizing selection

A

Before: broad range of variation in the population
After: for some generations later the distribution narrows but has about the same mean as before

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4
Q

______ is often observed in nature due to trade offs

A

Stabilizing selection

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5
Q

Ex of stabilizing selection (gall fly)

A

Gall size in gall fly

Large galls attract birds

Small size attracts parasitoids (Stronger agent of selection)

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6
Q

Ex of stabilizing selection (human)

A

Human birth weight

Infants with birth weights <5 or >9, had lower chance of surviving in the first month of life

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7
Q

What has influenced the selection of birth weights in humans

A

Medical intervention has decreased selection pressure by increasing survival rates of extreme birth weights

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8
Q

Selection occurs against less adapted individuals at middle of distribution; result produces > or equal to 2 character states (morphes)

A

Disruptive selection

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9
Q

Before and after disruptive selection:

A

Before: a broad range of variation exists in population
After: for generations later, individuals at both extremes of phenotypic ranges are favored over intermediate phenotypes

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10
Q

Disruptive selection is

A

antagonistic

bimodal

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11
Q

Ex of disruptive selection (seedcrackers)

A

Bill size in seedcrackers

black bellied seedcracker has 2 distinct beak sizes, large and small adapted to two different seed sizes

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12
Q

Phenomenon of disruptive selection sometimes called:

A

multiple niche polymorphism

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13
Q

Ex of disruptive selection (butterflies)

A

Mimicry complexes in butterflies

African mocker swallowtail butterfly avoids predators by mimicking poisonous ones

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14
Q

Person responsible for researching bill size in seed crackers

A

Smith

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15
Q

________ changes gene (allele) frequencies in populations

A

Natural selection

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16
Q

Why do organisms never achieve “perfect fits” to their environments

A

Nat sel. acts on genotypes that are already present (best of the worst)

Envt is ever changing

Organisms constantly make tradeoffs

Any adaptation has structural/physiological limits

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17
Q

Tracking allele frequencies through time

A

Evolution’s Null Model

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18
Q

stable populations

A

Populations that show no phenotypic change over many generations

EX: horses, sharks

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19
Q

Stability over time described mathematically by

A

Hardy-weinberg theory

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20
Q

Hardy-weinberg explains

A

genetic equilibrium of a large sexually reproducing population

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21
Q

H-W: ___________ frequencies of a population will __________ from one generation to the next, unless ________________________

A

Allele and genotype

remain constant

they are acted on by outside forces

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22
Q

Conditions required for Hardy-Weinberg Equilibrium

A 
Large population 
Random mating
No migration (no gene flow)
No selection pressure
No mutation
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23
Q

H-W equations

A

P2 + 2PQ + Q2 = 1

P + Q = 1

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24
Q

Significance of H-W

A

HW denied Genophagy: dominant alleles must, over time, eliminate recessive alleles

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25
Q

Most famous case of evolution by natural selection

A

Industrial melanism in peppered moths

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26
Q

Why did the allele freq. change in moths

A

Burning of coal produced soot that killed lichens blackening tree trunks, making typical moths more conspicuous

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27
Q

How allele freq. changed in moths

A

frequency of moths with melanic allele ↑ as air pollution ↑, while moths with gray typical allele ↓

coal burning ↓ dramatically and trees slowly lost their coatings of soot

Frequency of melanic moths ↓ from about 100% to about 0%

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28
Q

Agent of selection in peppered moths

A

Birds

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29
Q

publication bias

A

Evidence for selection more often reported than no evidence for selection

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30
Q

many studies of loci in natural populations reveal

A

Strength of selection varies greatly, from low to very high

Selection on survival and reproduction traits can be very strong

Selection strength also depends on heritability (h²)

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31
Q

reproduction traits

A

fecundity, fertility, sexual selection

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32
Q

natural selection is a _________ in evolution

A

powerful force

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33
Q

components of fitness of individual genotypes- the basis of natural selection

A

Life history traits

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34
Q

Life history traits:

A

Species vary greatly in life span

Species vary greatly in fecundity

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35
Q

EX of variety in life span

A

Ex: Bristlecone pines are among the oldest known individual organisms

Asexually propagating corals may not age and persist for thousands of years

Some rotifers live for only a few weeks

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36
Q

EX of variety in fecundity

A

Spawning oysters release clouds of minuscule eggs and sperm

Coconut is single large seed, coconut palms produce only a few at a time

X-ray of kiwi bird shows its single large egg (can only have one egg at a time)

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37
Q

Trade offs in life history traits

A

Genetic correlations occur between survival (or growth) and fecundity (reproduction)

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38
Q

Evidence of the cost of reproduction

A

female Anolis lizards

OVX lizards grew larger and lived longer than ovary producing lizards

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39
Q

_______ prevent organisms from evolving indefinitely long life spans and infinite fecundity

A

Trade offs

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40
Q

ESS

A

Evolution Stable Strategy

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41
Q

Creator of ESS

A

JM Smith

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42
Q

a strategy which, if adopted by a population in a given environment, becomes fixed

A

ESS

natural selection alone is sufficient to prevent an alternative (mutant) strategy

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43
Q

ESS refined from:

A

Nash equilibrium

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44
Q

EX of Evolution stable strategy

A

ritualized aggression in E. African oryx

Subordinate male responds to dominant male by lowering his head

If dominant male increases threat by rotating horns forward, subordinate lays back horns, leaving him defenseless against attack.

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45
Q

Deceptive signals in ESS

A

claw signaling behavior in male fiddler crabs

Large regenerated claw is an effective bluff, but has less muscle and is weaker than original claw

deters opponents and is effective at mating

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46
Q

In most organisms, reproduction occurs multiple times over their lifetimes

A

Iteroparity

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47
Q

In other organisms, reproduction occurs once, after many years and then death

A

Semelparity (or masting)

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48
Q

Delayed onset of reproduction most likely evolved in

A

species with high rates of adult survivorship

Ex: In some snakes and lizards, the lower the annual mortality rate of adults, the later they reach reproductive maturity

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49
Q

EX of semelparity: ______ engage in highly synchronous reproduction and then die

A

Bamboos

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50
Q

Advantageous if reproduction is so stressful (or risky) that an individual is unlikely to reproduce more than once

A

Big bang reproduction seen in Coho salmon

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51
Q

___________________ are extremely variable among different animals

A

Parental Care and Mating systems

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52
Q

In most animals, one or both sexes may mate with multiple partners

A

promiscuous mating

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53
Q

In many ____ and _____, females provide care, but males do not and may mate with multiple partners

A

birds
mammals
polygyny

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54
Q

In some _____, ____, and ______, females may mate and lay eggs with different males

A

fish
frogs
new birds
polyandry

EX: males guard eggs and care for offspring
EX: male seahorses give birth

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55
Q

In many ____, some _____ and ____, males and females form pair bond and contribute biparental care of offspring

A

birds
mammals
insects
monogamy

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56
Q

Females may also increase their reproductive success by laying eggs in nests of unwitting foster parents

A

brood parasites

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57
Q

mochokid catfish

A

mouth brooder

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58
Q

Cuckoos and cowbirds

A

Brood parasites

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59
Q

At old age, selection for reproduction and survival is weak, but the timing of reproduction and death can evolve

A

Senescence

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60
Q

Two evolutionary theories of senescence

A

Antagonistic pleiotropy

Mutation accumulation

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61
Q

alleles that increase allocation in reproduction early in life will decrease function later in life

A

Antagonistic pleiotropy:

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62
Q

random mutations accumulate later in life and cannot be selected against

A

Mutation accumulation:

63
Q

Drosophila populations selected for higher fecundity later in life show their egg production is lower, as predicted

A

Ex of Antagonistic pleiotropy

64
Q

In Drosophila, genetic variance for reproductive success increases for older than younger age classes, as predicted

In birds and mammals, mating between relatives results in increase in inbreeding depression at later than earlier ages

A

Ex of Mutation accumulation

65
Q

In ______________________, sex determines solely by _______

A

humans, other mammals and insects

genetics

66
Q

Sex determination in humans, other mammals and insects

A 
Females = XX
Males = XY
67
Q

In ______ and lepidoptera (_______), sex chromosomes are ________

A

birds

moths and butterflies

reversed

Females = WZ
Males = ZZ
68
Q

In other groups, sex determined partly by ______ or ___________

A

physical

social environment

Ex: in reptiles
cool temps = males
Warm temps = females

69
Q

Still other animal exhibit _________

A

hermaphroditism

70
Q

All hymenoptera (_____________) exhibit ________

A

ants, bees, wasps, scale insects, and many mites

haplodiploidy

71
Q

Accumulation of _______ is faster in sexual than asexual populations

A

beneficial mutations

72
Q

For sexual species strength of ______ on new mutations is markedly _____ due to _______

A

natural selection
↑
recombination effects

73
Q

Ex of hermaphrodism

A

leopard slug

74
Q

All start as males but then switch to female

A

clownfishes

75
Q

Some _____ have flowers that do not open

A

cacti

Reproduce almost entirely by self fertilization

76
Q

Use conjugation and other mechanisms to exchange genetic material

A

Bacteria like E. coli

77
Q

Many animals include ____________ to attract and court mates

A

sex pheromones

Commonly released by females; detected by males through antennae

78
Q

male orchid bees of tropical america

A

Collect a scent from certain flowers and use it as their sex pheromone

79
Q

Exploitation of pheromones in Agriculture

A

Pheromone traps are used in apple orchards to manage codling moths

For orchards >5 acres, a minimum of 5 traps is recommended

80
Q

Condition where 2 sexes exhibit different traits beyond differences in their sexual organs

A

Sexual dimorphism

81
Q

EX of Sexual dimorphism

A

anglerfishes

When a male finds a female, he bites and attaches himself to her permanently

His body fuses with hers and his organs degenerate except for testes

More than one male can attach

82
Q

When one individuals behavior benefits another it is _______

A

cooperative

Mutualism, altruism

83
Q

If both individuals are harmed behavior is

A

Spiteful

84
Q

If only recipient is harmed and actor is benefited behavior is

A

Selfish

85
Q

If both individuals are benefited behavior is

A

Mutualistic

86
Q

If recipient is benefited and actor is harmed behavior is

A

Altruistic

87
Q

The ______ and ______ each individual gets from _______ is measured as ______ (i.e., contribution of genes to future generations)

A

advantage
disadvantage
cooperation
fitness

88
Q

Inclusive fitness:

A

direct fitness + indirect fitness

89
Q

direct fitness

A

effect on fitness of individual beating it

90
Q

indirect fitness

A

fitness of other individuals that carry same alleles

91
Q

Fitness

A

contribution of genes to future generations

92
Q

Biological differences between species prevent successful breeding, leading to ____________

A

isolation mechanisms

93
Q

Ex of isolation mechanisms

A

Almost all reproductive isolation in monkeyflowers caused by elevational separation & pollination isolation

94
Q

2 types of barriers

A

pre zygotic and post zygotic

95
Q

Pre zygotic barriers

A

traits that impede gamete transfer to other species

96
Q

Factors influencing prezygotic barriers

A

Habitat isolation
Temporal isolation
Behavioral isolation
Post mating barriers

97
Q

Habitat isolation:

A

spatially separated species

98
Q

Temporal isolation

A

populations breed at different seasons or times of day

99
Q

Behavioral isolation

A

species-specific calls, rituals, postures

100
Q

EX of behavioral isolation in Lace WIngs

A

Lacewings that all belong to the same genus, but different species, have different sound waves of their songs. So they each only attract specific males

101
Q

Postmating barriers

A

mating occurs, but gametes don’t transfer, and zygotes don’t form.

102
Q

Factors influencing post mating barriers

A

Mechanical isolation

Gamete isolation

103
Q

Mechanical isolation

A

Failure of mechanical fit of reproductive structures

104
Q

Gamete isolation

A

Failure of proper transfer of gametes or fertilization

105
Q

EX of mechanical isolation

A

genital arch in male Drosophila involved in transferring sperm to females

106
Q

EX of Gamete isolation in abalones

A

among abalones, sperm only enters if protein lysin (from sperm) can dissolve egg membrane

107
Q

Postzygotic barriers

A

Lower survival or reproductive rates of hybrid zygotes

108
Q

Hybrid sterility often limited to heterogametic

A

Haldanes rule

109
Q

EX of post zygotic barriers

A

chromosomes of zebra and donkey parents differ in number and structure

both male ligers and tigrons are sterile, but female of both species can successfully breed with tigers and lions

110
Q

Genetic distances among species measured by

A

degree of difference (D) in allozyme allele

111
Q

summarized 60 years of experiments on Drosophila

A

Coyne and Orr

112
Q

Findings of Coyne and Orr:

_______ of prezygotic and postzygotic isolation were ___________ with time since populations were separated

A

Strength

increased gradually

113
Q

Reinforcement

A

When there is stronger prezygotic isolation due to selection against low fitness

114
Q

Findings of Coyne and Orr:

Prezygotic isolation measured by observing

A

mating (vs failure to mate) between flies from different populations in lab

115
Q

Findings of Coyne and Orr:

Postzygotic isolation: based on

A

survival and fertility of hybrid individuals in lab

116
Q

_______ is a stronger barrier to gene exchange than __________

A

Prezygotic isolation

postzygotic isolation

117
Q

______ is stronger among _______ than among _______ pairs of taxa

A

Prezygotic isolation
sympatric
allopatric

118
Q

Process by which new species form through reproductive isolation

A

Speciation

119
Q

2 basic types of speciation

A

Splitting: two populations evolve differences until they eventually become separate species (first pic)

Budding: subpopulation “buds off” from main population and evolves; forms new species leaving most of larger population unchanged (2nd picture of arrows)

120
Q

Two populations evolve differences until they eventually become separate species (first pic)

A

Splitting

121
Q

subpopulation “buds off” from main population and evolves; forms new species leaving most of larger population unchanged (2nd picture of arrows)

A

Budding

122
Q

__________ isolate species and prevent interbreeding

A

Geographical barriers

123
Q

EX of Geographical barriers

A

mountains, rivers, and oceans

124
Q

in two antelope squirrel species live on opposite sides of the Grand Canyon

Separation is both ______ and______

A

geographical

ecological

125
Q

studied dusky salamanders from southern appalachian mountains in the Eastern US

A

Tilley

126
Q

Dusky salmanders and fresh water fish experiments are evidence for

A

Allopatric speciation

127
Q

Salamander experiment:

A

Brought males and females from different and same populations together and scored proportion of pairs that mated (mating experiments)

More geographically distant populations were more genetically different and were less likely to mate (picture of salamanders on graph)

128
Q

studied 6 freshwater fish species from coastal plains of SE US

A

Avise

129
Q

Avise’s study on 6 spp of freshwater fish

A

Form 2 distinct clades in E and W Florida

Implies minimal gene flow between E and W

Genetic divergence occurred 3-4 MYA

130
Q

Reproductive isolation occurs first within population

A

Sympatric speciation

131
Q

Allopatric speciation is driven by

A

Geographic isolation

132
Q

some insect species programmed to lay eggs on host plants they were born on, leading to development of new species via _______

A

EX of sympatric speciation

Disruptive selection

133
Q

“Host races” of apple maggot fly from hawthorn and apple hosts

A

Ex of Sympatric speciation

Hawthorns are ancestral host of fly

fly started to infest apple trees in same areas as normal host (now known as apple maggot)

Gene flow reduced to 2% between hosts

Three weeks separate emergence/mating time on apple and hawthorn (temporal isolation)

134
Q

In sympatric speciation

A

Necessary conditions are more limited than in allopatric speciation

135
Q

Sympatric speciation:

Many herbivorous insects mate on the plants they feed which ensures

A

mating will occur between individuals with same host preference

136
Q

EX of sympatric speciation:

Sister spp. of palms on Lord Howe island

A

Island is small and remote, lying between Aus and NZ

Two palms are kentia palm and curly palm

Grow in close proximity and wind pollinated

Key driver is 6 wk difference in peak flowering times

reproductive isolation is based on separation by different flowering seasons

137
Q

Sympatric Speciation caused by Chromosomal Abnormalities

A

Autopolyplpoidy

Allopolyploidy

138
Q

Auto and allopolyploidy

A

Become instant species through reproductive isolation form parent population

May also hybridize with closely related spp. with same chromosome number

139
Q

Common cause for emergence of plant species

A

polyploidy

140
Q

_____ of flowering plant spp may have originated as polyploids

A

~80%

141
Q

BSI

A

Biological speciation interval

142
Q

Biological speciation interval

A

mean time that has elapsed between 2 sequential forks in a phylogeny

143
Q

How is BSI estimated:

A

from time between present number of species and common ancestor of clade

144
Q

BSI for cichlid fishes

A

≤ 0.3 MY

145
Q

BSI for horses

A

3 MY

146
Q

BSI for bivalve mollusks

A

6-11 MY

147
Q

TFS

A

Time for speciation

148
Q

TFS determined using

A

Sequence divergence of mitochondrial DNA:

149
Q

As a rule, TFS is ______ for ______ than speciation involving _______

A

shorter

polyploids

mutation or drift

150
Q

Two studies agree that some NA songbirds diverged since ________ began

A

Pleistocene epoch

151
Q

Frogs take ______, on average to complete speciation

A

1.5 MY

152
Q

Models of sympatric speciation postulate the existence of

A

Disruptive selection based on resource usage

153
Q

two antelope squirrel species live on opposite sides of the Grand Canyon ex of

A

Allopatric speciation via vicariance

Evolution (4 decks)

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