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evolution > envs lecture 12 > Flashcards

envs lecture 12 Flashcards

1
Q

what is found at all levels of all biological organization

A

cooperation and conflict

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2
Q

examples of cooperation

A

seemingly altruistic behavior to gather food, raise offspring, defend resources like food/nest

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3
Q

example of conflict

A

infanticide, siblicide

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4
Q

what’s a useful way to think about social interactions among individuals

A

start w/ a table of the effects on actor and recipient

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5
Q

how are the effects on the actor and recipient classified

A

w/ respect to how they effect the fitnesses of the two individuals (increase in fitness or decrease in fitness)

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6
Q

what does mutualistic behavior do (in terms of fitness)

A

increases fitness for both actor and recipient

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7
Q

what is mutualistic behavior a form of

A

cooperation

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8
Q

what is altruistic behavior

A

negative/costly effect on actor but benefits the recipient by increasing fitness

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9
Q

what is altruistic behavior a form of

A

cooperation

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10
Q

what is selfish behavior

A

benefits actor by increasing fitness, but negative effect on recipient by decreasing fitness

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11
Q

what is selfish behavior a form of

A

conflict

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12
Q

what is spiteful behavior

A

both a negative effect on actor and recipient; fitness decreases for both of them

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13
Q

what is spiteful behavior a form of

A

conflict

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14
Q

what is cheating

A

individuals cheat when they can benefit from actions of others without providing reciprocal benefits in return

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15
Q

describe cheating vs. cooperation

A

if cheating has high fitness in population of cooperators, then mutation that causes cheating will spread and cooperation will collapse

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16
Q

so what is big question/puzzle

A

how does natural selection favor cooperative behavior when cheating is a possibility

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17
Q

give example of cheating in unicellular slime mold

A

when food is scarce, individual cells aggregate intoo a slug that can move around, slug –> mushroom like structure cells form spores that disperse while those in stalk die w/o reproducing

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18
Q

basically what happens to cells in stalk in unicellular slime mold

A

sacrifice themselves for benefit of cells that make spore

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19
Q

what gene allows slime mold cells to cheat

A

chtA mutation

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20
Q

what does chtA mutation cause

A

them to behave selfishly and avoid contributing to the stalk

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21
Q

what happens in a mix of wild-type cells and chtA cells

A

mutant cells become concentrated in cap and are more likely to form reproductive spores

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22
Q

what happened to frequency of selfish mutant allele over 11 cycles

A

frequency increase

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23
Q

what happens to cheating mutation, and what is question

A

cheating mutation doesn’t go to fixation, why don’t we see end of cooperative behavior and fixation of cheating mutation in population?

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24
Q

what did biologists think until 1960s

A

evolution favored traits for group selection (that benefited population or species)

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25
Q

but what do we know about group selection

A

group selection is uncommon

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26
Q

why is group selection uncommon

A

b/c of strong fitness advantage of cheating

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27
Q

so why hasn’t cheating mutation spread to fixation?

A

colonies that have high relatedness evolve resistance to cheaters

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28
Q

describe competition experiment w/ slime mold

A

compared evolved cheaters (non-fruiters) and both their ancestors and evolved fruiters (wild-type) which are both cooperative.

evolved fruiters are fruiters that have evolved in presence of cheaters

if nonfruiters cheat the ancestor as expected, resistance to cheating will be established. if they cheat the evolved fruiters less or not at all, shows that resistance to cheating has evolved in experiment.

if nonfruiters cheat ancestor and evolved fruiters equally, we would expect to see same number of nonfruiters in study for both mixtures

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29
Q

describe results of competition experiment

A

evolved fruiter evolves resistance to cheating before cheating sweeps thru population and multicellularity is lost

colonies are able to evolve resistance against cheating.

when colonies closely related, stronger resistance

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30
Q

what conditions can cooperation or altruism evolve

A

mutualism, reciprocity (form of mutualism), kin selection

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31
Q

what is mutualism

A

cooperation among unrelated individuals where both actor and recipient benefit

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32
Q

what is reciprocity

A

another form of mutualism; individuals reciprocally increase each other’s fitness

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33
Q

what is kin selection

A

altruism among related individuals

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34
Q

give example of cooperation among non-kin (unrelated individuals)

A

flocking behavior

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35
Q

what does flocking behavior do

A

lowers risk of predation among individuals in a group –> less likely predator will focus on individual

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36
Q

what is flocking behavior

A

selfish herd effect

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37
Q

what does selfish herd effect do

A

lowers risk of predation among individuals in groups

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38
Q

what is shared vigilance

A

groups lookout for predators together; more time can be devoted to grazing in larger herd

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39
Q

give another example of cooperation among non-kin

A

starlings flock in response to predator –> selfish herd effect

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40
Q

what is the point of selfish herd effect

A

safety in numbers

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41
Q

another example of cooperation among non-kin

A

wolves & cooperative predators (lions, hyenas) hunt cooperatively in packs to take down prey a single individual couldn’t take down

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42
Q

what does hunting large prey require

A

cooperative behavior

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43
Q

what do some systems have

A

delayed benefits

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44
Q

what are delayed benefits

A

helping at the nest where more than a pair takes care of young at a nest; sometimes helpers are kin, sometimes they aren’t

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45
Q

what do manakin leks do

A

cooperation among non-kin; delayed benefits

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46
Q

describe delayed benefits in manakin leks

A

two males court female. female goes w/ dominant males. when dominant male dies, subordinate male takes over

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47
Q

what do baboons do

A

reciprocity

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48
Q

what did robert trivers suggest

A

reciprocity; cooperation can involve when one individual provides fitness benefit to another, as long as 2nd individual returns favor

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49
Q

what is reciprocity

A

individuals provide reciprocal favors to one another that both provide fitness benefits

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50
Q

when can cooperation evolve

A

when individuals provide reciprocal favors to one another that both provide fitness benefits

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51
Q

what can favor cooperative behavior

A

repeated interaction

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52
Q

what does cooperation/reciprocity require

A

requires repeated interactions and ability to recognize individuals

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53
Q

describe reciprocity in yellow baboons

A

offspring of female yellow baboons that have strong bond w/ females other than mom have better survival

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54
Q

when can cooperation be enhanced

A

when selfish individuals are punished

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55
Q

where is reciprocity common

A

mammals, including humans

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56
Q

what can mathematical models predict

A

conditions under which reciprocity is favored by natural selection

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57
Q

what are evolutionary stable strategies (ESS)

A

mathematical models can predict conditions under which reciprocity is favored by nat selection

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58
Q

what did john maynard smith do

A

evo biologist; introduced game theory from econ to study evolution of social behavior

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59
Q

what is famous scenario

A

prisoner’s dilemma

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60
Q

prisoner’s dilemma

A

two individuals do better by acting selfishly, but if they both act selfishly they do worse than if they cooperate

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61
Q

what does game theory show about selfishness

A

selfish behavior is favored if individuals interact only once, but repeated interactions can favor cooperation

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62
Q

when is selfish behavior favored

A

if individuals interact only once

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63
Q

when is cooperation favored

A

repeated interactions

64
Q

describe prisoner’s dilemma

A

2 thieve commit crime, caught and isolated.

if they both defect & incriminate the other, each get 2 years in prison.

if both remain silent/cooperate, each get one year

if one defects and other doesn’t, one goes free other gets 3 years.

65
Q

what is best strategy in prisoner’s dilemma

A

only one defects

66
Q

what is worst strategy in prisoner’s dilemma

A

both defect

67
Q

what happens if these individuals interact repeatedly

A

strategy changes; gang members don’t rat each other out

68
Q

what is one kind of behavior w/ high fitness in interactions w/ other individuals

A

tit for tat

69
Q

describe this ‘tit for tat’ behavior

A

cooperate on first interaction, do whatever the other did on the previous round

70
Q

what is this ‘tit for tat’ behavior an example of

A

situation where individuals interact repeatedly

71
Q

what is cooperation

A

activity/behavior that provides a benefit to other individuals and to the actor

72
Q

what is altruism

A

involves behavior that enhances fitness of other individuals, but LOWERS fitness of the actor

73
Q

how can we explain altruism (in terms of what)

A

kin selection

74
Q

what is kin selection

A

helping out close relatives to increase their fitness

75
Q

when does kin selection favor altruism

A

only if individuals more likely to help kin than non-kin

76
Q

how do species recognize kin

A

cues, like distinctive calls or odors

77
Q

what is Hamilton’s rule

A

rB > C

78
Q

what is r

A

relatedness

79
Q

what is B

A

fitness benefit to recipient

80
Q

what is C

A

fitness cost to actor

81
Q

what does Hamilton’s rule say

A

relatedness times fitness benefit to the recipient MUST be greater than the fitness cost to the actor

82
Q

when is Hamilton’s rule met

A

when altruistic behavior can evolve

83
Q

what did JBS Haldane say

A

when asked if he would give his life to save a drowning brother, he said “no, but I would to save two brothers or eight cousins”

84
Q

why did JBS Haldane say that

A

relatedness; we share 50% genes w/ siblings and 25% w/ cousins

85
Q

what is better than us reproducing ourselves

A

saving two siblings or 8 cousins, cuz our offspring are only related to us by 50%

86
Q

what was Haldane referring to

A

inclusive fitness

87
Q

how much of genes do parents and offspring share

A

50%

88
Q

how much of genes do cousins share

A

25%

89
Q

who came up w/ idea of inclusive fitness

A

JBS Haldane

90
Q

what is inclusive fitness

A

the relative number of an individual’s alleles that are passed onto future generations, both directly AND indirectly

91
Q

how are individual’s alleles passed on to future generations directly

A

as a result of an individual’s own reproductive success

92
Q

how are an individual’s alleles passed on to future gens indirectly

A

when the individual helps relatives who also carry a proportion of their alleles

93
Q

what is this component due to indirect called

A

kin selection

94
Q

what was the idea behind inclusive fitness

A

relative # of someone’s alleles passed down are a combo of direct fitness and indirect fitness

95
Q

what does W.D. Hamilton’s rule say

A

selection favors genes for altruism if rB-C>0; ( relatedness of actor to the beneficiary * benefit in fraction of additional offspring resulting from helping - minus cost (in loss of offspring) to the actor from helping is greater than 0)

96
Q

what is W.D. Hamilton’s rule

A

rB-C > 0

97
Q

what does W.D. Hamilton’s rule say

A

altruism favored by natural selection IF

relatedness of actor to beneficiary x benefit to recipient (in fraction of additional offspring resulting from helping) - cost to altruist (cost in loss of offspring) is greater than 0

98
Q

what can we simplify this equation to

A

r > C/B

99
Q

what does r > C/B mean

A

genes for altruism more likely to spread when there’s genetic basis for behavior, benefits to recipient are great, cost to actor is low, and participants closely related

100
Q

when are genes for altruism more likely to spread

A

genetic basis for behavior, benefits to recipient are great, cost to actor is low, participants closely related

101
Q

talk about test of hamilton’s rule in pied-kingfishers

A

communal breeders that tunnel into mud banks. sex ratio biased towards males. have helpers at the nest; 2 types, primary and secondary helpers

primary helpers forgo mating for the first year, stay at natal nest to help raise siblings.
secondary helpers help unrelated pairs
delayers do nothing and wait until next year

60% of primary helpers breed the following year
91% of secondary helpers breed the following year
33% of delayers breed the following year

males do more helping
related individuals do more helping
secondary helpers do better than all the others the following year

102
Q

what are primary helpers

A

forego mating for first year and stay at natal nest to help raise siblings

103
Q

what are secondary helpers

A

help unrelated pairs

104
Q

what are delayers

A

do nothing and wait until next year

105
Q

what are results of kingfisher test

A

inclusive fitness is highest for a primary helper, high secondary helper, low for a delayer

106
Q

does it pay for secondary helper to assist non-relatives

A

yup

107
Q

another example of altruism in wild turkeys

A

wild turkeys display in pairs of dominant and subordinate brothers. dominant male has higher fitness.

presence of subordinate increases reproductive success of dominant male.

subordinate doesn’t mate, so cost of helping brother is cost of not displaying solo

108
Q

what was finding in turkey experiment

A

there is an inclusive fitness advantage to going solo; or advantage to this altruistic behavior of subordinate male

109
Q

what is most extreme cause of altruism

A

eusociality

110
Q

what is eusociality

A

colonies of individuals where most colony members do not reproduce and a few do

111
Q

what animals are in eusociality

A

naked mole rats, termites, ants, wasps

112
Q

what is eusociality

A

living in a cooperative group where one female and several males are reproductively active, nonbreeding individuals care for young, protect, provide for group

113
Q

what’s up w/ naked mole rats

A

only known eusocial mammals

114
Q

what are naked mole rats

A

diploid

115
Q

why are naked mole rats in a eusocial structure

A

cuz of harsh environment they live in

116
Q

what are famous examples of eusociality in insects

A

ants, bees, wasps, termites

117
Q

describe eusociality in termites

A

queen termite is attended by small, sterile workers and large-headed sterile soldiers

118
Q

what do ants do

A

engorged w/ nectar, hang from roof of nest’s ladder. they regurgitate nectar to worker nestmates

119
Q

what do wasps do

A

colonial nests

120
Q

what is involved in evolution of eusocial insects

A

kin selection likely involved

121
Q

what explains cooperation and conflict and why some individuals forgo reproduction and help their relatives in the haplodiploid system of relatedness

A

kin selection

122
Q

what does kin selection explain

A

in haplodiploid system of relatedness, kin selection explains cooperation and conflict and why some individuals forgo reproduction and help their relatives

123
Q

how are organisms related in diploids

A

offspring and parents are 50% related, siblings are 50% related

124
Q

what happens in haplodiploid systems

A

fertilized eggs are diploid, develop into females. unfertilized eggs are haploid, develop into males

125
Q

what happen to fertilized eggs in haplodiploid system

A

develop into females

126
Q

what happens to unfertilized eggs in haplodiploid system

A

develop into males

127
Q

so is the coefficient of relatedness the same in diploid system as it is in haplodiploid system

A

nope

128
Q

describe coefficient of relatedness in haplodiploid system

A

females are more closely related to sisters, r = 75%, than she is to offspring, 50%, and less closely related to brothers, r = 25%

129
Q

who are females most closely related to in haplodiploid system

A

her sisters, then offspring, then brothers

130
Q

what do social interactions often involve

A

conflict

131
Q

what must males and females do in order to produce offspring

A

cooperate

132
Q

but what else is pervasive between mates

A

conflict

133
Q

what is present between mates

A

conflict and cooperation

134
Q

what happens as effort by one parent increases

A

the other’s decreases

135
Q

what happens if you plot effort of male and female

A

intersection shows ESS; will evolve to ESS no mater what initial conditions are

136
Q

can conditions occur where optimal curves for sexes don’t intersect

A

yup; ESS is care only by female (scorpion) or male (poison dart frog)

137
Q

what else can conflict include

A

siblicide and infanticide

138
Q

who does siblicide

A

brown booby, owls, hawks, herons, pelicans

139
Q

when does siblicide happen

A

when food is limited

140
Q

does siblicide happen when food is plentiful

A

no, young don’t compete and parents raise a full nest

141
Q

who does infanticide

A

hyenas and lions

142
Q

when does infanticide occur

A

social cooperative mammals; males take over a harem/group of females, kill young so females can go into heat and reproduce

143
Q

what does infanticide do

A

eliminates alleles of competitors, allows females to become fertile and sexually receptive

144
Q

where does infanticide occur

A

social groups w/ more females than males

145
Q

can some species kill their own offspring

A

yup

146
Q

when do some species kill their own offspring

A

social situations where offspring survival would decrease even more if all offspring were allowed to compete w/ each other

147
Q

what is one last major form of conflict

A

cannibalism

148
Q

who does cannibalism

A

tiger salamanders

149
Q

when do tiger salamanders do cannibalism

A

when at high population density

150
Q

what kind of balance occurs in many biological systems

A

balance b/w conflict and cooperation

151
Q

what can males and females and parents and offspring have

A

aligned or conflicting interests

152
Q

what do ESS do

A

can predict which phenotype or balance of phenotypes is optimal

153
Q

what does altruism do

A

benefits other individuals, reduces individual fitness of the actor

154
Q

what does cooperative behavior do

A

increase individual fitness of both donor and recipient

155
Q

what does inclusive fitness explain

A

evolution of altruism

156
Q

what does individual selection explain

A

situations; behaviors

157
Q

what does kin selection explain

A

evolution of altruistic behaviors

evolution (15 decks)

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