chapter 16 Flashcards
Mutually beneficial interaction this is called
cooperative behavior
Behavior that increases fitness of recipient; to performer this is called
Altruism
what theory explains the evolution of cooperation among related individuals?
Inclusive fitness theory
Individuals DIRECT genetic success + genetic success of RELATIVES this is called
Inclusive fitness
What can increase inclusive fitness by helping close relative (kin selection) ?
Altrist
Additional benefit (B) obtained by recipient must be greater than cost to altruist (C), adjusted for degree of relatedness (r) between individuals this is called
Hamiltons rule (Altrism)
Degree of relatedness (r) varies
Close relatives=
Highest degree of relatedness
-should have highest amount of helping
Can kin selection explain evolution of alarm-calling behavior in ground squirrels?
-Alarm calls help close relatives avoid predation; production of alarm calls is costly (they increase the risk to the caller of being killed by a predator)
-Individuals near close relatives will most often produce alarm calls
(Belding ground squirrel alarm calls)
-Adult _____________ produce most alarm calls
-Adult _____________ and juveniles produce fewest alarm calls
conclusion:
_________________ explains variation in alarm-calling behavior observed
1) Females
2) males
3) Kin selection
Male turkeys form social ____________ (pair of males) display together to attract females (only dominant male mates) solo males display to females as solitary individuals
COALITIONS
Why do subordinates help the dominant male in a coalition in turkeys?
-Kin selection explains helping behavior in male turkeys
-for a subordinate male. B*r>C
For kin selection to operate, individuals must be able to discriminate kin from non-kin. How?
-Direct familiarization
-Indirect familiarization
individuals learn to discriminate kin from non-kin via previous ASSOCIATIONS this is called
Direct familiarization
Individuals learn a reference phenotypic cue from themselves or close relative. Assess degree of similarity of LEARNED CUE to cue in others this is called
Indirect familiarization
How do sticklebacks discriminate kin from non-kin?
1) individuals preferred FAMILIAR Kin to UNFAMILIAR non-kin
2) Sticklebacks learn kin via prior associations- evidence for DIRECT DISCRIMINATION
Kin discrimination (___________) in cockroaches
indirect
How do cockroaches discriminate kin from non-kin? Is odor from cuticular hydrocarbon profile (CHC) used?
1) Individuals preferred to associate with siblings or their CHC EXTRACT
2) INDIRECT FAMILIARIZATION based on CHC profile odor explains kin discrimination
In many species, unrelated individuals help one another this can be considered?
1) Byproduct mutualism
2) allogrooming
Individual’s behavior enhances own fitness and fitness of other
-cooperative behavior actually SELFISH; all group members (and joiner) benefit
EX) joining group increases hunting success of group
this is called?
Byproduct mutualism
Grooming of one individual by another to remove parasites
-altruism between unrelated individuals involves a cost to performer
this is called?
Allogrooming
How does cooperative behavior evolve between unrelated individuals?
Direct reciprocal altruism/ Direct reciprocity
A helps B, B helps A in future encounter
-Both individuals EVENTUALLY receive benefit that exceeds cost of helping
-subject to cheating; rare in nature
this is called
Direct reciprocal altruism/ Direct reciprocity
If cheating occurs _____________ cannot evolve
altruism
see image on prisoner’s dilemma page 23
What strategy results in evolution of direct reciprocity
Tit for tat
Player always COOPERATES in first interaction with partner
-matches the behavior of other player form previous interaction
-If both players use strategy, always cooperate on first encounter (and all subsequent encounters) —> HIGH payoff
-ALTRUISM can evolve
this is called
tit for tat
Why do vampire bats share blood meals?
1) RECIPROCAL ALTRUISM explains food-sharing behavior in vampire bats
2) Individuals will share food with those that have provided food in the past
(allogrooming in japanese macaques)
How can helping behavior among unrelated individuals evolve?
1) reciprocal altruism explains the evolution of helping such as allogrooming and support during an aggressive interaction
2) Individuals will help others who have helped them in the past
Why do neighboring blackbirds sometimes engage in cooperative nest defense against predators?
1) Reciprocal altruism and the tit for tat strategy explain cooperative nest defense behavior
2) individuals will cooperate only if their neighbor cooperating in the previous interaction
-Two individuals traveling opposite ways are confronted with snowdrift blocking the road.
Individuals:
-can obtain large benefit if can continue journey
-can pay effort cost to remove snow but both receive benefit of continuing travel
-can decide to not pay cost and hope other will remove snow, but if both fail to cooperate, neither will benefit
What is the best strategy?
1)HIGHEST PAYOFF do not cooperate with cooperator
-receive the benefit and pay no cost
2) Cooperate with cooperator
-receive benefit and pay half the cost
3) Cooperate with noncooperator
-receive benefit but pay cost
4) two noncooperators
-no benefit and pay no cost
ESS in such a game a MIXED strategy: cooperate some of the time or some fraction of cooperators exist in the population
Do migrating juvenile bald ibis exhibit both leading and following behavior during migration, cooperate some of the time, as predicted by the snowdrift game?
results:
-Positions within flock changed frequently
-individuals spent on average 32% of their time flying in the wake of another bird
-Direct swaps between a pair (leader became follower and vice versa) occurred FREQUENTLY
-Strong positive correlation between leading and following times
Conclusion:
-Birds were actively seeking follower positions, but individuals took turns leading
-Consistent with COOPERATION as modeled in the snowdrift game
-Individual A helps individual B because A and B help individual C in the past
This is called
-for this to evolve, indiciduals must keep track of other individuals reputation for helping _________________
1) Indirect reciprocity
2) Image score
Is there any evidence that animals use their knowledge of reputations to modify their altruistic behavior?
Clients appear to FORM IMAGE SCORES of cleaners and assess their propensity to interact cooperatively
Do great apes form image scores?
Chimps and orangs may form IMAGE SCORES of humans by observing interactions
Adults in social group forego breeding/help others raise offspring (“helper”) this is called
-Reproductive skew
Cooperative breeding
Variation in reproductive success among group members this is called
reproductive skew
High reproductive skew; helpers do not reproduce, but pay cost of care—-> altristic behavior. Why?
1) helpers closely related to breeding pair
-indirect fitness benefits
2) ecological constraints may limit breeding opportunities
-Have offspring is risky
-better to remain social and help rather than pay high cost of attempting to reproduce
Do helpers enhance the survivorship of pups and so, increase group size in meerkats?
1)pup food intake rate increased with number of helpers/pup
2) helpers enhance feeding rate and survivorship of pups.
-will increase group size/feeding benefits
-COMBINATION OF DIRECT AND INDIRECT BENEFITS
Why help other adults to raise their offspring in long-tailed tits?
Kin selection explains the evolution of helpers at the nest
-helpers are close relatives of the adult breeders
When few breeding opportunities exist, breeding attempt has LOW probability of success + HIGH cost
-individual have HIGHER fitness by staying in established group and helping raise others offspring this is called
Habitat Saturation hypothesis
Why do offspring stay at their natal nest and help raise offspring of their parents in seychelles warblers?
1) Habitat saturation limits breeding opportunities
2) If breeding opportunities existed, there would be fewer nests with helpers
(Social queuing in clownfish)
Clownfish live in small groups with 1 breeding pair and up to 4 unrelated individuals
-adults _____________- will mature into males, but can later become females
-females largest and most dominant, followed by dominant male, then non-breeders (no functioning gonads)
PROTANDROUS
Why do subordinates stay in social groups?
1) Subordinates can move up dominance hierarchy over time (SOCIAL QUEUING )
2) SUBORDINATES will obtain future reproductive benefits by staying in their group
Social structure with
-cooperative care of young (by nonparents)
-overlapping generations
this is called
Eusocial
In some species (order Hymenoptera) evolution of sterile workers ___________ (bees, ants, wasps)
-groups of individuals that engage in distinct behavior/possess distinct morphology
-sterile females- defend nest and help queen
-1-2 queens/colony
CASTS
Haploid males develop from unfertilized eggs
-diploid females develop from fertilized eggs
-sterile daughters achieve higher fitness by raising SISTER instead of daughters
this is called
Haplodiploidy genetic system
What are the problems with haplodiploid explanation?
Many eusocial species are DIPLOID
-average relatedness among siblings is same as parents and offspring (r=.5), so overall fitness benefits of helping to raise siblings isn’t higher than from raising offspring
-most likely due to KIN SELECTION and ecological constraints
What explains the evolution of sterile workers?
1) Kin selection
2) Ecological constraints
All extant eusocial species with sterile castes descended from MONOGAMOUS ancestor species
-all offspring were FULL SIBLINGS; related to one another on average, same as parents were to their own offspring this is called
KIN SELECTION
Most eusocial species live and reproduce large colonies; need COOPERATIVE defense
-small “break-off” colonies are likely to have low fitness; poorly defended
-May be few opportunities in an environment to establish a new colony because of HABITAT SATURATION
this is called
Ecological constraints
How do kin selection and ecological constraints play a role in the evolution of sterile workers in sweat bees?
1) female produce average of 4 larval cells in both solitary and multiple-female nests
-INCLUSIVE fitness of sterile worker females significantly higher than that of solitary females
2) Selection favors individuals that DO NOT reproduce directly, but instead stay to help a relative reproduce; HAMILTONS RULE
