Cooperation

Question 1

What defines cooperativity?

Answer 1

Co-operator pays cost, c
Recipient gets benefit, b
Cooperator specifically evolves to give this benefit (so predation does not count)

Question 2

How are cooperative behaviours maintained in a population?

Answer 2

Selfish individual = increased individual fitness = spreads through pop = reduced overall fitness

Question 3

What is the ‘Tragedy of the Commons’?

Answer 3

Arms race of selfishness - no benefit to being fair in a society where no one else is, so each individual becomes increasingly exploitative

Question 4

Direct benefits of cooperation?

Answer 4

Reproductive success of co-operator increases

Question 5

Example of direct benefits from reciprocity?

Answer 5

Cleaner wrasse - clean parasites from eels who could just eat the fish, but let them live (and give them a food source) so as to benefit from parasite removal

Question 6

Indirect benefits of cooperation?

Answer 6

Reproductive success of an individual sharing the cooperators genes is increased

Question 7

What is altruism?

Answer 7

Behaviours that benefit only the recipient - cannot result in cooperator benefitting later

Question 8

Reciprocal altruism example?

Answer 8

Vampire bats blood sharing - can regurgitate blood to give to those who have not found any food.
May end up having this returned later, but from a different source

Question 9

Indirect reciprocity

Answer 9

Often in humans - this is where the cost is repaid much later. It may also contribute to social status e.g. cheaters get no cost or benefit, and may have reduced reputations

Question 10

What is kin selection?

Answer 10

Favouring of traits because they improve the fitness of others

Question 11

Hamilton’s rule

Answer 11

rB - C > 0

benefits of cooperating exceed costs, dependant on r = level of relatedness

Question 12

How can we test Hamilton’s rule?

Answer 12

See if animals can recognise their relatives, and behave differently as a consequence
e.g. tiger salamanders cannibalise, found to have delayed onset of this if raised in groups with relatives

Question 13

How do animals recognise kin? (3)

Answer 13

Environmental cues
Phenotype - self-reference matching
‘Green-beard’ effects

Question 14

Environmental cues signalling kin?

Answer 14

Offspring born in the same nest, at the same time are likely to be related
Cues learnt from this environment e.g. acoustic indicators, odour (MHC similarity), appearance

Does not indicate degree of relatedness

Question 15

Phenotype and self-referent matching?

Answer 15

Essentially if they resemble another - this does allow degree of relatedness to be determined

Unfamiliarity leads to longer time spent investigating; unfamiliar kin are recognised more easily, familiar kin the easiest

Question 16

Green beard effects

Answer 16

Signal or marker, often leading to increased tendency for co-operative behaviour.
Cheating is observed so it is not always effective, but honesty is maintained by a high cost of cheating

Question 17

Inclusive fitness? plus example

Answer 17

Cooperation leads to this, where inclusion in a group increases overall fitness.
e.g. mating coalitions in turkeys, where dominant and subordinate males are related and dominant males receive a benefit from them

Question 18

Inclusive fitness equation?

Answer 18

IF = direct fitness +r(indirect fitness)

Question 19

When will cooperation evolve?

Answer 19

If it can offer direct and/or indirect fitness benefits

Question 20

What is cooperative breeding?

Answer 20

Helpers assist in raising another children, at the cost of their own reproduction.

Question 21

Commonality of cooperative breeding?

Answer 21

3% of birds
2% mammals
0.1% fish

Question 22

Hypotheses for cooperative breeding? (3)

Answer 22

Kin selection
Life history constrains
Ecological constraints

Question 23

Kin selection argument for cooperative breeding?

Answer 23

Relatives still possess an individuals genes and so they gain inclusive fitness benefits

Question 24

Life history constraints argument for cooperative breeding?

Answer 24

Delayed maturity
Low adult mortality (too large a pop. for many breeders)
No/limited dispersal (as above)
Low reproductive rate

Question 25

Ecological constraints argument for cooperative breeding?

Answer 25

Shortage of territory/mates
-e.g. fairy wrens, loss of male breeder causes helper to move into the position
High dispersal costs
Low independent breeding success (e.g. in harsh environments)

Question 26

What is the habitat saturation model?

Answer 26

In context of cooperative breeding - occurs when there are insufficient territories.
In warblers introduced to a new island, cooperation only occurred once all territories were full

Question 27

How do helpers aid breeders?

Answer 27

May supply food, resources, guarding
i.e. increase food delivery rates, as parents can only reach a certain level which may be insufficient with increased offspring numbers

Question 28

What do helpers directly gain?

Answer 28

Pay-to-stay in group membership (protection, food from group)
Breeding experience
Territory/mate inheritance e.g. fairy wren with removal of breeding male
May attempt to breed

Question 29

What do reproductive skew models show?

Answer 29

Dynamics between helpers and breeders - where helpers may be allowed to breed as payment for helping (concessions) or because they are large enough to escape risks, or helpers do not breed due to reproductive restraints

Question 30

Concessions in cooperative breeding?

Answer 30

Breeders offer incentives to induce helpers to remain, e.g. letting them reproduce
Needed with unrelated groups or better territories

Question 31

Restraints in cooperative breeding?

Answer 31

Helpers opt out of reproduction e.g. in a relative-dominated group to prevent inbreeding, if breeders can punish them, or if surrounding territories are poor

Question 32

Promiscuity in cooperative breeding?

Answer 32

It decreases relatedness, found to be correlated in nature with reduced cooperativity

Question 33

What does direct reciprocity depend on?

Answer 33

Repeated interactions to help both cooperator and recipient, relies on memory