13 - Evolution Social Behaviour

Question 1

Altruism

Answer 1

• Selfless concern for the welfare of others
• i.e. an act that benefits others at one’s own cost

Question 2

Grooming

Answer 2

• Beneficial for recipient (hygiene, relaxation)
• Costly for giver (time consumed)

Question 3

Examples of altruism

Answer 3

• Grooming
• Alarm calls
• Coalitions in conflicts
• Food sharing

Question 4

Group selection

Answer 4

• Once popular mechanism to explain the evolution of selflessness and altruism
• Competition among groups
• Groups vary in ways that affect their survival
• Some of this variation is heritable
• BUT selection acts on individuals

Question 5

How does altruism evolve?

Answer 5

Kin Selection

Question 6

Hamiltons rule

Answer 6

• An altruistic act will be favoured by selection when the following inequality is satisfied:
• rb > c

Question 7

Hamiltons rule explained

Answer 7

b = sum of fitness benefits to all recipients
c = cost to giver
r = coefficient of relatedness between them

Question 8

Coefficient of relatedness

Answer 8

• Measures genetic relationship between interacting individuals, or the average probability that they
  share an allele from a common ancestor
• Decreases as you become more distantly related (siblings 0.5, half siblings 0.25)

Question 9

Two important predictions of hamiltons rule

Answer 9

• Altruism should be directed towards kin (because r = 0 for unrelated individuals)
• Closer genetic relatedness allows for more costly altruism

Question 10

Kin recognition

Answer 10

• Phenotypic matching (smell or likeness to self)
• Contextual cues (familiarity, proximity, observe patterns of associations)

Question 11

Kin biases in altruistic behaviours

Answer 11

• Grooming more common among kin
• Coalitions
• Support directed towards kin

Question 12

Requirements of reciprocal altruism

Answer 12

• Must have opportunities to interact often
• Must be able to keep track of support given & received
• Must provide support only to those who help (satisfies the selective association condition for altruism to evolve)

Question 13

Can altruism evolve through natural selection

Answer 13

as long as altruists are more likely to associate with other altruists (whether kin or unrelated)