Evolution of Social Behaviour

Question 1

Social interactions

Answer 1

Selfishness: The actor benefits at the recipient’s expense

Mutualism: Both actors benefit

Easy to explain by conventional natural selection
- Costs and benefits in terns of surviving offspring
- Selection occurring at level of individual (and gene)

Question 2

Benefits and Costs of Sociality

Answer 2

Benefits
- Increased vigilance
- Dilution effect
- Enhanced defence capability
- Cooperative foraging / hunting
- Improved defence of critical resources

Costs
- Increased conspicuousness to predators
- Increased competition for food
- Increased competition for mates
- Decreased certainty of paternity/ maternity
- Increased transmission of disease/ parasites

Question 3

Altruism

Answer 3

The actor incurs a cost and recipient benefits in terms of surviving offspring
- Would seem to reduce the actor’s fitness while raising a competitors fitness
Examples of:
- Allogrooming - social grooming
- Predator mobbing
- Co-operative breeding - helpers
- Adoption
- Eusociality
- Others?

Question 4

Group selection

Answer 4

Altruism evolution: Hypothesis 1

Traits can evolve that are costly to the individual as long as they benefit the group

• Organisms sacrifice their own fitness for the greater good
• Proposed as a mechanisms to explain why few cases of organisms out-stripping resources

Question 5

Kin selection

Answer 5

Altruism evolution: Hypothesis 2

Traits can evolve that are costly to the individual as long as they benefit kin (relatives)

• What appears to be altruism may actually serve genetic self-interest
• Darwin hinted that a trait could evolve that reduced fitness IF it increased the fitness of close relatives