The evolutionary function of behaviour

The evolutionary function of behaviour

1. Designing agent = Selection

   • Acts to sift variants of behaviour, favouring those that provide their bearer with greater representation in the next generation

2. How does Natural Selection work in practice?

   • 1) Huge numbers of individuals are produced.
   • 2) Insufficient resources for all, so many die before reproducing.
   • 3) Individuals vary in attributes.
   • 4) Individuals with attributes better suited to environment are less likely to die.
   • 5) These individuals will be over represented in next generation.

3. Individuals differ in reproductive output

4. Differences in fecundity; no. offspring they can produce

5. Attractiveness

6. BEHAVIOURS = trade off between selective forces

7. Behaviours function to maximise:

   • Likelihood of long-term survival
   • Lifetime reproductive output

8. Behaviours that maximise survival

   • 1) Hiding from predators
   • 2) Escaping from predators
   • 3) Increasing amount of food eaten
   • 4) Reducing energetic costs

9. Behaviours that aid reproduction

   • 1) Increasing attractiveness
   • 2) Increasing access to mates
   • 3) Increasing fecundity
   • 4) Increasing survival of young

10. Behaviours that improve reproductive success

    • 1) Increase chances of being attractive to females during the fertile period
    • 2. By increasing access to mates (normally males wanting to find females) during a fertile period
    • 3. Behaviours that reduce the cost to ‘self’ and hence enable increased chances of future reproduction (i.e. increasing fecundity in the long-term
    • 4. Increasing the survival rate of young and decreasing overall costs to ‘self’

11. Dysfunctional behaviour

    • Direct benefits to individual performing behaviour
    • Indirect benefits but others (kin?) can benefit too
    • Indirect benefits but ultimately offspring benefit
    • Symbiosis between unrelated species / individuals

12. EPISTASIS is a phenomenon whereby the expression of one gene depends upon the presence of the others around it. A gene can be expressed or repressed by the other genes around it.

13. Divergent evolution

    • Evolution of different features from a common ancestor; resulting in differences between species.

14. Convergent evolution

    • Evolution of similar features in unrelated species due to similar environmental pressures.

15. 1. When did the behaviour arise?

    • Parsimony: “The process that requires the least number of changes.”

16. 2. Why did the behaviour arise?

    • Pre-existing behaviour.
      • Ritualisation or co-option “Integration of pre-existing behavioural elements into novel contexts.”
    • Pre-existing bias.
      • Sensory exploitation “Stimulating physiological, neurological and psychological biases previously evolved in a different context.”
    • Adaptive Co-evolution
      • “Coordinated change between two (or more) elements of ecology/morphology/behaviour.”

17. Complicating factors

    • 1. Missing species
      • Fossil record incomplete?
    • 2. Changed environment
      • Response to localised climatic change - increase fitness long-term
    • 3. Changed Selection Pressures
      • Behaviours can change the selective pressures on future generations