Optimality Theory

Optimality Theory

• The optimal behaviour needed to maximise fitness depends on 2 factors:
  • Natural Selection should favour individuals that display optimal behaviours.
  • Individuals should be maximised to increase survival chances - behaviour should be optimised.

Optimal Feeding Behaviour

• Elner & Hughes (1978) offered mussels of varying sizes to hungry shore crabs
• Why aren't the largest chosen cosistently?
• Why do the crabs sometimes forage on very small and very large mussels?
  • One reason might be time to search for another prey item
  • A model of foraging behaviour can be produced that incorporates:
    • Handling time
    • Energy values
    • Searching time

Big vs Small Model

• If crab encounters the 'perfect' mussel it should always eat it (no bigger profit)
• But...it should only eat a small mussel if...
  • Gain from eating > gain from rejection and searching for larger mussel
    • I.e. Es/Hs > El/ Sl+Hl
      • E = energy
      • H = handling time
      • S = searching time

Prey selection in Great ****

• Krebs et al. (1977) tested model predictions

• Presented with large (profitable) and small (unprofitable) mealworm pieces on a conveyor belt
• 'Search time' was varied
• Bird…