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


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