optimal behaviour

Question 1

what is the optimal foraging theory?

Answer 1

Foraging maximises the rate of obtaining energy

Question 2

marginal value theorem

Answer 2

a theorem that postulates that foraging animals should use the information at hand to predict the future value of a resource and to quit when that value reaches a level that makes the current behaviour no longer worthwhile

Question 3

trade off between foraging and vigalence

Answer 3

foraging: gets more energy
vigilance: won’t get eaten

Question 4

what does the marginal value theorem assume

Answer 4

• environment consists of patches containing energy

- takes ‘fixed time’ to move between patches

Question 5

what does evolution increase?

Answer 5

survival value in a constant environment

Question 6

caveats

Answer 6

Behaviour may not be optimal if the environment changes

Animals are subject to constraints, e.g. information about environment, ability to move

Question 7

rate of getting energy

Answer 7

energy obtained from patch/ travel time + time in patch

Question 8

cowie experiment

Answer 8

• mealworms in plastic cups on a tree in the experimental aviary
• wild bird put in aviary one at a time
• lids on cup to increase travel time
• 2 treatments: short travel or long travel

Question 9

kacelnik experiment on starling

Answer 9

• central place foraging theory

- starling goes to get food and returns to nest

Question 10

milinski and heller experiment and conclusion

Answer 10

• sticklebacks eating water fleas (Daphnia) either with or without a model predator.
• in the absence of predators hungry stickleback generally went for the centre of the swarm, but if a model kingfisher was flown over the tank they switched to the edge.
• Stickleback optimise survival by trading foraging for vigilance when there are predators around

Question 11

simpson experiment

Answer 11

• tested optimal diet using final instar catepillars

- compared protein eaten against carbs eaten

Question 12

cowie’s experiment conclusion

Answer 12

short travel time spent shorter time in patch

longer travel time spent longer time in patch

Question 13

central place foraging theory

Answer 13

animals collecting food and returning to a fixed point (central place) like a nest

Question 14

optimal prey choice e.g. shore crabs eating mussels

Answer 14

• bell shaped curve

- choose mussels from the most profitable size class

Question 15

Elner and hughes experiment and conclusion

Answer 15

• Each crab was offered equal numbers of mussels of each size class
• measured the energy content of each size class, recorded how long it took crabs to open the shell and calculated profitability = (energy content)/(time to open shell).
• they predicted the crabs would select mussels from the most profitable size class.