Optimal Foraging

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What is the 'Optimality Theory'?
Analyses and quantifies fitness costs and benefits. Are trade-offs.
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What are costs of a food item?
Time, danger, toxins
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What are the benefits of a food item?
Energy, water and nutrients (macro or micro)
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What is an adaptation?
Hereditary trait that has spread through natural (or sexual) selection and is replacing alternative traits because it has a better fitness-benefit vs fitness-cost ration than alternatives
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What is 'Direct fitness'?
Reproductive success e.g. number of copulations
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What does Direct Fitness depend on?
Health, survival and ability to attract mates
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What are 'decision making adaptations'?
Evolved these to make sensible choices, to maxismise fitness benefits vs fitness costs by being maximally efficient in all things that lead to fitness
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What is the first stage of the Optimality Theory?
Decision variable - Identify the problem. Do this before solution - what decision is organism trying to make?
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What is the second stage of the Optimality Theory?
Currency variable - choose correct currency. Need to know to calculate costs vs benefits
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What is the third stage of the Optimality Theory?
Constraint variable - identify alternatives and constraints. Need to identify alternatives that decision is choosing between and constraints e.g. need for certain nutrients may limit flexibility
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Why is evolution a 'blind process'?
Not trying to achieve anything. Selection cannot anticipate future needs, works on current ones.
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What are the limits on the evolution of traits?
Physical, environmental, developmental and historical. E.g. pigs cannot fly.
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What is the fourth stage of the Optimality Theory?
Quanitfy costs and benefits of alternatives to see which decision yields biggest fitness benefit.
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What is the final stage of the Optimality Theory?
Assume that appropriate genetic variation has arisen in organisams evolutionary history and the population is at an evolutionary equilibrium.
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What are the assumptions of the Optimality Theory?
Genotypic variations have arisen and that we are looking at the END of the process - we are observing stable solutions. Organism is at an evolutionary equilibrium.
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What are the general Optimality Theory/Analysis views?
Broad applicability. Selection is an optimising agent. Ultimate currency = fitness. Ongoing selection and variation over generations will hone phenotypic solutions to problems.
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What are the pros of using the Optimality Theory to look at foraging decisions?
Easy to quanitfy e.g. by calories
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What are the failures of the Optimality Theory?
Evoutionary lags - sudden environmental change - previously optimal situation non-optimal
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What is Interspecific Brood Parasiticm?
Animals bring up other animals offspring. E.g. cuckoo birds - lay eggs in other birds nests. Bigger birds so get fed more, host bird assumes better survival of bigger bird chicks
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Why does Interspecific Brood Parasiticm work?
Use rule of thumb - if in my nest, must be my chick
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Examples of foraging decisions?
Searching for prey. Capturing Prey. How to search? Where to search? When to search? What prey?
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How has natural selection improved foraging efficiency?
Shaped animals to make decisions to make them efficient foragers.
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What makes an organism an efficient forager?
Deciding where to look, what kind of food and when to move on
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What can maximising efficiency do?
Maximise profitability
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What are the assumptions of animal foraging?
Behaving in a sensible way (to maximise benefits and reduce costs). Evolved adaptations (anatomical, physiological and behavioural traits) for profitable feeding. Must make trade-offs (can't do everything perfectly).
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What are the main choices animals make on food?
Which types of food to eat and where to hunt.
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What is handling time?
Time it takes animal to subdue and eat prey
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What is profitability?
Benefit (net food value)/costs
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How can researchers distinguish between profitability of prey?
Handling time - animal spends more time handling it, assume it's more profitable
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What is an Optimal Strategy?
strategy for which fitness benefits-cost payoff exceeds alternative strategies. Is the 'optimal outcome'.
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How can animals determine profitability of food?
Use rules of thumb
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What cues of profitability can a predator use?
Size, movement and colour
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What are 'Rules of thumb'?
Approximations of perfect decisions. Most cost-effective way of making decisions. Specific to environment organism is in.
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Failures of rules of thumb?
May make mistakes. Novel environments = bad outcomes.
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What trade-offs do most animals make?
High selectivity (increases search time) vs low selectivity (reduces profitability)
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Why might behaviours look like sub-optimal foraging decisions?
Low availability of profitable food
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Predictions for foragers?
Be more selective when profitable prey is abundant. Show preference for profitable prey. Ignore unprofitable prey that are outside optimal regardless of their abundance.
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Other cards in this set

Card 2

Front

What are costs of a food item?

Back

Time, danger, toxins

Card 3

Front

What are the benefits of a food item?

Back

Preview of the front of card 3

Card 4

Front

What is an adaptation?

Back

Preview of the front of card 4

Card 5

Front

What is 'Direct fitness'?

Back

Preview of the front of card 5
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