Optimal diet model

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What is the idea of optimal foraging theory?
Predators will evolve to hunt in the manner that is most efficient to their physiology and will maximize their fitness
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What needs to be true for an adaptation to be passed to the next generation
The benefits needs to outweigh the costs. /the adaptation is neutral.
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In an unproductive environment, what behaviour should predators adopt?
Generalist- be able to feed upon any food source they can find.
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Example of an experiment where a species showed generalist and specialist behaviour?
Bluegill sunfish- In an unproductive environment i.e few daphnia- generalist- fed upon all sizes. When placed in a tank with more prey- showed a preference for larger daphnia- better calorie payoff. EE Werner + DJ Hall. Ecology 1974.
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How did John Krebs use Great **** to show generalist and specialist behaviours in 1977?
In a lab- conveyor belt with mealworms- slow conveyor- birds ate any size that went passed them. When belt was sped up- then showed a preference for specific size class- highest energy for handling.
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What are the limitations of laboratory experiments testing generalist or specialist behaviours?
There are many factors involved affecting predation behaviour that may not be present in a lab- e.g. a need to avoid their own predators/ find mates
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How does bear behaviour change year to year when fishing for Salmon in Canada?
Years of good runs- selectively eats only the high energy parts of the fish e.g. brains. Years of bad runs may eat whole biomass of any fish caught.
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How do crabs choose which mussels to eat?
Choose a size where the mussel is still relatively big but the shell is not too thick that a lot of energy and time would be needed to break it, leaving it exposed to gulls for a longer time period.
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What are the benefits of living in a group?
Safety in numbers- more eyes to watch out for predators and food; dilution effect-less chance of being chosen as food; better defence in fighting off predators; more likely to find a mate; maximize time- one eats, one protects; take down bigger prey
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What disadvantages are there to group living?
Spotted more easily; more competition for food+mates; higher risk of contagion; inbreeding, cuckolding, cannibalism.
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How are prey distriubuted in space?
In patches
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How do predators distribute themselves in space?
Migrate to the most prey-dense areas/areas with less competition- fewer other predators
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What do we assume in the ideal free distribution?
Organisms have perfect knowledge of their environment e.g densities of prey in the area. and will move to the areas with the highest profitability.
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What happens to the ratio of different coloured prey after frequency independent selection takes place?
Nothing- the choosing should be random so the ratios should stay the same with the same number of prey of different colours taken from each.
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What happens to prey numbers if frequency dependent selection takes place?
The ratios of prey of different colours/sizes may change- there is a preference for the prey that is either most common or rare so one will be depleted more than the other changing the ratios.
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Why might some species select for rarity?
Easier to spot and predate upon.
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What were the findings in the Bradbury et al 2015 study?
Female gazelles were far more likely to graze in high quality areas with more abundant resources as it was easier to reach daily calories requirements.
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What happens when many individuals are attracted to one area? Who observed this?
The individual's share is depleted. Nicholson 1954.
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Why in the Ma et al, 2010 study did horseshoe bats sometimes hunt in locations with a higher predation risk?
When their food was more scarce- no other choice- worth the risk to go hunting.
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Why do Mantled howler monkeys sometimes throw away large sections of the leaves they eat?
When preferred plants= abundant. - Choose to eat newer leaves with higher protein/less fiber and less tannins. Glander 1981.
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Compare positive and negative frequency dependent selection.
Positive- common becomes more common, rare becomes more rare. Negative- common becomes less common, rare becomes less rare.
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Why might P.longicosta limpets not eat all the alga they come across straight away?
Choose to tend "gardens of alga" which they manage and defend to ensure a reliable food supply Branch 1975. Mechanisms reducing intraspecific competition in Paella spss. The journal of animal ecology pp575-600
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What is apostatic selection?
Selecting the most common variety of prey
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What is anti-apostatic selection?
Selecting the rarest varieties of prey
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Other cards in this set

Card 2

Front

What needs to be true for an adaptation to be passed to the next generation

Back

The benefits needs to outweigh the costs. /the adaptation is neutral.

Card 3

Front

In an unproductive environment, what behaviour should predators adopt?

Back

Preview of the front of card 3

Card 4

Front

Example of an experiment where a species showed generalist and specialist behaviour?

Back

Preview of the front of card 4

Card 5

Front

How did John Krebs use Great **** to show generalist and specialist behaviours in 1977?

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Preview of the front of card 5
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