lecture 5 Flashcards
(22 cards)
Generalist vs
Specialist
Generalist: all prey type
Specialist: 1-2 prey type
Specialist – energy lost searching ~ consume more profitable prey
* Generalist – consume less profitable prey ~ low energy searching
predation
An individual of one species (predator) consumes all or part of a
living individual of another species (prey)
Functional Response
the relationship between prey density and predator
consumption rate
Consumption rate depends on:
- prey abundance per unit area
(prey density) – all prey species - search efficiency for prey
(search time, s) - time to pursue, subdue & ingest prey (handling time, h)
3 types of Functional Response- type 1
Rarely observed
* search time varies with prey density
* Handing time is constant but near zero
The more prey there is, the more the predator eats — until a maximum is reached.
Why?
Predator just takes prey as it finds it.
Handling time ≈ zero (it takes almost no time to catch/eat prey).
Example: Filter feeders like whales eating plankton, spiders in webs.
Rare in nature because the more prey given= wouldn’t just keep eating more and more.
3 types of Functional Response- type 2
As prey density increases, consumption increases quickly at first, but then slows down and levels off.
Shape: Curved line that flattens
Why?
At low prey density: predator spends time searching → consumption is slow.
At medium prey density: prey is easier to find → consumption rises.
At high prey density: predator is busy handling prey, not searching → consumption levels off.
Most common in nature.
3 types of Functional Response- type 3
At very low prey density, predators barely eat. Then as prey becomes more common, consumption rapidly increases, then levels off.
Shape: S-curve.
Why?
At low density:
Predator doesn’t encounter prey often.
Predator may not recognize or ignore rare prey.
May be focused on other prey types (prey switching).
Prey have more cover, harder to find/catch.
As prey becomes more common:
Predator gets better at catching them.
Predator switches to focus on them.
What factors affect a predator’s consumption rate?
A: Prey density, search efficiency (search time), and handling time.
What is foraging theory?
how animals search for/ obtain food in a way that maximizes their energy gain while minimizing the cost
What does the diet model predict?
Predators switch between generalist and specialist strategies depending on search and handling times
Q: What is prey preference?
A: When a prey type makes up a larger proportion of the diet than in the environment.
What is intraspecific competition?
A: Competition between individuals of the same species for a limited resource.
What are the two types of intraspecific competition?
Exploitation (indirect) and Interference (direct).
What is the Ideal Free Distribution (IFD) model?
A model where individuals distribute among patches to maximize net energy gain, considering competitor density.
What are the key assumptions of the Ideal Free Distribution model?
S - Smart choices: Animals aim to get the most food (maximize energy gain)
* F - Free movement: They can move anywhere, no barriers
* R - Resources differ: Food patches vary in quality
* E - Equal ability: All animals are equally skilled
* E - Each gets less if more come: More animals in a patch means less food per animal
Why do handling and searching time increase at low prey densities?
not enough prey encounters to learn high capture efficiency
prey switching - switch to a more abundant prey type
high availability of cover for prey (refuge) at low densities
low, moderate, and high competition equals…
Low comp= just reduced growth
Moderate= low reproduction, and growth.
High= reduced growth, reproduction, and survival
How individuals balance attraction to high resource abundance=
aggregative response
repulsion by the presence of their competitors can be investigated using the
Ideal Free Distribution
prey patch selection depends on both _______ and _____________
densities
prey, competitor
A _______________ is the relationship between prey density and the
consumption rate of the predator and this can take three forms
functional
Foraging theory predicts the __________ strategy that predators should approach
to maximize fitness
this strategy will be favoured by natural selection
What prey to eat: the balance between energy __________ and
__________ (searching & handling) will determine the
__________ of a particular prey type and whether it is included in
the optimal diet
When the proportion of a prey type in the diet is higher than in the
environment that predator is exhibiting a _______________
optimal, energy gain, loss, profitability, preference
