Predator-prey interactions Flashcards
In which two ways is the abundance of prey species limited?
Top-down: predators limit the prey
Bottom-up: food availability limits the prey
What are the 4 forms of predation? How do they differ in lethality?
Carnivores: always lethal
Herbivores: generally non-lethal
Parasitoids: eventually lethal
Parasites: not lethal, but consume resources from the prey
What are 3 positive effects of predation?
Keeps prey below carrying capacity, removes individuals from the prey population that aren’t contributing to the next generation (old, sick, weak), removal of competitors
What are the direct and indirect effects of predators on prey?
Direct: consumptive effects of predators reducing the abundance of the prey (eating)
Indirect: non-consumptive effects just by having the predator around -> changes morphology, stress-physiology, behaviour
What are 5 non-consumptive effects predators have on prey?
Vigilance, habitat selection, grouping, inducible defences (morphology changes), fear
What are 5 assumptions of the Lotka-Volterra equations for predator-prey interactions?
- without predators, prey will grow exponentially
- predators are only limited by prey density
- predation is random
- all individuals are equal
- predator mortality is density independent
What are 4 general trends of predator-prey interactions?
- response of predators lags behind prey density
- oscillation pattern
- predator limits prey
- predators will eventually decrease from lack of food
What are 6 possible outcomes of predator-prey interactions?
- Predator goes extinct and the prey survive and grow
- Prey goes extinct and the predator goes extinct too or moves
- Oscillations that spiral into a stable point
- Oscillations that spiral out until one goes extinct
- Immediate stable limit cycle, reaches same maxes and mins every time
- Immediate stable point
How does predator-prey coexistence occur in nature?
Multiple predators, habitat heterogeneity, immigration, non-random predation
Which assumptions of the Lotka-Volterra equations are violated in nature?
- random predation
- all individuals are equal -> predators and prey have different generation times
- predators are only limited by prey density -> K may not have anything to do with prey density
What is stability through limits?
Having a carrying capacity for the prey prevents extinction. K stabilizes exponential growth and creates different angles which drive the cycle in
What are the 6 realities of predation?
- Predation is not random
- the carrying capacity of the predators may have nothing to do with the prey density
- Prey have refuges
- generation times are different between predators and prey
- predators can switch prey
- multiple equilibria may occur
What are the 9 adapted defences of prey against predators? What is an example of each one?
- Chemical (Bombardier Beetle)
- Protective armour (clams, porcupines)
- Batesian mimicry (Scarlet king snake)
- Mullerian mimicry (viceroy butterfly and monarch butterfly)
- Aposematism (poison dart frog)
- Deimatic behaviour (the screaming frog)
- Flashing colouration (white-tailed deer)
- Crypsis (leaf-tailed gecko)
- Object resemblance (katydid)
What is the difference between Batesian mimicry and Mullerian mimicry?
In Batesian mimicry, a harmless species mimics the warning colours of a dangerous species. In Mullerian mimicry, both species are dangerous and the colour signals are reinforced to predators in the area
When is herbivory considered to be predation?
When the plant is killed. Usually if a large amount of the shoots are eaten or the roots are eaten
