Predation 1 Flashcards
eating another organism is
exploitation
what is the difference between herbivory and carnivory
carnivores kill. herbivores do not usually, however reduce fitness of, and reproduction
what is the optimal foraging theory?
what does it depend on?
tells about dietary specialization
it relies on the encounter rate, and the handling time
encounter rate:
time it takes to search and find prey
handling time
time it takes to subdue/ consume/ digest prey
herbivores tend to be
why?
exception??
-specialists
-because plants are tough to digest and require adaptations to be efficient
-grasshoppers are generalist
what do most herbivores eat, and why?
leaves,
because they are abundant and nutritious, sometimes year round
some specialize on roots
what are the 2 types of herbivores
-grazers
-browsers
Grazers
feeds on nutritious rich, low growing non-woody shit
cows and horses
browsers
feed on nutrient poor stuff thats high growing, like leafs or twigs
effect of successful predation: herbivores vs carnivores
-carnivores is obvious, death
-herbivore doesnt immediately kill however
in grasses, a predation event
stimulates growth
The effect of geese grazing on grass growth
above ground biomass decreased,
HOWEVER, primary productivity increased
Productivity of grass only elevated with
Light grazing, feces is like fertilizer, occurs in early summer
if criteria not met, productivity and biomass decrease
Carnivores tend to have
broad diets, generalists
carnivores eat prey in relation to their availability
what is the exception
dont show preference
exceptions–lynx and coyote eat primarily hares
Prey Switching also known as
-predators concentrate on whatever prey most abundant
-frequency dependent predation
-what adaptions do cheetas have for catching prey
-what are the tradeoffs
-specialized for bursts of speed
-trade off: stamina not great
snake adaptations for prey
-skull bones not not rigidly attached
-consume prey larger than their heads
komodo dragons
-venom
-anti coagulates, prey bleed out
mimicry
mimic surroundings and ambush mfs
garter snake
detoxify poison,however puts them in a vulnerable position
what are prey populations affected by?
-Food availability
- consumtive effect on predators
-non consumptive effects on predators
Lynx and hare - predator prey dynamics
-pops go through cycles where they peak every 10 years
-affected by lynx and other factors
consumptive effect of predation
direct effects of predators on prey population through capture and consumption
Non consumptive effects of predation
due to predators being present, morphological, stress physiology, and behaviour changes
when does non consumptive effects change reproduction rates
results when direct consumptive effects of predation are high
What happens to hares when there is high predation rate
-high numbers of predators even with low predation rate:
-mfs got high blood cortisol lvls
- dont reproduce as much
applies to when dogs are present aswell, even if dogs dont eat them
Dugongs(sea cows) response to tiger shark density
go deep so they avoid predators, even if less food
if given enough food hare pop
how does supply and predation affect this?
grows exponentially
hella mfs get eaten, heavy browsing induces chemical defences of plants aswell, food shortages cause a decrease in pop
the lotka volterra model for predation ignores
competition
prey subscript
H
predator subscript
P
Predator prey dynamics
- describe population growth of prey
–> change in num of prey over period of time
2.add in predation as a factor –> THE BREAK to the prey pop growth
what is b?
capture efficiency
–> success rate of predator
if pred catches 1 out of 50 prey–>
capture efficiency is 1/50
what is c?
conversion factor–> how many prey to produce one predator
if Np > rh/b
prey pop decreases
Np < rh/b
prey pop increases
number of prey is on what axis?
the X axis
