Lecture 20: Predator-prey interactions. Flashcards
What are some examples of Exploitation interactions?
Predation
Parasitism
Herbivore
What do Herbivores eat?
They eat live plant matter, but do not kill the plant that they eat from
What do predators eat?
They eat, and kill the animal that they eat.
What are three main factors that influence prey populations?
- Food availability
- Predation
- non-consumptive effect of predators
What is the best example of predator - prey population dynamics?
The lynx and the Hare.
Their populations are highly dependent on the other
How do Hare populations affect Lynx populations.
When hare populations are high, Lynx populations are high.
When hare populations are low, hare populations are low.
What are the Consumption effects of predation?
direct effects
of predators on prey populations through the
capture and consumption of living prey
What are the Non-consumptive effects of predation?
changes
to prey that results as a consequence of
predators being present, including shifts in
morphological traits, stress-physiology, and
altered behavior
True or false:
Predators need to kill prey in order to impact the prey population
False,
When predators are simply within the environment there can me measurable affects on the prey species
When modeling predator - prey interactions, what is (H) and what is (P)?
H = Prey P = predator
When looking at the basic Exponential growth of the prey, what do teh following represent? (Slide 16)
Nh -
t -
rh -
Nh - prey population size
t - time
rh - prey pre-captia rate of increase.
True or false:
The Lotka-Volterra model for predation ignores intra-specific competition, assuming that predation will control population size, not competition.
This is true.
When attempting to model predation, what will (b) and (Np) represent
b = capture efficiency of the prey by the predators
Np = Predator population size.
What is Capture Efficiency (b)
The proportion of encounters between predators and prey that results in the predator capturing/eating the prey.
(the success rate of the predator)
If a predator catches 1 out of every 50 prey, what would be their (b) value?
0.02
When you include the growth of predator populations within the predation model,
what would
(c) and (dp) represent?
c = conversion factor of prey and predators
dp = per capita death rate of predators
When you include the growth of predator populations within the predation model,
what would
(c) and (dp) represent?
c = conversion factor of prey and predators
dp = per capita death rate of predators
What is the Conversion Factor?
Essentially how many prey are required to “produce” one predator How many prey individuals a female needs to consume to make one offspring
A predator needs to eat 5 prey individuals to have enough excess energy to produce an offspring, will have a (c) value of what?
0.2
When you set both equations (within the predation model) to zero, what will be plotted?
You will plot the isocline of net zero growth.
When you set both equations (within the predation model) to zero, what will be plotted?
You will plot the isocline of net zero growth.
How do plants avoid being eaten?
plants will be genetically selected for greater
Resistance & Tolerance
What is resistance?
something that makes them less likely to be eaten
What is tolerance?
something that reduces the harm with being eaten
What are two examples of plant defenses?
Toxins
Digestion-reducing compounds.
What are toxic plants more common in the tropics?
Tropical areas have more diverse communities of herbivores.
Due to this, there is more selective pressure to develop resistance or tolerance defenses. (thus there is a greater variety of defenses)
True or False:
Plants exhibit phenotypic plasticity in response to herbivory
True
What is phenotypic plasticity?
The ability of one genotype to produce more than one phenotype when exposed to different environments.
Is phenotypic plasticity short term or long term?
It is short term.
What is an example of phenotypic plasticity in plants?
The increased production of volatile in tomato in response to the infestation of spider mites
What are Constitutive defenses?
A result of phenotypic plasticity where defenses are produced
continuously, regardless of what happens to the
plant
What are Induced defenses
A result of phenotypic plasticity where concentrations of a defensive
chemical or morphology increase rapidly in
response to herbivore damage
What are the two major ways to avoid going extinct due to predation?
- Defense
- Just don’t get eaten in the first place. - Refugia
- populations are “rescued” from predation pressure by immigration.
What is Aposematic coloration?
A type of Defense: Camouflage and Coloration
- bright and conspicuous
coloration displayed by many toxic or distasteful
potential prey species
What is the advantage of Aposematic coloration?
You don’t have to actually be poisonous in order fro predators to think you are poisonous.
Is Protection in Numbers a type of Defense?
Yes,
Having populations so large that the risk of any one individual being eaten is low.
(just hope that one individual isn’t you)
What are the pros and cons of the “Size” defense Strategy?
Pros: you’re too big to
be eaten!
Cons: takes a lot of
energy to maintain
large body size
What is the Spatial Refugia strategy?
diel vertical migration by zooplankton
What is the Meta-population rescue Refugia strategy?
individuals from larger populations may immigrate and “rescue” smaller populations
What is (b)
The capture efficiency of the predator.
What is (c)
The conversion rate of prey into new predators
What is (dp)
Death rate of the predators per capita (have to multiply my population)
