Predation (ch. 12) Flashcards
Why do we have data on population sizes on lynx and hares going back 200 years?
Because of the fur trade that went on in the early 1900s
Lynx and Hare populations peak around every ____ years
10
Hare populations rise in _______
synchrony
Why will a population grow?
Surplus of resources
Why will a population decline?
Decrease in resources
What happens when thee hares decline?
the lynx decline also because their food supply runs out
What happens to food supplies when the hare population density is high
Food supplies becomes limiting
What explains the drop in survival rate?
Predation by the lynx and other predators
What happens to hare birth rates during decline phase?
they drop
What happens to hare numbers after predator numbers plummet?
They rebound
Predation
individuals of one species (predators) benefit by feeding on, and directly harming, individuals of another species
Carnivory
prey are animals
Herbivory
Prey are plants or algae
Parasitism
Lives symbiotically on or in their prey (its host) and consumes certain tissues; may not kill the host. some parasitic pathogens cause disease.
Example of an herbivore
elephant
Parasitoids
Insects that lay eggs on or in another insect host. After hatching, larvae remain in the host, which they eat and usually kill.
a host is a great ____ for a parasitoid, why?
Niche, because the host is a home and food source to the parasitoid.
Some predators subdue prey with _____ and ____ into their environment
poisons, blend
Some predators can _____ or _____ chemicals made by prey
detoxify, tolerate
Adaptations to escape being eater
Large size
rapid movement
body armor
Warning coloration (aposematic)
predators learn not to eat brightly colored organisms because they tend to be toxic
Crypsis
prey are camo and resemble its background
mimicry
prey resemble another organism that is toxic or very fierce
masting
when plants produce a large number of seeds in one year and hardly any in the following year
compensation
removal of plant tissue stimulates new growth
how do plants hide from herbavores?
by producing a great number
Plants structural defenses
Tough leaves
spines
thorns
saw-like edges
pernicious hairs that pierce the skin
Induced defenses
produced in response to herbivore attack
secondary compounds
toxic chemicals used to reduce herbivory
True/ false: predator populations can cycle with their prey populations
true
Where do insights from population cycles come from?
Models
experiments
field studies of predator-prey interactions
When prey abundance is high, how will that effect predators?
Increase in population size
What about when prey abundance is low?
Decrease in population
When predator abundance is high?
the prey will decline
When predator abundance is low?
prey will increase
What is the equation for exponential growth
dN/dt= rN
dN/dt =
the rate of change in population size at each instant in time
r =
exponential population growth rate per capita intrinsic rate of increase
Death due to predation= what factors do you think matter?
How many predators
how many prey
how fast they are
how good they are at capturing their prey
Equation stating that when prey are abundant, death due to predation will increase
dN/dt=rN-aNP
Change in prey population over time:
population growth equation for prey - dN/dt=rN-aNP
N= number of prey
P= number of predators
r= population growth rate
a= capture
What is the population growth equation for the predator?
dP/dt=baNP-mP
b =
efficiency with which prey are converted to predator offspring
m =
mortality rate
predator birth is dependent on what?
how much predators eat
Isocline
Zero population growth line
When will prey populations not change?
P=r/a
prey population decreases when?
P>r/a
prey population increases when?
P<r/a
Isocline for predator population
N=m/ba
predator population increases when
N> m/ba
Predator population decreases when
N< m/ba
Lotka-Volterra model
suggests that predator-prey populations have an inherent tendency to cycle because the abundance of one population is completely dependent on the abundance of the other population.
Three- way feeding relationships
effects of predators and prey on each other, coupled with effects of prey and their food plants on each other
factors that can prevent predators from driving prey to extinction:
Habitat complexity and limited predator dispersal (as in Huffaker’s mites)
Prey switching (other food sources) in predators
Spatial refuges (where predators cannot hunt effectively)
Evolutionary changes in prey populations
What does stress result in for hares?
The production of cortisol
What does cortisol effect
