Ch. 14: predation and herbivory Flashcards
introduced species (exotic species/non-native species)
species introduced to a region of world where it has not historically existed
invasive species
introduced species spreads rapidly and has (-) effects on other species, human recreation or human economies
mesopredators
relatively small carnivores consume herbivores
top predators
predators that consume herbivores and mesopredators
Lotka-Volterra model
model of predator/prey interactions
- incorporates oscillations
- shows predator numbers lagging behind those of preys
Growth Rate of prey populations =
dN/dt = rN - cNP
Growth Rate of predator populations =
dP/dt = acNP - mP
stable population = rate of change =
= 0
equilibrium isocline (zero growth isocline)
population size of 1 species causes population of another species to be stable
joint equilibrium point
point at which equilibrium isoclines for predator and prey population cross
joint population trajectory
simultaneous trajectory of predator and prey populations
functional response
relationship b/w density of prey and individual predator’s rate of food consumption
search image
mental image that helps predator locate and capture food
numerical response
change in # of predators through population growth or movement due to immigration or emigration
crypsis
camouflage that either allows individual to match environment or break up outline of an individual to blend in better w/ background environment
warning coloration (aposematism)
strategy in which distastefulness evolves in association w/ very conspicuous colors and patterns
Batesian mimicry
palatable species evolve warning coloration that resembles unpalatable species
- (unharmful) prey gains protection by resembling unpalatable/defended species
Mullerian mimicry
- 2+ species w/ similar effective defenses
- mutual/co-evolution of warning signs (red/yellow = danger)
- several unpalatable species evolve a similar pattern of warning coloration
community ecology
biological community w/ interacting species w/in defined area
- community lies b/w spatial scale
species interactions and (+)/(-)
competition (-/-), consumption (+/-), parasitism (+/-), mutualism (+/+), commensalism (+/N)
grazers and browsers
predator/prey relationship: herbivores
- grazers = eat grass (aquatic = algae)
- browsers = eat branches, twigs, shrubs, etc.
parasitoid
lays eggs and babies kill the host
- can limit abundance of prey
predators
- acquire energy by killing prey
- predators or groups of predators are larger than prey
parasites usually do not…
kill their prey
- but they can make you infertile or harm host
micropredator
small animals that feed off organisms (predators smaller than prey)
- do not directly kill prey
- vampire bats and mosquitos
effects of predators
- can influence prey populations
- introduced/non-native prey populations can be detrimental to environments (can do rapid damage)
Herbivores can have substantial effects on…
the species they consume
The effects of herbivores may be seen by…
fencing areas or removing herbivores to prevent grazing
The synchrony of population cycles between ___ and ____ suggests that these oscillations are the result of…
consumers and the populations they consume
- interactions between them
a predator-prey cycle:
normal prey population –> prey population increases –> predator population increase –> prey population decreases –> predator population decreases –> prey population increase…..
a predator-prey cycle assumes that…
- predators only eat 1 type of prey (“idealized relationship”
- assumption is usually not met (predator can prey on diff prey)
downfalls of the Lotka-Volterra model
oversimplified (doesn’t include):
- time delays
- density dependence
- real foraging behavior of most predators
downfalls of the Lotka-Volterra model
oversimplified (doesn’t include):
- time delays
- density dependence
- real foraging behavior of most predators
in order to have a not-oversimplified model, must include:
functional and numerical responses
Equilibrium (zero growth) isocline
the population size of one species that causes the population of another species to be stable
Joint population trajectory
the simultaneous trajectory of predator and prey populations
Joint equilibrium point
the point at which the equilibrium isoclines for predator and prey populations cross
If either of the populations (prey/predator) stray from the equilibrium point, they will…
oscillate around the point
Functional response
the relationship between the density of prey and an individual predator’s rate of food consumption
Whenever prey density increases and a predator can consume a higher proportion of those prey, the predator can…
regulate the growth of the prey population
Type I functional response
As prey density increases, predators consume a constant proportion of prey until satiation
Type II functional response
Any increase in prey density is associated with a slowing rate of prey consumption because of increased handling time
Type III functional response
when a predator exhibits low, rapid, and slowing prey consumption under low, moderate, and high prey densities, respectively
Type III response: Low consumption at low prey densities may occur for 3 reasons:
- Prey can easily find refuge to hide.
- Predators may have less practice at locating and catching prey but develop a search image at higher prey densities.
- Predators may exhibit prey switching by changing their diet preferences to the more abundant prey.
Populations of predators usually grow slowly relative to populations of their prey, but the movement of mobile predators can…
occur rapidly when prey density increases
adaptations: predators have evolved strategies to ____, but prey have evolved strategies to ____
- secure maximum amount of food w/ minimal energy expenditure
- to escape predation
3 types of adaptations
A change in:
- Physical (Structural)
- Physiological
- Behavioral
Structural Adaptations (physical or morphological adaptations)
a change in the physical or structural appearance of an organism
Physiological adaptations
a change in the production of either a noxious substance or an attractant
Behavioral adaptations
A change in the behavior of an organism that aids its survival
Predators that exhibit active hunting strategies spend most of their time…
moving around looking for prey
Predators that exhibit ambush (sit-
and-wait) hunting strategies….
lie in wait for a prey to pass by
Stalking is a combination of…
sit and wait and active hunting
Hunting can be thought of as a series of events, including…
detecting, pursuing, catching, handling, and consuming prey
Anti-predator defense
- concealment/camouflage (crypsis)
- mimicry
- structural (armor) or chemical defense
- ex: foul taste or smell
- fight back
- group together
types of mimicry
- mimicking other species (ex: something dangerous)
- mimicking other parts of its body (false eye or false head)
- mimicking nature (leaves, sticks, etc.)
costs of defenses
- reduced feeding activity
- crowding away from predators
- reduce growth, development, or reproduction of organism
Coevolution
when two or more species affect each other’s evolution; selection for prey defenses should favor the selection for counter-adaptation in predators
Structural defenses against herbivores
deter herbivores from consuming leaves, stems, flowers, and fruits
- ex: sharp spines, hair
Chemical defenses against herbivores
sticky resins and latex compounds that are hard to consume, and alkaloids (ex: caffeine, nicotine, morphine) that have a wide range of toxic effects.
Some plants employ the strategy of tolerating herbivory and can…
rapidly replace tissues that are consumed, or grow more tissue in areas that are not being consumed.
