Predation and Herbivory Flashcards
Introduced species
A species that is introduced to a region of the world where it has not historically existed.
Also known as exotic species or non-native species
Invasive species
An introduced species that spreads rapidly and has negative effects on other species, human recreation, or human economies
Parasitoids
Live within the tissues of a living host and consume them inside out until they eventually die
Biological control
Introductions of one species to help control the abundance of another species
Mesopredators
Top predators
Relatively small carnivores that consume herbivores
-coyotes, weasels, feral cats
Predators that typically consume both herbivores and mesopredators
-wolves, lions, sharks
Lotka-Volterra model
A model of predator-prey interactions that incorporates oscillations in the abundance of predator and prey populations and shows predator number slagging behind those of their prey
Growth rate of prey population over time equation
dN/dt=rN-cNP
rN=growth of prey population based on intros is growth rate
cNP=loss of prey due to predation
NP=random encounter between predator and prey
c=capture efficiency
Growth rate of predator population equation
dP/dt=acNP-mP
acNP= birth rate of the predator pop
cNP= number of prey consumed by predator pop
a=efficiency of converting consumed prey into offspring
mP=death rate of predator population
m=per capita death rate
A prey population of stable when it’s rate of change is _____
0
0=rN-cNP
Or rN=cNP
Or P=r/c
Therefore prey population will be stable when the number of predators equals the ratio of preys growth rate and the predators capture efficiency
When will the prey population increase
When rN>cNP
Or P<r/c
When the addition of prey (rN) exceeds the consumption of prey (cNP)
When is predator population stable
0=acNP-mP
Or
acNP=mp
Or
N=m/ac
When the production of new predators is equal to the mortality of existing predators
When will the predator population increase
acNP>mP
Or
N>m/ac
Equilibrium isocline
The population size of one species that causes the population of another species to be stable. Also known as zero growth isocline
Joint population trajectory
The simultaneous trajectory of predator and prey populations
Joint equilibrium point
Point at which the equilibrium isocline for predator and prey populations cross
-no change over time
-if either pop strays from this point, then oscillations begin again
Looks volterra model does not include what
-time delays
-density dependence
-real foraging behaviour of most predators and herbivores
Functional response
The relationship between the density of prey and an individual predators rate of food consumption
Type 1 functional response
When predators rate of prey consumption increases linearly with an increase in prey density until the predator is satiated
-negligible handling time
-spiders, whales
Type 2 functional response
Predators rate of prey consumption begins to slow down as prey density increases and then plateaus when satiation occurs
-handling time keeps predator from catching another prey for a certain period
Ex: true predators (BOA CONSTRICTOR)
Type 3 functional response
Prey consumption increases slowly when prey population density increases form very low numbers, consumption is rapid when prey population density is moderate, and slow prey consumption under high prey densities
Greater success as predator when prey are more abundant: decreased search time, prey switching
Search image
A learned mental image that helps the predator locate and capture food
Numerical response
A change in the number of predators through population growth or population movement due to immigration or emigration
Most common behaviour defences
-alarm calling
-spatial avoidance
-reduced activity
Crypsis
Camouflage that either allows an individual to match its environment or breaks up the outline of an individual to blend in better with the background environment
Warning colouration or aposemstism
A strategy in which distasteful ness evolved in association with very conspicuous colours and patterns
Batesian mimicry
When palatable species evolve warning colouration that resembles unpalatable species
Müllerian mimicry
When several unpalatable species evole a similar pattern of warning colouration
Coevolution
When two or more species affect each other’s evolution
True predators characteristics
-lethal
-many prey
-consume all or most parts
-tigers, polar bears, seed eating rodents
Grazers characteristics
-not predictably Lethal
-many prey
-consume parts
-sheep, cows
Parasites characteristics
-not lethal in short term
-one or few prey
-consume parts
-tape work, fluke
Parasitoid characteristics
-lethal (slowly)
-one
-consume whole
-10% of all species (flies and wasps)
Folivory
Predation on leaves
Short term effects of folivary
-loss of photosynthetic and transpiration rate
-loss of stored minerals
-decreased total carbon fixation?
-increased photosynthetic rate (temporary)
-decreased nutrient acquisition
-decreased self shading
-increased induction of secondary metabolites
-lignification of leaves
Negative effects on plant fitness (progeny) depend on:
-part of plant affected
-timing of development
-frequency and duration of attacks
-spatial pattern of damage
-type of damage (chewers, suckers..)
-resource availability
Compensation recovery of effects of herbivory
-removal of shade leaves= photosynthesis increases in leaves that used to be shaded
-altered sink: source relation: increased activity of remaining sources or reduced demand
-reduced seed abortion
Where more or less fruits produced by plant that was damaged
More, less abortion
Natural herbivory’s result on shoot growth
-if apical meristem is damaged, it will release dominance and develop into more shoots
Pollen production and leaf damage
The more leaf damage, the more seeds sired by pollen grains
Tolerance
Ability for plants to keep growing and or reproduce after herbivory
Needs to be estimated by
-clones
-full sib
-half sib
Common depictions of tolerance
Underestimation: greater fitness when undamaged
Exact compensation: equal fitness with damaged or undamaged
Overcompensation: greater fitness when damaged
Constitutive plant defence
Induced plant defence
Always expressed in the plant
Appear or increase in concentration after herbivory
Defence
Traits that reduce the negative fitness consequences of herbivory
Resistance
Tolerance
Reduce the likelihood of attacks
Ability to maintain fitness despite loss of tissue to herbivores (having thick skin)
Induced response involves use of
Production of secondary metabolites: phenols, tannins, alkaloids, terpenoids, lignin etc.
-C or N based
Direct costs of defence
Resources used for production of defensive compounds or compensation cannot be used simultaneously for other functions (growth, reproduction)
Opportunity costs
Resources used in defence early in ontogeny have an effect later on
Costs of defence
Self toxicity- most plants he toxin in vacuoles or enzymes separately that only mix when herbivory takes place.
Defence against one species may attract another
Functional response
Relationship between the rate of prey consumption by an individual predator and the density of the prey
Numerical response
Change in the number of predators due to population growth or movement of individuals
Evolution of defences (types)
Behavioural
Crypsis
Structural
Chemical
Mimicry
Müeller and batesian mimicry
Mimicry in which the organism does have ability to defend still
Mimicry in which the organism has no defence other than the mimic
