Interactions - Predation Dynamics Flashcards
Lotka Volterra Model
This assumes prey consumption rate by a predator is proportional to the prey abundance, so feeding is limited only by amount of prey.
Two composed of Lotka-Volterra…
P is amount of predators and N is prey in biomass
What type of equation is Lotka-Volterra Model…
Differential equation
Assumption of no predators equation…
Exponential increase of prey; dN/dt - rN
Denote r
Intrinsic rate of natural increase.
What does prey decrease rate depend in presence of predators?
Frequency of prey-predator encounters and numbers of prey and predators present.
Successful competition depends on efficiency…
dN/dt = rN - aPN
Predator equation of starvation…
dP/dt - -qP
Define predator birth…
Rate of food consumption(aPN) and predator efficiency f defines rate of predator birth
Equation of predator birth rate…
dP/dt = faPN - qP
Zero-growth Isocline
This refers to set of population sized where rate of change for one population in a pair of interaction population in zero.
Zero Isoclines
Connecting points of equal gradient in inclination.
Lotka-volterra model properties derived…
Zero isoclines where x axis is prey density and predator density the y axis.
When is rN = aPN?
When prey rate of increase is dN/dt
When is faPN = qP?
When predators dP/dt = 0
Predators in a zero isocline…
N being constant, left prey is low and predators decrease, right prey is high and predators increase.
Coupled Oscillations
This means changing on regular basis of lots of predators with few prey to lots of prey with few predators.
Delayed density dependence effects on lotka-volterra..
Prey may not fluctuate instantly due to reproductive output time delays
How does delayed density dependence differ from direct?
Delayed results from a function of the past.
Other models of predator-prey fluctuations…
Type 1 functional response
Type 2 functional reponse
Type 3 functional response
Type 1 Functional Response
Depicts a linear increase in consumption rate until satation, then no change in consumption rate above satation
Why are functional responses better?
Incorporate REAL features into lotka-volterra models.
What does Type 1 Functional Response assume?
Consumption rate increases linearly with prey density(a)
Type 2 Functional Response
The rate of prey consumption by predator rise as prey density increases, with an eventual asymptote
What causes Type 2?
Handling time of the prey(increased prey density increases handling times)
Type 3 Functional Response
This is where predators increase their search activity with increasing prey density
Mast Years
This is where synchronous production of a large amount of seeds in intermeidated by low production years, commmon in tree species suffering high seed predation.
Dynamics of mast years…
In mast years, more chance escaping seed predation, due to satation.
Over-production of seeds being energy costly, inhibiting plant growth, re-mediated by following low-growth years.
Example of mast years…
The cicads 7-13-17 year cycles.
When cicadas are born…
Within 3-4 weeks emerging, adults climb to canopy and feed/mate/oviposit.
Why do cicadas cycle in prime numbers?
Because it is harder for predator birth cycles to adapt.
Mutual Interference
Is interference among individuals of the same species or population.
What limits prey abundance?
Prey or other predators.
Ratio Dependence
A type of predator dependence which depends on ratio of prey to predator populations, not on abosolute numbers of either species.
Example of competition limiting consumption rate…
Spending more time defending nectar stores, increasing with more competitors there are
What does dN/dt = -qP describe?
Rate of change of a population over time to model growth or decline of populations with dN/dt proportional to product of N and per capita rate of resource consumption q
What does the the negative sign in dN/dt = -qP indicate?
Population decreases as resources are consumed.
What does q represent?
Per capita rate of resource consumption
What does dN/dt = -qP suggest?
Rate of change of population is negatively related to resource availability, population size decreasing as resources deplete.
What does dP/dt = faPN-qp describe?
Interactions of populations and resources, suggesting population growth rate is influenced by resource availability and conversion efficiency of resource into population growht(as population size increases, per capita rate of resource consumption increase, with decrease in population growth rate.
What does -qP represent?
Per capita rate of resource consumption, depending on resource consumption and population size.
What does faPn represent?
Per capita rate of population growth due to reproduction, depending on population size, resource availability and resource conversion efficiency?
What does f mean in equations?
Per capita rate of population grwoth achieved without resource limitations.
What does value f depend on?
Population age structure, reproductive strategies and environmental conditionss.
