Lecture 11: Populations: Dynamics of consumer-resource populations Flashcards
what have ecologists developed to study the dynamics of population growth and structure
three classes of spatially explicit models
3 modeling approaches with increasing level of complexity
- metapopulation models
- source-sink model
- landscape model
define metapopulation model
Describe a set of subpopulations occupying patches of habitat that individuals move between
define source-sink model
adds information habitat quality in
different patches to metapopulation model
define landscape model
Adds information on the differences in habitat within the habitat matrix - how surrounding habitat improves to source-sink
what does the metapopulation model measure
“patch occupation” through time
what does the source-sink model add to the metapopulation model
quality and directional movement data
what does the landscape model add to the source-sink model
data on habitat and barriers that alter movement
2 main sets of processes that the metapopulation has
- Growth and regulation of subpopulations – each subpopulation may have its own birth and death rates and growth dynamics.
- Colonization of empty patches and the extinction of existing occupied patches
what do metapopulation models capture
the dynamics of patch occupation and overall metapopulation persistence through time
factors impacting subpopulation dynaimcs
- Density-independent events have greater impact on small populations
- density-dependent factors
- movement between populations as a buffer
explain movement between populations as a buffer
- The more individuals move between subpopulations, the more subpopulation dynamics mirror the dynamics of the full population
- Zero or very little movement means each subpopulation has independent dynamics
- At intermediate movement, subpopulations go extinct but are then recolonized, creating a shifting mosaic of patch occupation
metapopulation model equation
pe = 1 - (e / c)
explain the metapopulation model equation
- pe = equilibrium proportion of occupied patches
- e = extinction rate of patches
- c = colonization rate of patches
metapopulation model equation - what happens when e < c
- the equilibrium population is positive
- this means the population is surviving
metapopulation model equation - what happens when e > c
the overall occupancy will decline to 0
metapopulation model equation - more complex/realistic models do what?
elaborate on the e and c parameters
Dynamics can be influenced significantly by incorporating the following factors into e & c terms:
- Different patch sizes within a metapopulation.
- Different rates of colonization for each patch.
- Different dispersal from each patch.
- Inter-dependent patch colonization and extinction rates
define rescue effect
The extent to which migration from large, productive patches can prevent small, unproductive patches from going extinct
what can have a big impact on population dynamics
- being eaten
- consumer population can limit the resource population
what are the consumer-resource interactions
- Predator-prey.
- Herbivore-plant.
- Pathogen/parasite-host.
how does the population cycle in regard to predator-prey interaction
- As the prey population gets bigger, its easier for predators to see and catch
- As the predator population grows, it starts to deplete prey, but time delay in reproduction
what is cycling driven by
a combination of time delays, overshooting, and density-dependent effects in both predator and prey
how do you get regular cycling
the more closely 1:1 predator-prey interaction is approximated, the closer to regulars cycling
