Community Ecology
Concepts
Diversity
Predator-Prey Interactions
Beneficial Interactions Between Species
Metapopulations in Patchy Environments
Food Chains and Food Webs
Community
A group of species that occur together
Community ecology
The interactions between populations #
Succession
The more-or-less predictable sequences
Climax community
When a community alters habitats to benefit only them
Habitat won't benefit invasive species
Community restoration
Important because humans are members of communities
Habitat loss and fragmentation
Species checklist
Number of species present in a community
Diversity and scale
Scale
The size of a plot of land used to study diversity
Species-area relationship
Expressed by the formula S=cA^z
Species abundance distribution
Number of species in each abundance class
Diversity and Latitude
Areas near the poles have lower diversity
The equator has higher for the same scale
One predator, one prey
Functional response
Predator's feeding rate and handling time
Prey-dependent
S-species, A-area, c and z are constants
Lotka-Volterra model models net rate of prey change
dN/dt=rN-aNP
dN/dt-rate of change, r-intrinsic rate
N-number of prey, a-predator's attack rate, P-number of predator
Zero growth isocline
Line indicating population stability
Paradox of enrichment
Where predators overexploit prey, both species are lost
Maximum sustained yield
Point where growth goes from positive to negative
Fixed effort harvesting
Population health is determined by the amount of harvesting
Fixed quota harvesting
The amount of harvesting people can have
Predator selection among multiple prey
Optimal foraging theory
Attempts to understand why herbivores eat the plants they do
Optimal diet model
Makes four predictions
- Predators prefer which prey yields most energy
- Predator would be more successful in broadening diet
- Some prey will always be eaten, others will sometimes
4.Probability of being eaten depends on abundance
Competition between species #
Exploitation competition
Organisms consume shared resources
Interference competition
One organism restricts another's food source
Invasive species
Species that increase population despite competitors
Resource
Any substance that can lead to an increased growth rate
Apparent competition
When one plant species decreases due to predation
Another species increases as a result
Mutualism
Two organisms benefit from each other
Facilitation
When one organisms helps another with no benefits itself
Nurse plants
Alter area around them to suit seedlings
Primary succession #
Organisms become established on newly created substrates
Metapopulation
Populations interconnect through migration and gene flow
- Patches of land are suitable for life
- Some patches hold life, others don't
- Empty patches will be colonized
- Probability of extinction within patches
Source and sink habitat
High-quality and low-quality patches
Fugitive species
Colonizes a patch, flourishes, colonizes more patches
Assisted dispersal
Animals are captured in one area, released in another
Food chain
Direct line of consumption
Food web
Network of interconnected food chains
Energy flow web
Keystone species
Flow of energy through webs
Species that has an out of proportion impact
