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Community Ecology (Predator-Prey Interactions (One Predator, One Prey…
Community Ecology
Predator-Prey Interactions
One Predator, One Prey
Functional response
Predators feeding rates and its handling time.
Prey-dependent
Predators functional response is dependent on prey density.
Zero growth isocline
The line indication population growth stability.
Paradox of enrichment
Improving conditions for the prey may lead the predator to overexploit; loss of both species.
Maximum sustained yield-when the species is stable.
Fixed effort-harvesting populations health is determined by the amount of fish or deer.
Fixed quota harvesting-fisherman or hunters are allowed to harvest a particular amount.
Predator Selection Among Multiple Prey
Communities have multiple plant species that are prey to herbivorous predators.
Optimal foraging theory
examine the interactions between these factors in an attempt to understand why herbivores eat the plants they do while ignoring others.
Optimal diet model
Product of optimal foraging theory
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Makes four predictions:
2.If the high-yield prey become sufficiently scarce, then the predator would be more successful by broadening its diet to include prey that are lower in energy if they are abundant and easy to handle.
3.Some prey items will always be eaten if they are encountered, others will never be eaten even if easy to obtain.
1.Predators should prefer whichever prey yields the most energy per unit of handling time.
4.The probability that a particular plant will be eaten depends partially on the abundance of other plants that are easy to handle and have higher value.
Competition Between Species
Exploitation competition
Resource competition occurs when the organisms actually consume a shared resource, making it less available for others.
Interference competition
One organism restricts another organism's access to resources eve though the first might not be using it.
Resource-any factor or substance that can lead to increased growth rates as its availability is increased and that is consumed by an organism.
Apparent Competition
Apparent competition
Plants aren't actually competing for an using a resource
Diversity
Diversity and Scale
Scale matters
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Larger areas are more diverse
Larger areas will have more variation in:
Types of Soil
Topography
Geology
Species-area Relationship
The relationship between area and species richness
S+cA^z
Diversity and Latitude
varies with latitude
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Far northern areas in:
Canada
Siberia
Fewer species (lower diversity)
Alaska
Similar sized areas near equator:
Amazon rain forest
Central Africa
More species (higher density)
Southeast Asia
Communities consist of more than one species
Some communities have only a few species:
Salt Flats
Sand Dunes
Some communities have thousands:
Rain Forests
Beneficial Interactions Between Species
Mutualism
When two organisms interact such that both benefit
Also called mutualistic relationship
Facilitation
When one organism helps another without receiving any benefit
Primary succession
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When organisms become established on newly created substrates
Interconnectedness of Species: Food Chains and Food Webs
Food chains
The direct line of consumption
Food webs
A network of numerous interrelationships
Metapopulations in Patchy Environments
If several local populations are interconnected by migration and gene flow between the patches, the local populations are constituted as metapopulations
A community is a group of species that occur together at the same time and place.
