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Chapter 26 Community Ecology - Coggle Diagram
Chapter 26 Community Ecology
Concepts
Community - group of species that occur together at the same place and time.
communities can exist in other communities
Communities have boundaries in time
Succession is the predictable sequence of changes in a community
Climax community - a stable self-aintaining community
Community Restoration - process of attempting to restore a community
Diversity
Species checklist- a count of the number of species in a community
Diversity and Scale
Scale is greatly important when studying any aspect of a community
A larger area will have more species
species-area relationship - the relationship between area and species richness. Represented by S=cA^z
S is the number of species, A is the area, c and z are constants that must be discovered by studying individual communities
Gamma diversity is the number of species in a region
Alpha diversity is the number of species in a small, local site
Beta diversity compares differences between several small sites within a larger region
Various levels of scale
Region - area larger than a few kilometers but less than a continent
Biome - large area characterized by plants present
Local - Small area less than a few kilometers
Biogeographical region - extremely large region that usually coincides with a continent
Diversity and Latitude
Diversity varies greatly with latitude
places farther north typically have less species
Predator-Prey Interactions
One Predator, One Prey
One species of prey attacked by only one species of predator
Not true in nature but is a helpful model
Two fundamental aspects of predator-prey relationships
Feeding rate - how quickly a predator finds a new prey individual
Handling time - time needed for predator to consume prey
Both come together to form a predator's functional response
We harvest many species from the environment
Maximum sustained yield - Is the maximum amount we can healthily harvest from a species
Fixed effort harvesting - population health determined by the amount of something that can be harvested with a particular amount of effort
Fixed quota harvesting - where fisherman or hunters are allowed to harvest only a set amount
Predator Selection among multiple prey
3 main factors influence a predators choice of prey
decision to attack an individual once encountered
Probability that the prey will be successfully eaten
Probability of encountering certain species
Competition Between Species
Interspecies Competition - Several species compete for same resource
Exploitation Competition - when one organism consumes a resource thus making it less available for others
Interference Competition - One organism restricts another's access to resources
Beneficial Interactions Between Species
Mutualism - when two organisms interact in a way that benefits both
Facilitation - One organism helps another without receiving any benefit
Metapopulations In Patchy Environments
metapopulation - Several local populations are interconnected by migration and gene flow between the patches
Common model of these makes four assumptions
Some patches are occupied by the species, whereas other suitable patches are not
Empty patches will become colonized by migration from occupied patches
A region of the environment is composed of many discrete patches in which the species can live
Populations within individual patches have a probability of going extinct with that patch
Low quality patch is a sink habitat
high quality patch is a source habitat
Interconnectedness of Species: Food Chains and Food Webs
small communities usually have 3 trophic levels
Primary consumers (herbivores)
Secondary Consumers (carnivores)
Primary Producers (plants)
Food web - interconnected web of predator/prey relationships. Most are not accurate
Keystone Species - a species that dramatically affects the structure of their community. This impact is not proportional to their actual numbers
