Community Ecology Flashcards
Community
All the organisms that inhabit a particular area
Assemblage of populations of multiple species living close enough together for potential interactions
Symbiosis
Interaction between two different species usually living in close physical association
Inter specific interactions
Interactions with individuals of other species in the community
Inter specific interaction examples
Competition
Predation
Her ivory
Parasitism
Mutualism
Commensalism
A negative/negative interaction occurs when
Individuals of different species each use a resource that limits the fitness of both individuals
Competitive exclusion
Two species cannot coexist permanently in a community if their niches are identical
Exploitation
Any type of positive/negative interaction in which individuals of one species benefit by feeding in individuals if another species
Exploration includes
Predation, parasitism, and herbivory
Predation
One species kills and eats the other species
Parasitism
One species gets nutrients from another organism which is thereby harmed
Positive interactions
At least one individual benefits and neither is harmed
Mutualism
Both species benefit from their interaction
Commensalism
Interaction that benefits one species but neither harems or helps the other species
Species diversity
The variety of different species in the community
Species richness
Number of different species in the community
Relative abundance
Proportion each species represents if all individuals in the community
Caveats
Determining number and relative abundance of species jc challenging
Why is determining the number of species challenging?
Most species in a community are rare
Difficult to get large sample size
Difficult to identify
Difficult to census
Microorganisms
Community sustainability
Higher diversity communities are generally more productive and able to withstand and recover from environmental stressors
Factors that affect community structure
- Climate patterns
- Geography
- Heterogeneity (patchiness) of the environment
- Frequency of disturbances or disruptive events
- Interactions between organisms
Trophic structure
Feeding relationship between organisms
Food chain
Transfer of chemical energy from its source in primary producers to primary consumers to secondary and tertiary consumers and eventually decomposers
Trophic level
Position an organism occupies in a food chain
Foundation species
Have strong effect in communities as result of large size or high abundance
Ex trees, desert shrubs, kelp
Often provide habitat or food for members of the community
Keystone species
Exert control on community structure NOT because of their abundance but because of their pivotal ecological role
Ex sea stars
Ecosystem Engineers
Species that create or dramatically alter their environment
Change the physical environment and amount of resources available
Ex beavers
Bottom up control
Abundance of organisms at each Trophic label is limited by nutrient supply or food available at lower Trophic levels
Controlled from the bottom of the food chain
Top down control
Abundance of organisms at each Trophic level is controlled by the abundance of consumers at higher Trophic levels
Controlled by the top of the food chain
