Communities of Organisms

 

A community is an association of populations of different species living in the same area. 

v  The effects of species interactions on communities:

o   Diversity of a community depends on the number of different species that live in the community and the relative abundance of those species.

 

o   Food webs consist of multiple food chains.

§  Food chains

§  Food webs

§  Producers

§  Consumers

§  Primary consumers

§  Secondary consumers

 

o   Keystone species have profound effects on communities.

 

§  Ex: Sea star-Pisaster ochraceus

 

v  Communities change over time.

o   Succession establishes new communities and replaces disturbed communities.

§  Succession

 

§  Climax community

§  Primary succession

 

§  Secondary succession

 

 

o   Communities change as climate changes.

 

 

o   People can cause long-term damage to communities.

 

o   Changes in communities affect their value to humans.

 

 

v  Recovery from disturbances:

o   Communities can recover from some human-caused disturbances.

§  EX: Lake Washington and eutrophication

 

§  Ex: Sea Turtles