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Chapter 18 Outline

Case Study: Powered by Prairies? Biodiversity and Biofuels

Community Membership

CONCEPT 18.1 Species richness differs among communities due to variation in regional species pools, abiotic conditions, and species interactions.

Species supply is the “first cut” to community membership
Abiotic conditions play a strong role in limiting community membership
Who you interact with makes all the difference in community membership

Resource Partitioning

CONCEPT 18.2 Resource partitioning among the species in a community reduces competition and increases species richness.

Resource partitioning allows more species to coexist along a resource spectrum
Studies of resource partitioning show that specialization is the main mechanism of coexistence

Nonequilibrium Theories

CONCEPT 18.3 Nonequilbrium processes such as disturbance, stress, and predation can mediate resource availability, thus affecting species interactions and coexistence.

Nonequilibrium theories are alternatives to resource partitioning
The intermediate disturbance hypothesis explains diversity under variable conditions
There have been several elaborations on the intermediate disturbance hypothesis
The lottery model relies on equality and chance

The Consequences of Diversity

CONCEPT 18.4 Experiments show that species diversity is positively related to community function.

Relationships between species diversity and community function are positive
Hypotheses explaining diversity–function relationships are numerous