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Chapter 11 Outline

Case Study: Competition in Plants that Eat Animals

Competition for Resources

CONCEPT 11.1 Competition occurs between species that share the use of a resource that limits the growth, survival, or reproduction of each species.

Organisms compete for resources such as food, water, light, and space
Competing organisms reduce the availability of resources
Competition can increase in intensity when resources are scarce
Competition for resources is common in natural communities

General Features of Competition

CONCEPT 11.2 Competition, whether direct or indirect, can limit the distributions and abundances of competing species.

Species may compete directly of indirectly
Competition is often asymmetrical
Competition can occur between closely or distantly related species
Competition can determine the local and geographic distributions of species

Competitive Exclusion

CONCEPT 11.3 Competing species are more likely to coexist when they use resources in different ways.

Complete competitors cannot coexist
Competitors may coexist when they use resources differently
Competition can be modeled by modifying the logistic equation
BOX 11.1 What Do the Competition Coefficients α and β Represent?
BOX 11.2 When Do Competing Populations Stop Changing in Size?

Altering the Outcome of Competition

CONCEPT 11.4 The outcome of competition can be altered by environmental conditions, species interactions, disturbance, and evolution.

Disturbance can prevent competition from running its course
Evolution by natural selection can alter the outcome of competition