Interspecific Competition

• Superior and inferior competitor

• Rates of reproduction• Rates of growth• Tolerance to limiting factors• Direct competition

Mechanisms for superior competition

• Consumption• Preemption• Overgrowth• Chemical interactions

(allelopathy)• Territoriality• Encounter competition

Competitive Exclusion

Eastern cottontail

New England cottontail

Coexistence of Groton rodents

How can six species of salamander coexist on Groton School lands?

Coexistence

Resource Partitioning

Resource-based models

Spatially based models

Temporal Models

Changes over time (long-term)

Low levels of competition allow for extended persistence

Limiting Factor Models

Predation

Disease

Parasitism

Competition and Niche

• Fundamental Niche• Realized Niche• Resource Partitioning

– Spatial– Resource Selection– Timing?

Spatial heterogeneity and variation

• Environmental Gradients• Disturbance• Soil/bedrock• Aspect/topography

Temporal Variation

• Parameters that vary predictably over time– Temperature– Moisture– Seed and nut production– Prey population cycles

• Response of the inferior competitor– Dispersal– Dormancy– Reduction in density

Predation and Herbivory

Competition and Evolution

• Short-term changes– Behavioral

• Long-term changes– Structural

• Character Displacement

• Behavioral plasticity

How do so many New England carnivores persist in a small area?

Full Circle

• Why are the invasive species so successful in this system?• How do so many New England carnivores persist in a small area?• How can six species of salamander coexist on Groton School lands?

Competition and Conservation

Small Whorled PogoniaIsotria medeoloides