48: Community Interactions I. Types of Interaction

A. Neutral: Two populations do not significantly affect one another.

B. Commensalism: One population benefits, in is unaffected.

C. Mutualism: Both populations benefit.

I. Types of Interaction

D. Parasitism: One species benefits, one suffers. Pest is usually smaller and doesn’t kill host.

E. Predation: One species benefits, one suffers. Predator usually larger than prey and kills prey.

F. Interspecific Competition: Both species suffer due to competition for same resource.

Useful Summary

Species 1 Species 2

Neutral

Commensalism

Mutualism

Predation

Parasitism

Interspecfic Competetive

I. Types of Interaction

Symbiosis: Two species live in close contact.

Which types of interaction would be considered symbiotic?

a.

b.

c.

II. When two species compete:A. Shared Niche:

Niche: The role a species plays within a given habitat. Space used, food comsumed, etc.

Rule of Competitive Exclusion: If two species have significant niche overlap, one will outcompete the other.

Niche or Resource Partitioning: Within an ecosystem, each population utilizing the habitat in a unique manner.

II. When two species compete:

B. Warning Coloration: Outer appearance warns others of potential danger.

C. Mimicry: One species benefits by having coloration similar to another species’ warning coloration.

III. Community Change

A. Succession: The change in a community over time.

III. Community Change

B. Primary Succession: The first life reaching a habitat.

1. Pioneer Species: Species well adapted to colonizing an available niche.

2. Climax Community: The (relatively) stable community that will come to dominate a habitat.

C. Secondary Succession: The introduction of a new community after a disturbance of an already established community.

• Flood

• Forest Fire

• Prairie Fire

III. Community Change

III. Community Change

r- strategist K-strategist Small size Large

Quick life cycle Long life cycle

Lots of energy into Little energy into

reproduction reproduction

Example Example

Succession

Early Successional Stage:

K or r?

Diversity?

Stability?

Late Successional Stage:

K or r?

Diversity?

Stability?

III. Community Change

D. Keystone Species: A species with a particularly vital role in a community.