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 1Species 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

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.