Community Ecology

Introduction to Community Ecology
- Interactive Exercise: Introduce interactions between species before discussing in-depth.

ENE-4.A: Describe community structure through species composition and diversity.
ENE-4.B: Explain how intra- and inter-species interactions shape community structure.
ENE-4.C: Relate community structure to energy availability in the environment.

Definition:
- An ecological community comprises all populations/species within a given area and the niches they occupy.
- Key Terms:
- Individual, Population, Community
- Structure Measurement:
- Community structure is represented through species composition and species diversity.
Key Concept:
- Natural selection leads to species competing for different ecological niches, influencing community structure.

Study Example: Evaluating the relationship between two species (A and B) by monitoring population changes post-introduction.
Types of Relationships:
- **Parasitism:
- Claim:** The graph indicates a parasitic relationship.
- Evidence: The introduction of Species B shows its population increase while Species A's decreases.
- Reasoning: B benefits while A is harmed, defining the parasitic relationship.

Species Composition and Diversity:
- Community structure is often detailed through species composition and diversity as per AP Bio CED guidelines.
Simpson's Diversity Index:
- Formula: $Diversity Index = 1 - Σ(\frac{n(n-1)}{N(N-1)})$
- Where:
  - $n$ = Total number of organisms in a particular species.
  - $N$ = Total number of organisms across all species.
Characteristics of a Healthy Community:
- Higher species richness (number of different species) and species abundance (number of individuals per species) indicate greater community health and resilience.
Biodiversity Measurement:
- Simpson's Biodiversity Index is used to quantify biodiversity.

Questions?
- Contact Deschamps for additional queries or clarification regarding community ecology.