C.1 Species and Communities

Essential Idea

• Community structure is an emergent property of an ecosystem.

Understandings

1. The distribution of species is affected by limiting factors.

2. Community structure can be strongly affected by keystone species.

3. Each species plays a unique role within a community because of the unique combination of its spatial habitat and interactions with other species.

4. Interactions between species in a community can be classified according to their effect.

5. Two species cannot survive indefinitely in the same habitat if their niches are identical.

Applications

1. Distribution of one animal and one plant species to illustrate limits of tolerance and zones of stress.

2. Local examples to illustrate the range of ways in which species can interact within a community.

3. The symbiotic relationship between Zooxanthellae and reef-building coral reef species.

Skills

1. Analysis of a data set that illustrates the distinction between fundamental and realized niche.

2. Use of a transect to correlate the distribution of plant or animal species with an abiotic variable.

Key Vocabulary

• Species

  • Distribution

  • Limiting factors

    • Limits of tolerance

    • Zone of stress

  • Keystone

• Community

  • Competitive exclusion principle

    • Niche

      • Fundamental vs. Realized

• Transect

  • Distribution of biotic vs. abiotic variable

Textbook Reading and/or Activities

Click HERE for a pdf of chapter 9.

• Pages 423-440

  • TOK (p.429)

  • Worked Example (p.430)

  • Challenge Yourself (p.431)

  • Worked Example (p.432)

  • Worked Example (p.434-435)

  • Challenge Yourself (p.435)

  • Worked Example x2 (p.436-437)

  • Challenge Yourself (p.437-438)

  • Exercises (p.440)

Notes

C.1 Species and Community

A detailed set of notes, prepared by Bob Smullen, examining U1-U5, A1-A3 and S1-S2.

i-Biology Notes

A detailed set of notes, created by Stephen Taylor, examining U1 - U5 and S1 - S2.

Bioknowledgy Notes

A detailed set of notes, created by Chris Paine, examining all of the IB learning expectations.

Bob Smullen Ecology Review

A series of questions, prepared by Bob Smullen, to help check your understanding of both Topic 4 and Option C based on Ecology. This is VERY GOOD practice.

Learning Activities

Virtual Lab - Population Biology

This virtual lab, prepared by McGraw-Hill, will help you better understand how competition and limiting factors influence the growth of bacterial populations.

Chi-Squared Test

This activity, prepared for the American Statistical Association, will help you better understand how to determine whether or not a statistically significant difference exists between two data sets.

Supplemental Reading

Abiotic vs. Biotic

This reading (<15 mins), prepared by Diffen, clearly outlines the differences between abiotic and biotic components of the environment. It includes a relevant SlideShare and two videos to help clarify each concept.