Understandings:

• The distribution of species is affected by limiting factors.
• Community structure can be strongly affected by keystone species.
• Each species plays a unique role within a community because of the unique combination of its spatial habitat and interactions with other species.
• Interactions between species in a community can be classified according to their effect.
• Two species cannot survive indefinitely in the same habitat if their niches are identical.

Applications and skills:

• Application: Distribution of one animal and one plant species to illustrate limits of tolerance and zones of stress.
• Application: Local examples to illustrate the range of ways in which species can interact within a community.
• Application: The symbiotic relationship between Zooxanthellae and reef-building coral reef species.
• Skill: Analysis of a data set that illustrates the distinction between fundamental and realized niche.
• Skill: Use of a transect to correlate the distribution of plant or animal species with an abiotic variable.