6.4: Review

Summary 

After completing this chapter you should be able to...

• Name and distinguish among the major types of biotic interactions, providing examples of each. 
• Describe how prey have adapted to reduce predation and how plants have adapted to reduce herbivory.
• Define energy and distinguish among the different types of energy.
• Explain the first and second laws of thermodynamics as they relate to trophic interactions in a community.
• Distinguish between and interpret food webs and food chains, explaining the advantages of each representation and identifying the trophic levels in each.
• Explain what limits the number of trophic levels in a community.
• Define symbiosis and provide examples.
• Explain the role of keystone species in maintaining community structure.
• Summarize the process of succession. 

Communities consists of populations of different species interacting in a common area. Biotic interactions describe the relationships among organisms, and trophic interactions, including predation, herbivory, and parasitism, are the biotic interactions that involve one organism eating another. Trophic interactions are diagrammed through food chains and food webs.

Some biotic interactions are not trophic. For example, competition is a biotic interaction in which one or both organisms that use the same resources are harmed, and it can occur between individuals of the same species (intraspecific) or between members of different species (interspecific). Facilitation refers to interactions in which one or both species benefit and neither is harmed. Examples include commensalism and mutualism. A symbiosis is a close association in which species are living together.

Communities are characterized by their structure (number and size of populations and their interactions) and dynamics (how the community structure changes). Keystone species have a great influence on community structure, which is disproportionately large relative to their abundance. Succession describes how community composition changes over time following a disturbance.

Attribution

Melissa Ha (CC-BY-NC)