Chapter 14 Outline
Case Study: The First Farmers
Positive Interactions
CONCEPT 14.1 Positive interactions occur when neither species is harmed and the benefits of the interaction are greater than the costs for at least one species.
- Mutualism and commensalism are ubiquitous
- Mutualism and commensalism can evolve in many ways
- Positive interactions can be obligate and coevolved or facultative and loosely structured
- Positive interactions can cease to be beneficial under some circumstances
- Positive interactions may be more common in stressful environments
Characteristics of Mutualism
CONCEPT 14.2 Each partner in a mutualism acts to serve its own ecological and evolutionary interests.
- Mutualisms can be categorized according to their effects
- Mutualists are in it for themselves
- Some mutualists have mechanisms to prevent over-exploitation
Ecological Consequences
CONCEPT 14.3 Positive interactions affect the distributions and abundances of organisms as well as the composition of ecological communities.
- Positive interactions influence the sizes and distributions of populations
- Positive interactions can alter communities and ecosystems
Case Study Revisited: The First Farmers
Connections in Nature: From Mandibles to Nutrient Cycling
