Common relationships among various species within natural communities. Species Interactions Common relationships among various species within natural communities.

Population – group of individuals of the same species living in the same area, potentially interacting Community – group of populations of different species living in the same area, potentially interacting What are some ecological interactions?

Why are ecological interactions important? Interactions can affect distribution and abundance. Interactions can influence evolution. Think about how the following interactions can affect distribution, abundance, and evolution.

Types of ecological interactions competition predation (predator/prey) arasitism (parasite/host) mutualism commensalism symbiosis

Competition – two species share a requirement for a limited resource  reduces fitness of one or both species

Predation – one species feeds on another  enhances fitness of predator but reduces fitness of prey

Parasitism – one species feeds on another  enhances fitness of parasite but reduces fitness of host

Mutualism – two species provide resources or services to each other  enhances fitness of both species

Commensalism – one species receives a benefit from another species  enhances fitness of one species; no effect on fitness of the other species

Symbiosis – two species live together  can include parasitism, mutualism, and commensalism

Organizing ecological interactions effect on species 1 + 0 - predation herbivory parasitism + - commensalism mutualism effect on species 2 competition