Beneficial Interactions in Communities *Incomplete*

Chapter 9

Competition

An interaction where one species is negatively impacted, and the other is positively impacted

Mutualism

When both species benefit from an interaction

Commensalism

When one species benefits from an interaction while the other species is not affected

Facilitation

Any pairwise interaction in which one species benetits

Mutualisms and commensalisms

Foundation species

Species that provides structural habitat

Ex. mangroves

Ecosystem engineer

Species that modifies the environment

Ex. earth worms, beavers

Symbiosis

Intimate, persistant interaction between species

Ex. Nitrogen fxing bacteria in legumes

Partner fiidelity

Transmission of symbionts from parent to offspring

Ex. leaf-cutter ant queens and fungus

Partner choice

Select beneficial organims to pass along and/or help

Ex. N fixing bacteria choosing plants which provide other nutrients to them

Gause and Witt model

Only stable if interaction coeficient is <1