Categories
There are two basic categories of facilitative interactions:
- A mutualism is an interaction between species that is beneficial to both. A familiar example of a mutualism is the relationship between flowering plants and their pollinators. The plant benefits from the spread of pollen between flowers, while the pollinator receives some form of nourishment, either from nectar or the pollen itself.
- A commensalism is an interaction in which one species benefits and the other species is unaffected. Epiphytes (plants growing on other plants, usually trees) have a commensal relationship with their host plant because the epiphyte benefits in some way (e.g., by escaping competition with terrestrial plants or by gaining greater access to sunlight) while the host plant is apparently unaffected.
Strict categorization, however, is not possible for some complex species interactions. For example, seed germination and survival in harsh environments is often higher under so-called nurse plants than on open ground. A nurse plant is one with an established canopy, beneath which germination and survival are more likely due to increased shade, soil moisture, and nutrients. Thus, the relationship between seedlings and their nurse plants is commensal. However, as the seedlings grow into established plants, they are likely to compete with their former benefactors for resources.
Read more about this topic: Ecological Facilitation
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—Sigmund Freud (1856–1939)
“All cultural change reduces itself to a difference of categories. All revolutions, whether in the sciences or world history, occur merely because spirit has changed its categories in order to understand and examine what belongs to it, in order to possess and grasp itself in a truer, deeper, more intimate and unified manner.”
—Georg Wilhelm Friedrich Hegel (1770–1831)