From Encyclopedia Jr, free information reference for Kids
Neutralism describes the relationship (or lack thereof) between two species which do not interact with or affect each other. It is used in ecology to describe biological interactions when the population density of one species has absolutely no effect whatsoever on the other. Neutralism is extremely unlikely and impossible to prove. When dealing with the complex networks of interactions presented by ecosystems, one cannot assert positively that there is absolutely no interaction between two species. If two species do not interact directly, links can be found through other species and shared resources. Since true neutralism is rare or nonexistent, its usage is often extended to situations where interactions are merely insignificant or negligible.