About: Priority effect

In ecology, a priority effect is an impact that a particular species can have on community development due to prior arrival at a site. There are two basic types: An inhibitory priority effect which occurs when a species that arrives first at a site negatively impacts a species that arrives later by reducing the availability of space or resources. A facilitative priority effect occurs when a species that arrives first at a site alters abiotic or biotic conditions in ways that positively impact a species arriving later. Priority effects are a central and pervasive element of ecological community development which have important implications for natural systems as well as ecological restoration efforts.