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Biology LibreTexts

2.3.1: Biotic Interactions

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  • Biotic interactions refer to the relationships among organisms. They can be intraspecific (between members of the same species) or interspecific (between members of different species). When at least one of the interactants is harmed, the relationship is called an antagonism. Trophic interactions, in which one species consumes another, are antagonisms. Competition is another antagonism in which species at the same trophic level (that eat the same things) interact through using the same resources. Interactions in which at least one species benefits and neither is harmed are called facilitation, which can be categorized as commensalism or mutualism. 

    Vegetation surrounding water at Seal Beach National Wildlife Refuge

    A Light-Footed Clapper Rail standing in muddy water near cordgrass

    Figure \(\PageIndex{a}\): A variety of biotic interactions occur among the species at The Seal Beach National Wildlife Refuge (top). For example, the Light-Footed Clapper Rail (bottom) benefits from the cordgrass in which it nests. However, predators such as red foxes harm this endangered bird. The refuge manages this harmful interaction by installing fencing to exclude the red fox, which historically did not occur in the area. Top image and bottom image by US Fish & Wildlife Service (public domain).


    Modified by Melissa Ha from Community Ecology from Environmental Biology by Matthew R. Fisher (licensed under CC-BY)