In interspecies competition, two species use the same limited resource. Competition has a negative effect on both of the species (-/- interaction). A species' niche is basically its ecological role, which is defined by the set of conditions, resources, and interactions it needs (or can make use of).
: any of a series of chemical reactions in photosynthesis not requiring the presence of light and involving the reduction of carbon dioxide to form carbohydrate especially : calvin cycle.
