Chapter 54: Community Ecology Community = group of populations of different species living close enough to interact Interspecific interactions Can be positive (+), negative (-) or neutral (0) Includes: Competition (-/-) Predation (+/-) Herbivory (+/-) Symbiosis ? parasitism, mutualism, commensalism Facilitation (+/+ or 0/+) Interspecific competition: resources are in short supply Species interaction is -/- Competitive exclusion principle: Two species cannot coexist in a community if their niches are identical. The one with the slight reproductive advantage will eliminate the other Resource partitioning: differences in niches that enable similar species to coexist Ecological niche: the sum total of an organism?s use of abiotic/biotic resources in the environment