"Mutualism: an interaction wherein both sides derive fitness benefits and the interaction occurs at the individual level (“+/+”)." "Facilitation: an interaction wherein at least one species derives a fitness benefit and the other side is not detrimentally affected." "Obligate: an interaction necessary for survival of one or both of the species involved. (Antonym: Facultative)" "Specific: an interaction in which a species has only a single partner or very small number of partners. (Antonym: General)" "Diffuse: an interaction involving many species or a network. (Antonym: Pairwise)"