Hutchinson's Ecological Niche

n-dimensional hypervolume — 2D niche overlap, competition, and coexistence

Species A (green)
38
42
20
18
Species B (blue)
55
50
22
16
Niche overlap (Schoener's D)
Hutchinson (1957) defined the fundamental niche as an n-dimensional hypervolume in environmental factor space where a species can persist. Where niches overlap, species compete. Competitive exclusion (Gause's law) predicts that two species cannot stably coexist on the same limiting resource — overlap must decrease via character displacement. Schoener's D = 1 − ½Σ|p_Ai − p_Bi| measures niche overlap on [0,1]. Modern extensions (Chesson 2000) use overlap to quantify stabilizing vs fitness differences.