Evidence for niche theory in small mammals along an elevational gradient as revealed by isotopic signatures

Exploring and understanding mechanisms of species coexistence remains central to ecological theory. Our study tested predictions of niche theory by examining the isotopic niches of small mammal communities in the four forest types (oak, beech, spruce, timberline) along an elevational gradient in the Southern Carpathian Mountains of Romania. We analyzed δ¹³C and δ¹⁵N values from hair samples of seven rodent and insectivore species collected from oak, beech, spruce and timberline forests over three years. Using stable isotope analysis—Bayesian ellipses and convex hull metrics—we evaluated niche width, overlap and community-level structure.