TY - JOUR TI - Variation in trophic niche sizes of terrestrial predators along an elevation gradient DO - https://doi.org/doi:10.7282/T3H70JV0 PY - 2017 AB - Environmental gradients and species traits can have important impacts on trophic interactions and communities. Changes in temperature and productivity can directly or indirectly affect the structure of food webs through their influence on the body mass and diversity of organisms. Additionally, functional traits such as hunting mode can select for wider or narrower range of prey diversity influencing consumer-resource interactions and the trophic niches of consumers.Here we used stable isotope analyses (δ13C and δ15N) to investigate the variation of trophic niche size of predatory spiders as a function of changes in biotic and abiotic factors, as well as determine the differences in trophic niche sizes among web-building spiders, along an elevation gradient in the Andes Mountains (Ecuador). We conducted spider-prey capture observations within each location to determine realized prey and performed arthropod sampling from the environment to estimate prey availability. We found significant differences in trophic niche size across sites, web architectures, and among populations through the elevation gradient. We found that the trophic niche sizes of the whole spider community and that of orb and sheet weaving spider were positively correlated with elevation. Additionally, orb and sheet weaving webs displayed similar trophic niche sizes at three out of four locations. Within a single orb-weaving spider species, Leucauge venusta displayed higher trophic niche sizes at the lower elevation sites and was correlated with changes in temperature, net primary productivity and prey diversity. This study shows that environmental changes in abiotic and biotic variables as well as functional traits such as foraging method can influence the trophic niche of generalist predators and the structure of food webs. KW - Biology KW - Food chains (Ecology) LA - eng ER -