Theory holds that sympatric large mammalian herbivores (LMH) must partition food resources to coexist, and LMH are traditionally categorized along a spectrum from grass-eating grazers to non-grass-eating browsers. Yet it has

never been clear how well LMH within these broad functional groups partition the enormous local plant species diversity. By sequencing plant DNA from LMH fecal (poop) samples, researchers analyzed the diets of an African LMH assemblage in Kenya. Consider the multivariate plot below (Fig. 4A from Kartzinel et al. 2015) showing how LMH species differ with respect to diet, based on the observed variation in plant species DNA found in each fecal sample. In NMDS plots, each point represents a multidimensional sample (in this case, diet composition of a given animal) and the relative distance between points is indicative of the degree of dissimilarity between two samples. Points that are far apart are less similar (i.e., more dissimilar) to each other than are points that are close together. A NMDS2 -1.0 -0.5 0.0 0.5 1.0 1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 NMDS1 Plains zebra Grevy's zebra Buffalo Cattle A Elephant A Impala Dik-Dik Fig. 4A. Niche partitioning within and among feeding guilds. Non-Metric Multidimensional Scaling (NMDS) ordination of Bray-Curtis dissimilarity values of diet samples from individuals representing all seven LMH species (pseudo F6,285 = 59.0, P ≤ 0.0001). Symbols distinguish "grazers" (circles), "mixed feeders" (triangles), and "browsers" (squares). What is/are the independent variable(s) in this analysis? species identity (e.g., zebra, buffalo, elephant, etc.) O feeding guild (functional group defined as species that eat similar things) both A and B O diet composition (as measured by plant DNA in animal fecal samples) O diet composition (as measured by field observations of feeding animals)