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)