DOI: 10.5061/dryad.4f4qrfjdk
title: Mechanisms of dietary resource partitioning in large-herbivore assemblages: a plant-trait-based approach

description: Sympatric large mammalian herbivore species differ in diet composition,
 both by eating different parts of the same plant and by eating different
 plant species. Various theories proposed to explain these differences are
 not mutually exclusive, but are difficult to reconcile and confront with
 data. Moreover, whereas several of these ideas were originally developed
 with reference to within-plant partitioning (i.e., consumption of
 different tissues), they may analogously apply to partitioning of plant
 species; this possibility has received little attention. Plant functional
 traits provide a novel window into herbivore diets and a means of testing
 multiple hypotheses in a unified framework. We used DNA metabarcoding to
 characterize the diets of 14 sympatric large-herbivore species in an
 African savanna and analyzed diet composition in light of 27 functional
 traits that we measured locally for 204 plant species. Plant traits
 associated with the deep phylogenetic split between grasses and eudicots
 formed the primary axis of resource partitioning, affirming the generality
 and importance of the grazer-browser spectrum. A secondary axis comprised
 plant traits relevant to herbivore body size. Plant taxa in the diets of
 large-bodied species were lower on average in digestible energy and
 protein, taller on average (especially among grazers), and tended to be
 higher in tensile strength, zinc, stem-specific density, and potassium
 (and lower in sodium, stem dry matter content, and copper). These results
 are consistent with longstanding hypotheses linking body size with forage
 quality and plant height, yet they also suggest the existence of
 undiscovered links between herbivore body size and a set of rarely
 considered food-plant traits. We also tested the novel hypothesis that the
 leaf economic spectrum (LES), a major focus in plant ecology, is an axis
 of resource partitioning in large-herbivore assemblages; we found that the
 LES was a minor axis of individual variation within a few species, but had
 little effect on interspecific dietary differentiation. Synthesis. These
 results identify key plant traits that underpin the partitioning of
 food-plant species in large-herbivore communities and suggest that
 accounting for multiple plant traits (and tradeoffs among them) will
 enable a deeper understanding of herbivore-plant interaction networks.
description: See methods in Potter et al. Journal of Ecology.
description: This dataset contains plant trait data (two versions) and
 herbivore diet data (two versions), as well as keys to interpreting plant
 and herbivore taxa (three files). A README file is included.
 To generate the diet-weighted trait averages, matrix multiply the
 diet data by the plant trait data. For this to work, the columns of the
 left matrix (diet) must exactly match the rows of the right matrix
 (traits). Using the 'TOTU' versions of the diet and trait data
 accomplishes this. In R, the following code works: as.matrix(diet) %*%
 as.matrix(traits) .  Please consult the README file for
 important details.