Data from: The role of volatile plant secondary metabolites as pre-ingestive cues and potential toxins dictating diet selection by African elephants
Schmitt, Melissa H.
Shrader, Adrian M.
Published Aug 21, 2019 on Dryad.
Cite this dataset
Schmitt, Melissa H.; Shuttleworth, Adam; Shrader, Adrian M.; Ward, David (2019). Data from: The role of volatile plant secondary metabolites as pre-ingestive cues and potential toxins dictating diet selection by African elephants [Dataset]. Dryad. https://doi.org/10.5061/dryad.5rk1851
Understanding the factors driving diet selection represents one of the main thrusts of contemporary foraging ecology. Many studies have focussed on nutritional factors and anti-nutritional factors (such as tannins) that may describe diet selection of generalist mammalian herbivores, but these often do not explain the observed feeding patterns. Alternatively, generalist herbivores may be influenced by the presence, diversity, and/or concentration of toxins. Plant volatiles have been understudied, yet may play an important role in this context. We aimed to determine whether diet selection by African elephants is better correlated with the presence and concentration of toxic plant secondary metabolites (PSMs) than with nutritional or anti-nutritional factors. We also aimed to identify the specific aspects of the plant-odour profiles that were correlated with dietary selection, which could be used as a pre-ingestive cue for food selection. We found that elephant diet selection was not well described by crude protein, in vitro digestibility, tannin concentration, and total polyphenol concentration. Instead, the best predictors of elephant diet choice were the number and absolute (total) emissions of potentially toxic volatile PSMs, specifically monoterpenes. Elephants avoided plant species that emitted a wider diversity of volatile PSMs, had higher total emissions, and higher numbers and emissions of monoterpenes. This suggests that PSMs with a high propensity to become toxins, such as monoterpenes, are likely a better indicator for elephant diet avoidance than nutritional or anti-nutritional factors. Moreover, we demonstrated that elephants can differentiate between food items based on odour alone, specifically volatile monoterpenes, suggesting that these animals are relying on specific volatile cues emitted from plants to direct their foraging choices prior to ingesting selected plants.
Relative amounts (% based on peak areas) of volatile organic compounds identified from headspace samples collected from leaves of preferred and avoided trees. Unidentified compounds are presented with the molecular mass first (if known) indicated by a * followed by the base peak and remaining fragments in decreasing order of abundance. tr = compounds representing < 0.005 % of the total odour blend. Identification criteria: A = library match confirmed with published linear n-alkane retention index (Van Den Dool & Kratz 1963), B = library match only, C = library match confirmed with synthetic standard.