DOI: 10.5061/dryad.kd51c5b52
title: Data from: The effect of community-wide phytochemical diversity on herbivory reverses from low to high elevation

description: 1. Theory predicts that a large fraction of phytochemical diversity – the
 richness of individual chemical compounds produced by plants – governs the
 complexity of interactions between plants and their herbivores. While the
 effect of specific classes of chemical compounds on plant resistance
 against herbivores has been largely documented, the effect of
 community-level variation in phytochemical diversity on plant-herbivore
 interactions has so far received minimal consideration. 2. We hypothesized
 that plant communities bearing on average higher levels of phytochemical
 diversity should sustain lower herbivory rates, overall. Yet, the
 magnitude of this effect could vary across different environmental
 conditions, potentially because of climate- mediated effects on
 phytochemical production and changes in herbivore community richness and
 composition. 3. To address these hypotheses, we used previous knowledge of
 species-level phytochemical make-up for more than 400 plant species of the
 Swiss Alps. Using common garden experiments, we estimated season-wide
 herbivore damage on low- (average 3500 unique molecules) and high-
 (average 4500 unique molecules) phytochemical diversity plant communities
 that were planted in the colline, mountain, and alpine vegetation sites
 along two elevation transects in the Alps. 4. We found that
 high-phytochemical diversity plant communities showed reduced levels of
 herbivore damage in the colline (low elevation) sites, but this pattern
 reversed in the alpine (high elevation) sites. Our results suggest that
 the outcome of phytochemical diversity on plant-herbivore interactions
 depends on the characteristics of the local herbivore communities,
 together with trade-offs between chemical defences and other plant traits
 (i.e. physical defences and plant palatability). 5. Synthesis –
 Phytochemical diversity is a key component of functional diversity,
 influencing community composition and dynamics. We show that the effect of
 phytochemical diversity on herbivory is environmental-dependent,
 generating ecological switches when moving from low to high elevation.
 Through upward movement of plants under climate change, phytochemical
 community structure will be likely modified, ultimately disrupting local
 community assembly processes.
description: Datasets included in the archive file are stored within the
 following subfolders: 
 "Field_and_plant_data.xslx" : this subfolder includes
 field data and species trait information for each experimental
 plant. The first worksheet
 ("Plant_data") includes plant level information (species
 identity, plant community and phytochemical diversity group), location
 (region in Swiss alps and elevation of planting), herbivory estimations at
 four time points and plant biomass at the end of the season.
 The second worksheet
 ("Species_traits") includes the species-level information of
 phytochemical richness measured in our experimental plants by using
 HPLC-DDA methods, HPLC-DIA values of phytochemical richness from Defossez
 et al. (2021), and mean traits values retrieved from Descombes et al.
 (2020) and Pitteloud et al. (2020). 
 "Metabolomic_raw_data.csv" corresponds to the
 molecular features matrix obtained from the experimentally-grown plants.
 Given are the spectra peaks heights for each molecular feature detected in
 each sample, as well as the sample information (species identity and
 location). Metabolomic data was adquired by ultra-high-performance liquid
 chromatography - high resolution tandem mass spectrometry using
 data-dependent analysis (DDA) and analyzed with MZMINE 2.53.