Field surveys and network reconstruction
We identified 45 orthopteran species, including 29 and 16 species of the
Caelifera and Ensifera suborders, respectively, and we collected 403
feces samples. Vegetation surveys led to the identification of 496 plant
species, belonging to 265 genera and 63 families. The DNA barcoding
reference database compiled 5969 reference sequences covering the
taxonomic diversity of the vegetation surveys for 95.2% of the
families, 92.2% of the genera and 88.5% of the species, with 50% of
the missing species having their genus represented in the database. The
MiSeq v3 2x300 PE sequencing run provided 31 M reads, which decreased to
15.5 M after filtering, paired-end merging and trimming steps
(https://github.com/lh3/seqtk; Magoc & Salzberg 2011; Martin
2011), with an average sequencing depth of >36,500 reads,
and to 1774 OTUs after OTU calling (Edgar 2016). Following taxonomic
identification that used a stringent threshold of assignment of 0.95, we
discarded 105 OTUs that were not monophyletic and 176 OTUs with a
taxonomic assignment higher than the family level. After the merging of
OTUs belonging to the same taxon, the equal redistribution of read
counts to lower taxonomic ranks (Methods and Results sections in
Appendix S2) and the addition of species that had not been consumed, the
OTU table comprised 601 taxa, including 496 species, 99 genera and 6
families corresponding to taxa that were not identified to a lower
taxonomic level in the field. The total number of interactions recorded
was 10,615 out of 28,127 possible links. The reconstruction of
individual networks exemplified for low- and high-elevation sites of
three transects are illustrated in Fig. 1.