Figures
Figure 1 Plant–orthoptera ecological networks for low- and high-elevation sites situated along three elevation transects. For each network, yellow bars represent species of orthoptera and green bars species of plant. To ease graph interpretation, species labels are grouped into genera for orthoptera and into families for plants, sorted according to the phylogeny. For species belonging to non-monophyletic genera (e.g. Chorthippus ), taxa are indicated with a number following the genus name. The reconstruction of plant and insect phylogenies is detailed in Appendix S1, section Methods. Bars with no label correspond to the taxa of the preceding labelled bar, reading from left to right. The width of the links represents interaction intensity.
Figure 2 Relationship between the mean summer temperature at each site along the elevation gradients and various plant–orthoptera network metrics: number of links per species (a), network generality (b), weighted nestedness (c), and network robustness (d). Expected metrics based on null models are represented in light gray. Regression lines result from linear mixed effects models, where solid lines indicate a significant relationship between the observed or random network metrics and the temperature. For empirical networks, the confidence interval and regression line of the temperature vs.metric relationship is shown. When the slope of the empirical relationship is outside the 2.5–97.5% quantile interval of the slopes obtained from random networks, the regression line and metric values are red, while they are dark grey when the observed slope is not outside the slope interval expected from null models.
Figure 3 Distribution of keystone species in the functional space of the plant traits between low- (a, <1050 m a.s.l.) and high-elevation (b, >2000 m) plant communities. Plant species are projected onto the first two axes of the principal components analysis (PCA) performed on plant functional traits, which explain 58.8% (PC1) and 15.6% (PC2) of the variance. The top 10 keystone species are colored by plant taxonomic group, while all other species are shown in black. The keystone score corresponds to the mean number of secondary extinctions caused by the removal of the plant species. It varies between 0.12 and 0.75 secondary extinctions across all networks but is summarized in the legend as three circle sizes (low, medium and high). Correlations between plant functional traits (C/N, LDMC, punch and SLA) and the two first axes of the PCA are given in the plot in the top right corner.
Figure 4 Matrix representation of the plant–orthoptera ecological networks for pairs of low- and high-elevation sites found along three elevation transects. Columns and rows correspond respectively to orthopteran and plant species. Interaction intensity is indicated by the color gradient with dark blue corresponding to maximal interaction strength and white to interaction absence.