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.