Effects of source and exposure environment in the
greenhouse
In the analyses of drivers of trait variation in the greenhouse, the
best models always included effects of at least one source environmental
driver and both light and water exposure treatments (see blue lines in
Fig. 3; Table S3; Fig. S2-S6), but results differed between vegetative
and reproductive traits. For vegetative traits (biomass, SLA and RSR),
light or water treatments showed the strongest effect sizes when
compared with source drivers (Fig. 4c,f,i). The effect of source drivers
on biomass and SLA frequently changed between positive and negative
directions depending on the treatment (see interactions in Fig. 3a,b;
Fig. 4a,b,e). For biomass, the effects of Aridity, Vegetation cover and
Mowing differed among treatments, although effect sizes were low and had
95% confidence intervals (CI) that mostly overlapped with zero (Fig.
3a). For SLA, all source drivers were selected in the best model except
for Mowing. SLA showed two contrasting effects between source and
exposure environments: 1) SLA was lower in the Dry treatment, but higher
in plants from the most arid populations (Fig. 4d); 2) SLA was higher in
the treatment with lowest light, but also higher in populations with
lowest source vegetation cover and thus highest light availability (this
took place in treatment L33; Fig. 4e). RSR increased
with source Aridity, although the effect was smaller than the effect of
the Dry treatment (Fig. 4g,i).
For reproductive traits (biomass-corrected probability of flowering and
fecundity), exposure treatments exerted equivalent or smaller effects
than source drivers (Fig. 4l,o) and the effects of source drivers were
consistent in direction across treatments (Fig. 3d,e, 4k,m). Probability
of flowering was negatively affected by source Vegetation cover and
positively affected by Mowing, and exposure treatments changed the
magnitude of these source effects but not their sign (Fig. 3d, 4k).
Fecundity was positively affected by source Aridity and Temperature, and
showed no interactions between source and exposure environments (Fig.
3e, 4m). When biomass was excluded as a covariate from the analyses, 1)
source effects decreased in magnitude and exposure effects generally
increased for probability of flowering, and 2) source effects were not
included in the best model of fecundity (Table S7).