Utility of observational datasets to predict genetic
differentiation
Biomass corrected reproductive traits, compared to vegetative traits,
showed a better match between observational trait-environment
relationships and response to source environmental gradients in the
greenhouse (Table 1). For vegetative traits, there were two cases of
predictable genetic differentiation out of eight. In both cases, field
data correctly predicted not the presence but the absence of genetic
differentiation. The low predictability in vegetative traits originated
in some cases from interacting (e.g., Fig. 4b) or opposing (Fig. 4d,e)
effects of source and exposure environments. In other cases, field
patterns did not match with those expected from the combined source and
exposure greenhouse effects (Fig. 4a). For biomass-corrected
reproductive traits, observational data predicted the presence and
direction of all seven source environment effects in the greenhouse.
However, when reproductive traits were analysed without biomass as a
covariate, observational data only predicted the presence and direction
of three out of seven source environment effects (Table S10).