Abstract
The evolutionary imbalance hypothesis predicts that species from ecologically stable regions of high genetic potential and intense competition are more likely to be invasive, while regions with the opposite characteristics are more likely to be invasible. Relative phylogenetic diversity (PD) of species' indigenous ranges could indicate evolutionary imbalance and help identify high‐risk invaders and vulnerable communities. We tested this with three seed addition experiments where 166 species of varying origins were sown into disturbed and undisturbed grassland plots. Species with high relative indigenous‐PD had high colonisation and first‐year survival regardless of disturbance, whereas species with low relative indigenous‐PD only colonised disturbed communities and at a lower rate. Species' indigenous‐PD did not appear to affect second‐year survival. Although long‐term outcomes are unknown, evidence suggests that species with high relative indigenous‐PD pose a high invasion risk, even to intact communities. Regional PD could help indicate species invasiveness and community invasibility, informing biosecurity.