Abstract
Although phylogenetic distance between native and exotic species has a
close link with their interactions, it is still unclear how
environmental stresses and species interactions influence the effect of
phylogenetic distance on biological invasion. Here we assessed the
effect of invader-native phylogenetic distance on the growth of the
invader (Symphyotrichum subulatum) under three levels of drought (no,
moderate or intensive drought). We found the effect of communities with
closely related natives on the invader shifted from negative (supporting
Darwin’s naturalization hypothesis) to positive (supporting the
pre-adaptation hypothesis.) with increasing drought intensity, which
could be largely explained by the shift of species interactions from
competition to facilitation by mutualism with arbuscular mycorrhizal
fungi. Therefore, our results provide a new angle to resolve Darwin’s
naturalization conundrum from the change of species interactions along a
stress gradient, and provide important clues for invasion management in
the changing environments.