Data from: Darwin’s naturalization conundrum reconciled by changes of species interactions

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 relationship between
phylogenetic distance and biological invasions. 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). Under no drought, interspecific
competition between close relatives was the
dominant process, and native communities more closely related to the
invader showed higher resistance to invasion, supporting Darwin’s
naturalization hypothesis. In contrast, under intensive drought,
facilitation between close relatives by
mutualism with arbuscular mycorrhizal fungi (AMF) became more
important, and the invader became more successful in
their more closely related native communities, supporting the
pre-adaptation hypothesis. The colonization rate of AMF
of the invader was higher in more closely related native
communities regardless
of the drought treatment, but
it was only positively related to invader biomass under intensive drought. Therefore, the shift of species interactions from competition to facilitation may be ascribed to the promotion of AMF to invasion occurring under intensive drought, which leads to the effect of closely related natives on the invader shifting from negative to positive. 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 when species interactions change in response to global climatic change.