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...