Polyploidization contributes to evolution of competitive ability: a long term common garden study on the invasive Solidago canadensis in China

Plant invasion initiates with the establishment of an alien species population that begins interacting with the existing community in the invaded habitat. Competitive ability may confer advantage to invasive species during establishment. Autopolyploidy has been shown to significantly contribute to successful invasion of China by Solidago canadensis that is native to North America. But how polyploidization improves competitive ability and determines the dominance of invasive species when competing with a plant community in the introduced range remains unclear. Here, we manipulated the initial plant composition of plowed land and subsequently allowed natural colonization by S. canadensis in a five-year common garden experiment. Diploid, tetraploid and hexaploid populations collected in North America (native range) and East Asia (introduced range) were separately planted and allowed to compete with associated weeds in individual plots. The diversity and compositional variation of the plant...