Cytogeography of Naturalized Populations in Europe.

Autopolyploidization has driven the successful invasion of in East Asia. However, it was believed that only diploid invaded Europe, whereas polyploids never did. Here, molecular identification, ploidy level, and morphological traits of ten populations collected in Europe were compared with previously identified populations from other continents and populations. Furthermore, the ploidy-driven geographical differentiation pattern of in different continents was investigated. All ten European populations were identified as with five diploid and five hexaploid populations. Significant differences in morphological traits existed among diploids and polyploids (tetraploids and hexaploids), rather than between polyploids from different introduced ranges and between and polyploidy . The invasive hexaploids and diploids had few differences in latitudinal distributions in Europe, which was similar to the native range but different from a distinct climate-niche differentiation in Asia. This may be attributed to the bigger difference in climate between Asia and Europe and North America. The morphological and molecular evidences proved the invasion of polyploid in Europe and suggest that may be merged into a complex of species. Our study may be concluded that geographical and ecological niche differentiation of an invasive plant driven by ploidy depends on the degree of difference in the environmental factors between the introduced and native range, which provides new insight into the invasive mechanism.