Phylogeography of apomictic and outcrossing individuals in invasive and native populations of Ardisia crenata (Primulaceae)

Phylogeography of invasive exotic plant species is crucial for identifying the source population from which a given invading population has originated. Ardisia crenata Sims, a shade tolerant shrub native to East Asia, is one of the most serious invasive exotic plants in Florida, North America. The objective of this study is to investigate the genetic differentiation and phylogeographical relationships among A. crenata native populations in Japan and invasive populations in Florida. We analyzed DNA from 188 individuals gathered from eight populations in Japan and four subpopulations in Florida using double‐digestion restriction‐associated DNA sequencing (ddRAD‐seq) and estimated a maximum likelihood phylogenetic tree among them. The results revealed four genetic clusters, with a striking dominance of genetically identical clonal individuals within the invading populations in Florida and four Honshu populations in Japan. These groups were genetically close to each other and to one cultivated individual sampled in Japan. In contrast, the individuals from Miyazaki, Yakushima, Kochi, and Iriomote in southwestern Japan were genetically distinct from Honshu and Florida individuals, showing high genetic diversity indicative of outcrossing. Given that A. crenata does not exhibit a vegetative clonal habit and all wild and cultivated plants regenerate from seeds, these results suggest that Honshu and Florida populations exclusively reproduced with seeds produced by apomixis.